linux/drivers/acpi/pptt.c

814 lines
25 KiB

ACPI: PPTT: Leave the table mapped for the runtime usage Currently, everytime an information needs to be fetched from the PPTT, the table is mapped via acpi_get_table() and unmapped after the use via acpi_put_table() which is fine. However we do this at runtime especially when the CPU is hotplugged out and plugged in back since we re-populate the cache topology and other information. However, with the support to fetch LLC information from the PPTT in the cpuhotplug path which is executed in the atomic context, it is preferred to avoid mapping and unmapping of the PPTT for every single use as the acpi_get_table() might sleep waiting for a mutex. In order to avoid the same, the table is needs to just mapped once on the boot CPU and is never unmapped allowing it to be used at runtime with out the hassle of mapping and unmapping the table. Reported-by: Guenter Roeck <linux@roeck-us.net> Cc: Rafael J. Wysocki <rafael@kernel.org> Signed-off-by: Sudeep Holla <sudeep.holla@arm.com> -- Hi Rafael, Sorry to bother you again on this PPTT changes. Guenter reported an issue with lockdep enabled in -next that include my cacheinfo/arch_topology changes to utilise LLC from PPTT in the CPU hotplug path. Please ack the change once you are happy so that I can get it merged with other fixes via Greg's tree. Regards, Sudeep Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Link: https://lore.kernel.org/r/20220720-arch_topo_fixes-v3-2-43d696288e84@arm.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-07-20 13:55:39 +01:00
ACPI: PPTT: Fix to avoid sleep in the atomic context when PPTT is absent Commit 0c80f9e165f8 ("ACPI: PPTT: Leave the table mapped for the runtime usage") enabled to map PPTT once on the first invocation of acpi_get_pptt() and never unmapped the same allowing it to be used at runtime with out the hassle of mapping and unmapping the table. This was needed to fetch LLC information from the PPTT in the cpuhotplug path which is executed in the atomic context as the acpi_get_table() might sleep waiting for a mutex. However it missed to handle the case when there is no PPTT on the system which results in acpi_get_pptt() being called from all the secondary CPUs attempting to fetch the LLC information in the atomic context without knowing the absence of PPTT resulting in the splat like below: | BUG: sleeping function called from invalid context at kernel/locking/semaphore.c:164 | in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 0, name: swapper/1 | preempt_count: 1, expected: 0 | RCU nest depth: 0, expected: 0 | no locks held by swapper/1/0. | irq event stamp: 0 | hardirqs last enabled at (0): 0x0 | hardirqs last disabled at (0): copy_process+0x61c/0x1b40 | softirqs last enabled at (0): copy_process+0x61c/0x1b40 | softirqs last disabled at (0): 0x0 | CPU: 1 PID: 0 Comm: swapper/1 Not tainted 6.3.0-rc1 #1 | Call trace: | dump_backtrace+0xac/0x138 | show_stack+0x30/0x48 | dump_stack_lvl+0x60/0xb0 | dump_stack+0x18/0x28 | __might_resched+0x160/0x270 | __might_sleep+0x58/0xb0 | down_timeout+0x34/0x98 | acpi_os_wait_semaphore+0x7c/0xc0 | acpi_ut_acquire_mutex+0x58/0x108 | acpi_get_table+0x40/0xe8 | acpi_get_pptt+0x48/0xa0 | acpi_get_cache_info+0x38/0x140 | init_cache_level+0xf4/0x118 | detect_cache_attributes+0x2e4/0x640 | update_siblings_masks+0x3c/0x330 | store_cpu_topology+0x88/0xf0 | secondary_start_kernel+0xd0/0x168 | __secondary_switched+0xb8/0xc0 Update acpi_get_pptt() to consider the fact that PPTT is once checked and is not available on the system and return NULL avoiding any attempts to fetch PPTT and thereby avoiding any possible sleep waiting for a mutex in the atomic context. Fixes: 0c80f9e165f8 ("ACPI: PPTT: Leave the table mapped for the runtime usage") Reported-by: Aishwarya TCV <aishwarya.tcv@arm.com> Signed-off-by: Sudeep Holla <sudeep.holla@arm.com> Tested-by: Pierre Gondois <pierre.gondois@arm.com> Cc: 6.0+ <stable@vger.kernel.org> # 6.0+ Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2023-03-08 11:26:32 +00:00
ACPI: PPTT: Leave the table mapped for the runtime usage Currently, everytime an information needs to be fetched from the PPTT, the table is mapped via acpi_get_table() and unmapped after the use via acpi_put_table() which is fine. However we do this at runtime especially when the CPU is hotplugged out and plugged in back since we re-populate the cache topology and other information. However, with the support to fetch LLC information from the PPTT in the cpuhotplug path which is executed in the atomic context, it is preferred to avoid mapping and unmapping of the PPTT for every single use as the acpi_get_table() might sleep waiting for a mutex. In order to avoid the same, the table is needs to just mapped once on the boot CPU and is never unmapped allowing it to be used at runtime with out the hassle of mapping and unmapping the table. Reported-by: Guenter Roeck <linux@roeck-us.net> Cc: Rafael J. Wysocki <rafael@kernel.org> Signed-off-by: Sudeep Holla <sudeep.holla@arm.com> -- Hi Rafael, Sorry to bother you again on this PPTT changes. Guenter reported an issue with lockdep enabled in -next that include my cacheinfo/arch_topology changes to utilise LLC from PPTT in the CPU hotplug path. Please ack the change once you are happy so that I can get it merged with other fixes via Greg's tree. Regards, Sudeep Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Link: https://lore.kernel.org/r/20220720-arch_topo_fixes-v3-2-43d696288e84@arm.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-07-20 13:55:39 +01:00
ACPI: PPTT: Fix to avoid sleep in the atomic context when PPTT is absent Commit 0c80f9e165f8 ("ACPI: PPTT: Leave the table mapped for the runtime usage") enabled to map PPTT once on the first invocation of acpi_get_pptt() and never unmapped the same allowing it to be used at runtime with out the hassle of mapping and unmapping the table. This was needed to fetch LLC information from the PPTT in the cpuhotplug path which is executed in the atomic context as the acpi_get_table() might sleep waiting for a mutex. However it missed to handle the case when there is no PPTT on the system which results in acpi_get_pptt() being called from all the secondary CPUs attempting to fetch the LLC information in the atomic context without knowing the absence of PPTT resulting in the splat like below: | BUG: sleeping function called from invalid context at kernel/locking/semaphore.c:164 | in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 0, name: swapper/1 | preempt_count: 1, expected: 0 | RCU nest depth: 0, expected: 0 | no locks held by swapper/1/0. | irq event stamp: 0 | hardirqs last enabled at (0): 0x0 | hardirqs last disabled at (0): copy_process+0x61c/0x1b40 | softirqs last enabled at (0): copy_process+0x61c/0x1b40 | softirqs last disabled at (0): 0x0 | CPU: 1 PID: 0 Comm: swapper/1 Not tainted 6.3.0-rc1 #1 | Call trace: | dump_backtrace+0xac/0x138 | show_stack+0x30/0x48 | dump_stack_lvl+0x60/0xb0 | dump_stack+0x18/0x28 | __might_resched+0x160/0x270 | __might_sleep+0x58/0xb0 | down_timeout+0x34/0x98 | acpi_os_wait_semaphore+0x7c/0xc0 | acpi_ut_acquire_mutex+0x58/0x108 | acpi_get_table+0x40/0xe8 | acpi_get_pptt+0x48/0xa0 | acpi_get_cache_info+0x38/0x140 | init_cache_level+0xf4/0x118 | detect_cache_attributes+0x2e4/0x640 | update_siblings_masks+0x3c/0x330 | store_cpu_topology+0x88/0xf0 | secondary_start_kernel+0xd0/0x168 | __secondary_switched+0xb8/0xc0 Update acpi_get_pptt() to consider the fact that PPTT is once checked and is not available on the system and return NULL avoiding any attempts to fetch PPTT and thereby avoiding any possible sleep waiting for a mutex in the atomic context. Fixes: 0c80f9e165f8 ("ACPI: PPTT: Leave the table mapped for the runtime usage") Reported-by: Aishwarya TCV <aishwarya.tcv@arm.com> Signed-off-by: Sudeep Holla <sudeep.holla@arm.com> Tested-by: Pierre Gondois <pierre.gondois@arm.com> Cc: 6.0+ <stable@vger.kernel.org> # 6.0+ Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2023-03-08 11:26:32 +00:00
ACPI: PPTT: Leave the table mapped for the runtime usage Currently, everytime an information needs to be fetched from the PPTT, the table is mapped via acpi_get_table() and unmapped after the use via acpi_put_table() which is fine. However we do this at runtime especially when the CPU is hotplugged out and plugged in back since we re-populate the cache topology and other information. However, with the support to fetch LLC information from the PPTT in the cpuhotplug path which is executed in the atomic context, it is preferred to avoid mapping and unmapping of the PPTT for every single use as the acpi_get_table() might sleep waiting for a mutex. In order to avoid the same, the table is needs to just mapped once on the boot CPU and is never unmapped allowing it to be used at runtime with out the hassle of mapping and unmapping the table. Reported-by: Guenter Roeck <linux@roeck-us.net> Cc: Rafael J. Wysocki <rafael@kernel.org> Signed-off-by: Sudeep Holla <sudeep.holla@arm.com> -- Hi Rafael, Sorry to bother you again on this PPTT changes. Guenter reported an issue with lockdep enabled in -next that include my cacheinfo/arch_topology changes to utilise LLC from PPTT in the CPU hotplug path. Please ack the change once you are happy so that I can get it merged with other fixes via Greg's tree. Regards, Sudeep Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Link: https://lore.kernel.org/r/20220720-arch_topo_fixes-v3-2-43d696288e84@arm.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-07-20 13:55:39 +01:00
ACPI: PPTT: Fix to avoid sleep in the atomic context when PPTT is absent Commit 0c80f9e165f8 ("ACPI: PPTT: Leave the table mapped for the runtime usage") enabled to map PPTT once on the first invocation of acpi_get_pptt() and never unmapped the same allowing it to be used at runtime with out the hassle of mapping and unmapping the table. This was needed to fetch LLC information from the PPTT in the cpuhotplug path which is executed in the atomic context as the acpi_get_table() might sleep waiting for a mutex. However it missed to handle the case when there is no PPTT on the system which results in acpi_get_pptt() being called from all the secondary CPUs attempting to fetch the LLC information in the atomic context without knowing the absence of PPTT resulting in the splat like below: | BUG: sleeping function called from invalid context at kernel/locking/semaphore.c:164 | in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 0, name: swapper/1 | preempt_count: 1, expected: 0 | RCU nest depth: 0, expected: 0 | no locks held by swapper/1/0. | irq event stamp: 0 | hardirqs last enabled at (0): 0x0 | hardirqs last disabled at (0): copy_process+0x61c/0x1b40 | softirqs last enabled at (0): copy_process+0x61c/0x1b40 | softirqs last disabled at (0): 0x0 | CPU: 1 PID: 0 Comm: swapper/1 Not tainted 6.3.0-rc1 #1 | Call trace: | dump_backtrace+0xac/0x138 | show_stack+0x30/0x48 | dump_stack_lvl+0x60/0xb0 | dump_stack+0x18/0x28 | __might_resched+0x160/0x270 | __might_sleep+0x58/0xb0 | down_timeout+0x34/0x98 | acpi_os_wait_semaphore+0x7c/0xc0 | acpi_ut_acquire_mutex+0x58/0x108 | acpi_get_table+0x40/0xe8 | acpi_get_pptt+0x48/0xa0 | acpi_get_cache_info+0x38/0x140 | init_cache_level+0xf4/0x118 | detect_cache_attributes+0x2e4/0x640 | update_siblings_masks+0x3c/0x330 | store_cpu_topology+0x88/0xf0 | secondary_start_kernel+0xd0/0x168 | __secondary_switched+0xb8/0xc0 Update acpi_get_pptt() to consider the fact that PPTT is once checked and is not available on the system and return NULL avoiding any attempts to fetch PPTT and thereby avoiding any possible sleep waiting for a mutex in the atomic context. Fixes: 0c80f9e165f8 ("ACPI: PPTT: Leave the table mapped for the runtime usage") Reported-by: Aishwarya TCV <aishwarya.tcv@arm.com> Signed-off-by: Sudeep Holla <sudeep.holla@arm.com> Tested-by: Pierre Gondois <pierre.gondois@arm.com> Cc: 6.0+ <stable@vger.kernel.org> # 6.0+ Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2023-03-08 11:26:32 +00:00
ACPI: PPTT: Leave the table mapped for the runtime usage Currently, everytime an information needs to be fetched from the PPTT, the table is mapped via acpi_get_table() and unmapped after the use via acpi_put_table() which is fine. However we do this at runtime especially when the CPU is hotplugged out and plugged in back since we re-populate the cache topology and other information. However, with the support to fetch LLC information from the PPTT in the cpuhotplug path which is executed in the atomic context, it is preferred to avoid mapping and unmapping of the PPTT for every single use as the acpi_get_table() might sleep waiting for a mutex. In order to avoid the same, the table is needs to just mapped once on the boot CPU and is never unmapped allowing it to be used at runtime with out the hassle of mapping and unmapping the table. Reported-by: Guenter Roeck <linux@roeck-us.net> Cc: Rafael J. Wysocki <rafael@kernel.org> Signed-off-by: Sudeep Holla <sudeep.holla@arm.com> -- Hi Rafael, Sorry to bother you again on this PPTT changes. Guenter reported an issue with lockdep enabled in -next that include my cacheinfo/arch_topology changes to utilise LLC from PPTT in the CPU hotplug path. Please ack the change once you are happy so that I can get it merged with other fixes via Greg's tree. Regards, Sudeep Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Link: https://lore.kernel.org/r/20220720-arch_topo_fixes-v3-2-43d696288e84@arm.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-07-20 13:55:39 +01:00
ACPI: PPTT: Leave the table mapped for the runtime usage Currently, everytime an information needs to be fetched from the PPTT, the table is mapped via acpi_get_table() and unmapped after the use via acpi_put_table() which is fine. However we do this at runtime especially when the CPU is hotplugged out and plugged in back since we re-populate the cache topology and other information. However, with the support to fetch LLC information from the PPTT in the cpuhotplug path which is executed in the atomic context, it is preferred to avoid mapping and unmapping of the PPTT for every single use as the acpi_get_table() might sleep waiting for a mutex. In order to avoid the same, the table is needs to just mapped once on the boot CPU and is never unmapped allowing it to be used at runtime with out the hassle of mapping and unmapping the table. Reported-by: Guenter Roeck <linux@roeck-us.net> Cc: Rafael J. Wysocki <rafael@kernel.org> Signed-off-by: Sudeep Holla <sudeep.holla@arm.com> -- Hi Rafael, Sorry to bother you again on this PPTT changes. Guenter reported an issue with lockdep enabled in -next that include my cacheinfo/arch_topology changes to utilise LLC from PPTT in the CPU hotplug path. Please ack the change once you are happy so that I can get it merged with other fixes via Greg's tree. Regards, Sudeep Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Link: https://lore.kernel.org/r/20220720-arch_topo_fixes-v3-2-43d696288e84@arm.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-07-20 13:55:39 +01:00
ACPI: PPTT: Leave the table mapped for the runtime usage Currently, everytime an information needs to be fetched from the PPTT, the table is mapped via acpi_get_table() and unmapped after the use via acpi_put_table() which is fine. However we do this at runtime especially when the CPU is hotplugged out and plugged in back since we re-populate the cache topology and other information. However, with the support to fetch LLC information from the PPTT in the cpuhotplug path which is executed in the atomic context, it is preferred to avoid mapping and unmapping of the PPTT for every single use as the acpi_get_table() might sleep waiting for a mutex. In order to avoid the same, the table is needs to just mapped once on the boot CPU and is never unmapped allowing it to be used at runtime with out the hassle of mapping and unmapping the table. Reported-by: Guenter Roeck <linux@roeck-us.net> Cc: Rafael J. Wysocki <rafael@kernel.org> Signed-off-by: Sudeep Holla <sudeep.holla@arm.com> -- Hi Rafael, Sorry to bother you again on this PPTT changes. Guenter reported an issue with lockdep enabled in -next that include my cacheinfo/arch_topology changes to utilise LLC from PPTT in the CPU hotplug path. Please ack the change once you are happy so that I can get it merged with other fixes via Greg's tree. Regards, Sudeep Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Link: https://lore.kernel.org/r/20220720-arch_topo_fixes-v3-2-43d696288e84@arm.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-07-20 13:55:39 +01:00
ACPI: PPTT: Leave the table mapped for the runtime usage Currently, everytime an information needs to be fetched from the PPTT, the table is mapped via acpi_get_table() and unmapped after the use via acpi_put_table() which is fine. However we do this at runtime especially when the CPU is hotplugged out and plugged in back since we re-populate the cache topology and other information. However, with the support to fetch LLC information from the PPTT in the cpuhotplug path which is executed in the atomic context, it is preferred to avoid mapping and unmapping of the PPTT for every single use as the acpi_get_table() might sleep waiting for a mutex. In order to avoid the same, the table is needs to just mapped once on the boot CPU and is never unmapped allowing it to be used at runtime with out the hassle of mapping and unmapping the table. Reported-by: Guenter Roeck <linux@roeck-us.net> Cc: Rafael J. Wysocki <rafael@kernel.org> Signed-off-by: Sudeep Holla <sudeep.holla@arm.com> -- Hi Rafael, Sorry to bother you again on this PPTT changes. Guenter reported an issue with lockdep enabled in -next that include my cacheinfo/arch_topology changes to utilise LLC from PPTT in the CPU hotplug path. Please ack the change once you are happy so that I can get it merged with other fixes via Greg's tree. Regards, Sudeep Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Link: https://lore.kernel.org/r/20220720-arch_topo_fixes-v3-2-43d696288e84@arm.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-07-20 13:55:39 +01:00
ACPI: PPTT: Leave the table mapped for the runtime usage Currently, everytime an information needs to be fetched from the PPTT, the table is mapped via acpi_get_table() and unmapped after the use via acpi_put_table() which is fine. However we do this at runtime especially when the CPU is hotplugged out and plugged in back since we re-populate the cache topology and other information. However, with the support to fetch LLC information from the PPTT in the cpuhotplug path which is executed in the atomic context, it is preferred to avoid mapping and unmapping of the PPTT for every single use as the acpi_get_table() might sleep waiting for a mutex. In order to avoid the same, the table is needs to just mapped once on the boot CPU and is never unmapped allowing it to be used at runtime with out the hassle of mapping and unmapping the table. Reported-by: Guenter Roeck <linux@roeck-us.net> Cc: Rafael J. Wysocki <rafael@kernel.org> Signed-off-by: Sudeep Holla <sudeep.holla@arm.com> -- Hi Rafael, Sorry to bother you again on this PPTT changes. Guenter reported an issue with lockdep enabled in -next that include my cacheinfo/arch_topology changes to utilise LLC from PPTT in the CPU hotplug path. Please ack the change once you are happy so that I can get it merged with other fixes via Greg's tree. Regards, Sudeep Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Link: https://lore.kernel.org/r/20220720-arch_topo_fixes-v3-2-43d696288e84@arm.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-07-20 13:55:39 +01:00
ACPI: PPTT: Leave the table mapped for the runtime usage Currently, everytime an information needs to be fetched from the PPTT, the table is mapped via acpi_get_table() and unmapped after the use via acpi_put_table() which is fine. However we do this at runtime especially when the CPU is hotplugged out and plugged in back since we re-populate the cache topology and other information. However, with the support to fetch LLC information from the PPTT in the cpuhotplug path which is executed in the atomic context, it is preferred to avoid mapping and unmapping of the PPTT for every single use as the acpi_get_table() might sleep waiting for a mutex. In order to avoid the same, the table is needs to just mapped once on the boot CPU and is never unmapped allowing it to be used at runtime with out the hassle of mapping and unmapping the table. Reported-by: Guenter Roeck <linux@roeck-us.net> Cc: Rafael J. Wysocki <rafael@kernel.org> Signed-off-by: Sudeep Holla <sudeep.holla@arm.com> -- Hi Rafael, Sorry to bother you again on this PPTT changes. Guenter reported an issue with lockdep enabled in -next that include my cacheinfo/arch_topology changes to utilise LLC from PPTT in the CPU hotplug path. Please ack the change once you are happy so that I can get it merged with other fixes via Greg's tree. Regards, Sudeep Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Link: https://lore.kernel.org/r/20220720-arch_topo_fixes-v3-2-43d696288e84@arm.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-07-20 13:55:39 +01:00
ACPI: PPTT: Leave the table mapped for the runtime usage Currently, everytime an information needs to be fetched from the PPTT, the table is mapped via acpi_get_table() and unmapped after the use via acpi_put_table() which is fine. However we do this at runtime especially when the CPU is hotplugged out and plugged in back since we re-populate the cache topology and other information. However, with the support to fetch LLC information from the PPTT in the cpuhotplug path which is executed in the atomic context, it is preferred to avoid mapping and unmapping of the PPTT for every single use as the acpi_get_table() might sleep waiting for a mutex. In order to avoid the same, the table is needs to just mapped once on the boot CPU and is never unmapped allowing it to be used at runtime with out the hassle of mapping and unmapping the table. Reported-by: Guenter Roeck <linux@roeck-us.net> Cc: Rafael J. Wysocki <rafael@kernel.org> Signed-off-by: Sudeep Holla <sudeep.holla@arm.com> -- Hi Rafael, Sorry to bother you again on this PPTT changes. Guenter reported an issue with lockdep enabled in -next that include my cacheinfo/arch_topology changes to utilise LLC from PPTT in the CPU hotplug path. Please ack the change once you are happy so that I can get it merged with other fixes via Greg's tree. Regards, Sudeep Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Link: https://lore.kernel.org/r/20220720-arch_topo_fixes-v3-2-43d696288e84@arm.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-07-20 13:55:39 +01:00
ACPI: PPTT: Leave the table mapped for the runtime usage Currently, everytime an information needs to be fetched from the PPTT, the table is mapped via acpi_get_table() and unmapped after the use via acpi_put_table() which is fine. However we do this at runtime especially when the CPU is hotplugged out and plugged in back since we re-populate the cache topology and other information. However, with the support to fetch LLC information from the PPTT in the cpuhotplug path which is executed in the atomic context, it is preferred to avoid mapping and unmapping of the PPTT for every single use as the acpi_get_table() might sleep waiting for a mutex. In order to avoid the same, the table is needs to just mapped once on the boot CPU and is never unmapped allowing it to be used at runtime with out the hassle of mapping and unmapping the table. Reported-by: Guenter Roeck <linux@roeck-us.net> Cc: Rafael J. Wysocki <rafael@kernel.org> Signed-off-by: Sudeep Holla <sudeep.holla@arm.com> -- Hi Rafael, Sorry to bother you again on this PPTT changes. Guenter reported an issue with lockdep enabled in -next that include my cacheinfo/arch_topology changes to utilise LLC from PPTT in the CPU hotplug path. Please ack the change once you are happy so that I can get it merged with other fixes via Greg's tree. Regards, Sudeep Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Link: https://lore.kernel.org/r/20220720-arch_topo_fixes-v3-2-43d696288e84@arm.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-07-20 13:55:39 +01:00
topology: Represent clusters of CPUs within a die Both ACPI and DT provide the ability to describe additional layers of topology between that of individual cores and higher level constructs such as the level at which the last level cache is shared. In ACPI this can be represented in PPTT as a Processor Hierarchy Node Structure [1] that is the parent of the CPU cores and in turn has a parent Processor Hierarchy Nodes Structure representing a higher level of topology. For example Kunpeng 920 has 6 or 8 clusters in each NUMA node, and each cluster has 4 cpus. All clusters share L3 cache data, but each cluster has local L3 tag. On the other hand, each clusters will share some internal system bus. +-----------------------------------+ +---------+ | +------+ +------+ +--------------------------+ | | | CPU0 | | cpu1 | | +-----------+ | | | +------+ +------+ | | | | | | +----+ L3 | | | | +------+ +------+ cluster | | tag | | | | | CPU2 | | CPU3 | | | | | | | +------+ +------+ | +-----------+ | | | | | | +-----------------------------------+ | | +-----------------------------------+ | | | +------+ +------+ +--------------------------+ | | | | | | | +-----------+ | | | +------+ +------+ | | | | | | | | L3 | | | | +------+ +------+ +----+ tag | | | | | | | | | | | | | | +------+ +------+ | +-----------+ | | | | | | +-----------------------------------+ | L3 | | data | +-----------------------------------+ | | | +------+ +------+ | +-----------+ | | | | | | | | | | | | | +------+ +------+ +----+ L3 | | | | | | tag | | | | +------+ +------+ | | | | | | | | | | | +-----------+ | | | +------+ +------+ +--------------------------+ | +-----------------------------------| | | +-----------------------------------| | | | +------+ +------+ +--------------------------+ | | | | | | | +-----------+ | | | +------+ +------+ | | | | | | +----+ L3 | | | | +------+ +------+ | | tag | | | | | | | | | | | | | | +------+ +------+ | +-----------+ | | | | | | +-----------------------------------+ | | +-----------------------------------+ | | | +------+ +------+ +--------------------------+ | | | | | | | +-----------+ | | | +------+ +------+ | | | | | | | | L3 | | | | +------+ +------+ +---+ tag | | | | | | | | | | | | | | +------+ +------+ | +-----------+ | | | | | | +-----------------------------------+ | | +-----------------------------------+ | | | +------+ +------+ +--------------------------+ | | | | | | | +-----------+ | | | +------+ +------+ | | | | | | | | L3 | | | | +------+ +------+ +--+ tag | | | | | | | | | | | | | | +------+ +------+ | +-----------+ | | | | +---------+ +-----------------------------------+ That means spreading tasks among clusters will bring more bandwidth while packing tasks within one cluster will lead to smaller cache synchronization latency. So both kernel and userspace will have a chance to leverage this topology to deploy tasks accordingly to achieve either smaller cache latency within one cluster or an even distribution of load among clusters for higher throughput. This patch exposes cluster topology to both kernel and userspace. Libraried like hwloc will know cluster by cluster_cpus and related sysfs attributes. PoC of HWLOC support at [2]. Note this patch only handle the ACPI case. Special consideration is needed for SMT processors, where it is necessary to move 2 levels up the hierarchy from the leaf nodes (thus skipping the processor core level). Note that arm64 / ACPI does not provide any means of identifying a die level in the topology but that may be unrelate to the cluster level. [1] ACPI Specification 6.3 - section 5.2.29.1 processor hierarchy node structure (Type 0) [2] https://github.com/hisilicon/hwloc/tree/linux-cluster Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> Signed-off-by: Tian Tao <tiantao6@hisilicon.com> Signed-off-by: Barry Song <song.bao.hua@hisilicon.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20210924085104.44806-2-21cnbao@gmail.com
2021-09-24 20:51:02 +12:00
ACPI: PPTT: Leave the table mapped for the runtime usage Currently, everytime an information needs to be fetched from the PPTT, the table is mapped via acpi_get_table() and unmapped after the use via acpi_put_table() which is fine. However we do this at runtime especially when the CPU is hotplugged out and plugged in back since we re-populate the cache topology and other information. However, with the support to fetch LLC information from the PPTT in the cpuhotplug path which is executed in the atomic context, it is preferred to avoid mapping and unmapping of the PPTT for every single use as the acpi_get_table() might sleep waiting for a mutex. In order to avoid the same, the table is needs to just mapped once on the boot CPU and is never unmapped allowing it to be used at runtime with out the hassle of mapping and unmapping the table. Reported-by: Guenter Roeck <linux@roeck-us.net> Cc: Rafael J. Wysocki <rafael@kernel.org> Signed-off-by: Sudeep Holla <sudeep.holla@arm.com> -- Hi Rafael, Sorry to bother you again on this PPTT changes. Guenter reported an issue with lockdep enabled in -next that include my cacheinfo/arch_topology changes to utilise LLC from PPTT in the CPU hotplug path. Please ack the change once you are happy so that I can get it merged with other fixes via Greg's tree. Regards, Sudeep Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Link: https://lore.kernel.org/r/20220720-arch_topo_fixes-v3-2-43d696288e84@arm.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-07-20 13:55:39 +01:00
topology: Represent clusters of CPUs within a die Both ACPI and DT provide the ability to describe additional layers of topology between that of individual cores and higher level constructs such as the level at which the last level cache is shared. In ACPI this can be represented in PPTT as a Processor Hierarchy Node Structure [1] that is the parent of the CPU cores and in turn has a parent Processor Hierarchy Nodes Structure representing a higher level of topology. For example Kunpeng 920 has 6 or 8 clusters in each NUMA node, and each cluster has 4 cpus. All clusters share L3 cache data, but each cluster has local L3 tag. On the other hand, each clusters will share some internal system bus. +-----------------------------------+ +---------+ | +------+ +------+ +--------------------------+ | | | CPU0 | | cpu1 | | +-----------+ | | | +------+ +------+ | | | | | | +----+ L3 | | | | +------+ +------+ cluster | | tag | | | | | CPU2 | | CPU3 | | | | | | | +------+ +------+ | +-----------+ | | | | | | +-----------------------------------+ | | +-----------------------------------+ | | | +------+ +------+ +--------------------------+ | | | | | | | +-----------+ | | | +------+ +------+ | | | | | | | | L3 | | | | +------+ +------+ +----+ tag | | | | | | | | | | | | | | +------+ +------+ | +-----------+ | | | | | | +-----------------------------------+ | L3 | | data | +-----------------------------------+ | | | +------+ +------+ | +-----------+ | | | | | | | | | | | | | +------+ +------+ +----+ L3 | | | | | | tag | | | | +------+ +------+ | | | | | | | | | | | +-----------+ | | | +------+ +------+ +--------------------------+ | +-----------------------------------| | | +-----------------------------------| | | | +------+ +------+ +--------------------------+ | | | | | | | +-----------+ | | | +------+ +------+ | | | | | | +----+ L3 | | | | +------+ +------+ | | tag | | | | | | | | | | | | | | +------+ +------+ | +-----------+ | | | | | | +-----------------------------------+ | | +-----------------------------------+ | | | +------+ +------+ +--------------------------+ | | | | | | | +-----------+ | | | +------+ +------+ | | | | | | | | L3 | | | | +------+ +------+ +---+ tag | | | | | | | | | | | | | | +------+ +------+ | +-----------+ | | | | | | +-----------------------------------+ | | +-----------------------------------+ | | | +------+ +------+ +--------------------------+ | | | | | | | +-----------+ | | | +------+ +------+ | | | | | | | | L3 | | | | +------+ +------+ +--+ tag | | | | | | | | | | | | | | +------+ +------+ | +-----------+ | | | | +---------+ +-----------------------------------+ That means spreading tasks among clusters will bring more bandwidth while packing tasks within one cluster will lead to smaller cache synchronization latency. So both kernel and userspace will have a chance to leverage this topology to deploy tasks accordingly to achieve either smaller cache latency within one cluster or an even distribution of load among clusters for higher throughput. This patch exposes cluster topology to both kernel and userspace. Libraried like hwloc will know cluster by cluster_cpus and related sysfs attributes. PoC of HWLOC support at [2]. Note this patch only handle the ACPI case. Special consideration is needed for SMT processors, where it is necessary to move 2 levels up the hierarchy from the leaf nodes (thus skipping the processor core level). Note that arm64 / ACPI does not provide any means of identifying a die level in the topology but that may be unrelate to the cluster level. [1] ACPI Specification 6.3 - section 5.2.29.1 processor hierarchy node structure (Type 0) [2] https://github.com/hisilicon/hwloc/tree/linux-cluster Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> Signed-off-by: Tian Tao <tiantao6@hisilicon.com> Signed-off-by: Barry Song <song.bao.hua@hisilicon.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20210924085104.44806-2-21cnbao@gmail.com
2021-09-24 20:51:02 +12:00
ACPI: PPTT: Leave the table mapped for the runtime usage Currently, everytime an information needs to be fetched from the PPTT, the table is mapped via acpi_get_table() and unmapped after the use via acpi_put_table() which is fine. However we do this at runtime especially when the CPU is hotplugged out and plugged in back since we re-populate the cache topology and other information. However, with the support to fetch LLC information from the PPTT in the cpuhotplug path which is executed in the atomic context, it is preferred to avoid mapping and unmapping of the PPTT for every single use as the acpi_get_table() might sleep waiting for a mutex. In order to avoid the same, the table is needs to just mapped once on the boot CPU and is never unmapped allowing it to be used at runtime with out the hassle of mapping and unmapping the table. Reported-by: Guenter Roeck <linux@roeck-us.net> Cc: Rafael J. Wysocki <rafael@kernel.org> Signed-off-by: Sudeep Holla <sudeep.holla@arm.com> -- Hi Rafael, Sorry to bother you again on this PPTT changes. Guenter reported an issue with lockdep enabled in -next that include my cacheinfo/arch_topology changes to utilise LLC from PPTT in the CPU hotplug path. Please ack the change once you are happy so that I can get it merged with other fixes via Greg's tree. Regards, Sudeep Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Link: https://lore.kernel.org/r/20220720-arch_topo_fixes-v3-2-43d696288e84@arm.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-07-20 13:55:39 +01:00
topology: Represent clusters of CPUs within a die Both ACPI and DT provide the ability to describe additional layers of topology between that of individual cores and higher level constructs such as the level at which the last level cache is shared. In ACPI this can be represented in PPTT as a Processor Hierarchy Node Structure [1] that is the parent of the CPU cores and in turn has a parent Processor Hierarchy Nodes Structure representing a higher level of topology. For example Kunpeng 920 has 6 or 8 clusters in each NUMA node, and each cluster has 4 cpus. All clusters share L3 cache data, but each cluster has local L3 tag. On the other hand, each clusters will share some internal system bus. +-----------------------------------+ +---------+ | +------+ +------+ +--------------------------+ | | | CPU0 | | cpu1 | | +-----------+ | | | +------+ +------+ | | | | | | +----+ L3 | | | | +------+ +------+ cluster | | tag | | | | | CPU2 | | CPU3 | | | | | | | +------+ +------+ | +-----------+ | | | | | | +-----------------------------------+ | | +-----------------------------------+ | | | +------+ +------+ +--------------------------+ | | | | | | | +-----------+ | | | +------+ +------+ | | | | | | | | L3 | | | | +------+ +------+ +----+ tag | | | | | | | | | | | | | | +------+ +------+ | +-----------+ | | | | | | +-----------------------------------+ | L3 | | data | +-----------------------------------+ | | | +------+ +------+ | +-----------+ | | | | | | | | | | | | | +------+ +------+ +----+ L3 | | | | | | tag | | | | +------+ +------+ | | | | | | | | | | | +-----------+ | | | +------+ +------+ +--------------------------+ | +-----------------------------------| | | +-----------------------------------| | | | +------+ +------+ +--------------------------+ | | | | | | | +-----------+ | | | +------+ +------+ | | | | | | +----+ L3 | | | | +------+ +------+ | | tag | | | | | | | | | | | | | | +------+ +------+ | +-----------+ | | | | | | +-----------------------------------+ | | +-----------------------------------+ | | | +------+ +------+ +--------------------------+ | | | | | | | +-----------+ | | | +------+ +------+ | | | | | | | | L3 | | | | +------+ +------+ +---+ tag | | | | | | | | | | | | | | +------+ +------+ | +-----------+ | | | | | | +-----------------------------------+ | | +-----------------------------------+ | | | +------+ +------+ +--------------------------+ | | | | | | | +-----------+ | | | +------+ +------+ | | | | | | | | L3 | | | | +------+ +------+ +--+ tag | | | | | | | | | | | | | | +------+ +------+ | +-----------+ | | | | +---------+ +-----------------------------------+ That means spreading tasks among clusters will bring more bandwidth while packing tasks within one cluster will lead to smaller cache synchronization latency. So both kernel and userspace will have a chance to leverage this topology to deploy tasks accordingly to achieve either smaller cache latency within one cluster or an even distribution of load among clusters for higher throughput. This patch exposes cluster topology to both kernel and userspace. Libraried like hwloc will know cluster by cluster_cpus and related sysfs attributes. PoC of HWLOC support at [2]. Note this patch only handle the ACPI case. Special consideration is needed for SMT processors, where it is necessary to move 2 levels up the hierarchy from the leaf nodes (thus skipping the processor core level). Note that arm64 / ACPI does not provide any means of identifying a die level in the topology but that may be unrelate to the cluster level. [1] ACPI Specification 6.3 - section 5.2.29.1 processor hierarchy node structure (Type 0) [2] https://github.com/hisilicon/hwloc/tree/linux-cluster Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> Signed-off-by: Tian Tao <tiantao6@hisilicon.com> Signed-off-by: Barry Song <song.bao.hua@hisilicon.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20210924085104.44806-2-21cnbao@gmail.com
2021-09-24 20:51:02 +12:00
ACPI: PPTT: Leave the table mapped for the runtime usage Currently, everytime an information needs to be fetched from the PPTT, the table is mapped via acpi_get_table() and unmapped after the use via acpi_put_table() which is fine. However we do this at runtime especially when the CPU is hotplugged out and plugged in back since we re-populate the cache topology and other information. However, with the support to fetch LLC information from the PPTT in the cpuhotplug path which is executed in the atomic context, it is preferred to avoid mapping and unmapping of the PPTT for every single use as the acpi_get_table() might sleep waiting for a mutex. In order to avoid the same, the table is needs to just mapped once on the boot CPU and is never unmapped allowing it to be used at runtime with out the hassle of mapping and unmapping the table. Reported-by: Guenter Roeck <linux@roeck-us.net> Cc: Rafael J. Wysocki <rafael@kernel.org> Signed-off-by: Sudeep Holla <sudeep.holla@arm.com> -- Hi Rafael, Sorry to bother you again on this PPTT changes. Guenter reported an issue with lockdep enabled in -next that include my cacheinfo/arch_topology changes to utilise LLC from PPTT in the CPU hotplug path. Please ack the change once you are happy so that I can get it merged with other fixes via Greg's tree. Regards, Sudeep Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Link: https://lore.kernel.org/r/20220720-arch_topo_fixes-v3-2-43d696288e84@arm.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-07-20 13:55:39 +01:00
topology: Represent clusters of CPUs within a die Both ACPI and DT provide the ability to describe additional layers of topology between that of individual cores and higher level constructs such as the level at which the last level cache is shared. In ACPI this can be represented in PPTT as a Processor Hierarchy Node Structure [1] that is the parent of the CPU cores and in turn has a parent Processor Hierarchy Nodes Structure representing a higher level of topology. For example Kunpeng 920 has 6 or 8 clusters in each NUMA node, and each cluster has 4 cpus. All clusters share L3 cache data, but each cluster has local L3 tag. On the other hand, each clusters will share some internal system bus. +-----------------------------------+ +---------+ | +------+ +------+ +--------------------------+ | | | CPU0 | | cpu1 | | +-----------+ | | | +------+ +------+ | | | | | | +----+ L3 | | | | +------+ +------+ cluster | | tag | | | | | CPU2 | | CPU3 | | | | | | | +------+ +------+ | +-----------+ | | | | | | +-----------------------------------+ | | +-----------------------------------+ | | | +------+ +------+ +--------------------------+ | | | | | | | +-----------+ | | | +------+ +------+ | | | | | | | | L3 | | | | +------+ +------+ +----+ tag | | | | | | | | | | | | | | +------+ +------+ | +-----------+ | | | | | | +-----------------------------------+ | L3 | | data | +-----------------------------------+ | | | +------+ +------+ | +-----------+ | | | | | | | | | | | | | +------+ +------+ +----+ L3 | | | | | | tag | | | | +------+ +------+ | | | | | | | | | | | +-----------+ | | | +------+ +------+ +--------------------------+ | +-----------------------------------| | | +-----------------------------------| | | | +------+ +------+ +--------------------------+ | | | | | | | +-----------+ | | | +------+ +------+ | | | | | | +----+ L3 | | | | +------+ +------+ | | tag | | | | | | | | | | | | | | +------+ +------+ | +-----------+ | | | | | | +-----------------------------------+ | | +-----------------------------------+ | | | +------+ +------+ +--------------------------+ | | | | | | | +-----------+ | | | +------+ +------+ | | | | | | | | L3 | | | | +------+ +------+ +---+ tag | | | | | | | | | | | | | | +------+ +------+ | +-----------+ | | | | | | +-----------------------------------+ | | +-----------------------------------+ | | | +------+ +------+ +--------------------------+ | | | | | | | +-----------+ | | | +------+ +------+ | | | | | | | | L3 | | | | +------+ +------+ +--+ tag | | | | | | | | | | | | | | +------+ +------+ | +-----------+ | | | | +---------+ +-----------------------------------+ That means spreading tasks among clusters will bring more bandwidth while packing tasks within one cluster will lead to smaller cache synchronization latency. So both kernel and userspace will have a chance to leverage this topology to deploy tasks accordingly to achieve either smaller cache latency within one cluster or an even distribution of load among clusters for higher throughput. This patch exposes cluster topology to both kernel and userspace. Libraried like hwloc will know cluster by cluster_cpus and related sysfs attributes. PoC of HWLOC support at [2]. Note this patch only handle the ACPI case. Special consideration is needed for SMT processors, where it is necessary to move 2 levels up the hierarchy from the leaf nodes (thus skipping the processor core level). Note that arm64 / ACPI does not provide any means of identifying a die level in the topology but that may be unrelate to the cluster level. [1] ACPI Specification 6.3 - section 5.2.29.1 processor hierarchy node structure (Type 0) [2] https://github.com/hisilicon/hwloc/tree/linux-cluster Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> Signed-off-by: Tian Tao <tiantao6@hisilicon.com> Signed-off-by: Barry Song <song.bao.hua@hisilicon.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20210924085104.44806-2-21cnbao@gmail.com
2021-09-24 20:51:02 +12:00
ACPI: PPTT: Leave the table mapped for the runtime usage Currently, everytime an information needs to be fetched from the PPTT, the table is mapped via acpi_get_table() and unmapped after the use via acpi_put_table() which is fine. However we do this at runtime especially when the CPU is hotplugged out and plugged in back since we re-populate the cache topology and other information. However, with the support to fetch LLC information from the PPTT in the cpuhotplug path which is executed in the atomic context, it is preferred to avoid mapping and unmapping of the PPTT for every single use as the acpi_get_table() might sleep waiting for a mutex. In order to avoid the same, the table is needs to just mapped once on the boot CPU and is never unmapped allowing it to be used at runtime with out the hassle of mapping and unmapping the table. Reported-by: Guenter Roeck <linux@roeck-us.net> Cc: Rafael J. Wysocki <rafael@kernel.org> Signed-off-by: Sudeep Holla <sudeep.holla@arm.com> -- Hi Rafael, Sorry to bother you again on this PPTT changes. Guenter reported an issue with lockdep enabled in -next that include my cacheinfo/arch_topology changes to utilise LLC from PPTT in the CPU hotplug path. Please ack the change once you are happy so that I can get it merged with other fixes via Greg's tree. Regards, Sudeep Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Link: https://lore.kernel.org/r/20220720-arch_topo_fixes-v3-2-43d696288e84@arm.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-07-20 13:55:39 +01:00
topology: Represent clusters of CPUs within a die Both ACPI and DT provide the ability to describe additional layers of topology between that of individual cores and higher level constructs such as the level at which the last level cache is shared. In ACPI this can be represented in PPTT as a Processor Hierarchy Node Structure [1] that is the parent of the CPU cores and in turn has a parent Processor Hierarchy Nodes Structure representing a higher level of topology. For example Kunpeng 920 has 6 or 8 clusters in each NUMA node, and each cluster has 4 cpus. All clusters share L3 cache data, but each cluster has local L3 tag. On the other hand, each clusters will share some internal system bus. +-----------------------------------+ +---------+ | +------+ +------+ +--------------------------+ | | | CPU0 | | cpu1 | | +-----------+ | | | +------+ +------+ | | | | | | +----+ L3 | | | | +------+ +------+ cluster | | tag | | | | | CPU2 | | CPU3 | | | | | | | +------+ +------+ | +-----------+ | | | | | | +-----------------------------------+ | | +-----------------------------------+ | | | +------+ +------+ +--------------------------+ | | | | | | | +-----------+ | | | +------+ +------+ | | | | | | | | L3 | | | | +------+ +------+ +----+ tag | | | | | | | | | | | | | | +------+ +------+ | +-----------+ | | | | | | +-----------------------------------+ | L3 | | data | +-----------------------------------+ | | | +------+ +------+ | +-----------+ | | | | | | | | | | | | | +------+ +------+ +----+ L3 | | | | | | tag | | | | +------+ +------+ | | | | | | | | | | | +-----------+ | | | +------+ +------+ +--------------------------+ | +-----------------------------------| | | +-----------------------------------| | | | +------+ +------+ +--------------------------+ | | | | | | | +-----------+ | | | +------+ +------+ | | | | | | +----+ L3 | | | | +------+ +------+ | | tag | | | | | | | | | | | | | | +------+ +------+ | +-----------+ | | | | | | +-----------------------------------+ | | +-----------------------------------+ | | | +------+ +------+ +--------------------------+ | | | | | | | +-----------+ | | | +------+ +------+ | | | | | | | | L3 | | | | +------+ +------+ +---+ tag | | | | | | | | | | | | | | +------+ +------+ | +-----------+ | | | | | | +-----------------------------------+ | | +-----------------------------------+ | | | +------+ +------+ +--------------------------+ | | | | | | | +-----------+ | | | +------+ +------+ | | | | | | | | L3 | | | | +------+ +------+ +--+ tag | | | | | | | | | | | | | | +------+ +------+ | +-----------+ | | | | +---------+ +-----------------------------------+ That means spreading tasks among clusters will bring more bandwidth while packing tasks within one cluster will lead to smaller cache synchronization latency. So both kernel and userspace will have a chance to leverage this topology to deploy tasks accordingly to achieve either smaller cache latency within one cluster or an even distribution of load among clusters for higher throughput. This patch exposes cluster topology to both kernel and userspace. Libraried like hwloc will know cluster by cluster_cpus and related sysfs attributes. PoC of HWLOC support at [2]. Note this patch only handle the ACPI case. Special consideration is needed for SMT processors, where it is necessary to move 2 levels up the hierarchy from the leaf nodes (thus skipping the processor core level). Note that arm64 / ACPI does not provide any means of identifying a die level in the topology but that may be unrelate to the cluster level. [1] ACPI Specification 6.3 - section 5.2.29.1 processor hierarchy node structure (Type 0) [2] https://github.com/hisilicon/hwloc/tree/linux-cluster Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> Signed-off-by: Tian Tao <tiantao6@hisilicon.com> Signed-off-by: Barry Song <song.bao.hua@hisilicon.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20210924085104.44806-2-21cnbao@gmail.com
2021-09-24 20:51:02 +12:00
ACPI: PPTT: Leave the table mapped for the runtime usage Currently, everytime an information needs to be fetched from the PPTT, the table is mapped via acpi_get_table() and unmapped after the use via acpi_put_table() which is fine. However we do this at runtime especially when the CPU is hotplugged out and plugged in back since we re-populate the cache topology and other information. However, with the support to fetch LLC information from the PPTT in the cpuhotplug path which is executed in the atomic context, it is preferred to avoid mapping and unmapping of the PPTT for every single use as the acpi_get_table() might sleep waiting for a mutex. In order to avoid the same, the table is needs to just mapped once on the boot CPU and is never unmapped allowing it to be used at runtime with out the hassle of mapping and unmapping the table. Reported-by: Guenter Roeck <linux@roeck-us.net> Cc: Rafael J. Wysocki <rafael@kernel.org> Signed-off-by: Sudeep Holla <sudeep.holla@arm.com> -- Hi Rafael, Sorry to bother you again on this PPTT changes. Guenter reported an issue with lockdep enabled in -next that include my cacheinfo/arch_topology changes to utilise LLC from PPTT in the CPU hotplug path. Please ack the change once you are happy so that I can get it merged with other fixes via Greg's tree. Regards, Sudeep Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Link: https://lore.kernel.org/r/20220720-arch_topo_fixes-v3-2-43d696288e84@arm.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-07-20 13:55:39 +01:00
topology: Represent clusters of CPUs within a die Both ACPI and DT provide the ability to describe additional layers of topology between that of individual cores and higher level constructs such as the level at which the last level cache is shared. In ACPI this can be represented in PPTT as a Processor Hierarchy Node Structure [1] that is the parent of the CPU cores and in turn has a parent Processor Hierarchy Nodes Structure representing a higher level of topology. For example Kunpeng 920 has 6 or 8 clusters in each NUMA node, and each cluster has 4 cpus. All clusters share L3 cache data, but each cluster has local L3 tag. On the other hand, each clusters will share some internal system bus. +-----------------------------------+ +---------+ | +------+ +------+ +--------------------------+ | | | CPU0 | | cpu1 | | +-----------+ | | | +------+ +------+ | | | | | | +----+ L3 | | | | +------+ +------+ cluster | | tag | | | | | CPU2 | | CPU3 | | | | | | | +------+ +------+ | +-----------+ | | | | | | +-----------------------------------+ | | +-----------------------------------+ | | | +------+ +------+ +--------------------------+ | | | | | | | +-----------+ | | | +------+ +------+ | | | | | | | | L3 | | | | +------+ +------+ +----+ tag | | | | | | | | | | | | | | +------+ +------+ | +-----------+ | | | | | | +-----------------------------------+ | L3 | | data | +-----------------------------------+ | | | +------+ +------+ | +-----------+ | | | | | | | | | | | | | +------+ +------+ +----+ L3 | | | | | | tag | | | | +------+ +------+ | | | | | | | | | | | +-----------+ | | | +------+ +------+ +--------------------------+ | +-----------------------------------| | | +-----------------------------------| | | | +------+ +------+ +--------------------------+ | | | | | | | +-----------+ | | | +------+ +------+ | | | | | | +----+ L3 | | | | +------+ +------+ | | tag | | | | | | | | | | | | | | +------+ +------+ | +-----------+ | | | | | | +-----------------------------------+ | | +-----------------------------------+ | | | +------+ +------+ +--------------------------+ | | | | | | | +-----------+ | | | +------+ +------+ | | | | | | | | L3 | | | | +------+ +------+ +---+ tag | | | | | | | | | | | | | | +------+ +------+ | +-----------+ | | | | | | +-----------------------------------+ | | +-----------------------------------+ | | | +------+ +------+ +--------------------------+ | | | | | | | +-----------+ | | | +------+ +------+ | | | | | | | | L3 | | | | +------+ +------+ +--+ tag | | | | | | | | | | | | | | +------+ +------+ | +-----------+ | | | | +---------+ +-----------------------------------+ That means spreading tasks among clusters will bring more bandwidth while packing tasks within one cluster will lead to smaller cache synchronization latency. So both kernel and userspace will have a chance to leverage this topology to deploy tasks accordingly to achieve either smaller cache latency within one cluster or an even distribution of load among clusters for higher throughput. This patch exposes cluster topology to both kernel and userspace. Libraried like hwloc will know cluster by cluster_cpus and related sysfs attributes. PoC of HWLOC support at [2]. Note this patch only handle the ACPI case. Special consideration is needed for SMT processors, where it is necessary to move 2 levels up the hierarchy from the leaf nodes (thus skipping the processor core level). Note that arm64 / ACPI does not provide any means of identifying a die level in the topology but that may be unrelate to the cluster level. [1] ACPI Specification 6.3 - section 5.2.29.1 processor hierarchy node structure (Type 0) [2] https://github.com/hisilicon/hwloc/tree/linux-cluster Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> Signed-off-by: Tian Tao <tiantao6@hisilicon.com> Signed-off-by: Barry Song <song.bao.hua@hisilicon.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20210924085104.44806-2-21cnbao@gmail.com
2021-09-24 20:51:02 +12:00