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Rafael J. Wysocki e0560219db cpufreq: intel_pstate: Use HWP to initialize ITMT if CPPC is missing 
commit a1ff59784b upstream.

It is reported that single-thread performance on some hybrid systems
dropped significantly after commit 7feec7430e ("ACPI: CPPC: Only probe
for _CPC if CPPC v2 is acked") which prevented _CPC from being used if
the support for it had not been confirmed by the platform firmware.

The problem is that if the platform firmware does not confirm CPPC v2
support, cppc_get_perf_caps() returns an error which prevents the
intel_pstate driver from enabling ITMT.  Consequently, the scheduler
does not get any hints on CPU performance differences, so in a hybrid
system some tasks may run on CPUs with lower capacity even though they
should be running on high-capacity CPUs.

To address this, modify intel_pstate to use the information from
MSR_HWP_CAPABILITIES to enable ITMT if CPPC is not available (which is
done already if the highest performance number coming from CPPC is not
realistic).

Fixes: 7feec7430e ("ACPI: CPPC: Only probe for _CPC if CPPC v2 is acked")
Closes: https://lore.kernel.org/linux-acpi/d01b0a1f-bd33-47fe-ab41-43843d8a374f@kfocus.org
Link: https://lore.kernel.org/linux-acpi/ZnD22b3Br1ng7alf@kf-XE
Reported-by: Aaron Rainbolt <arainbolt@kfocus.org>
Tested-by: Aaron Rainbolt <arainbolt@kfocus.org>
Cc: 5.19+ <stable@vger.kernel.org> # 5.19+
Link: https://patch.msgid.link/12460110.O9o76ZdvQC@rjwysocki.net
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2024-07-05 09:31:56 +02:00
arch Revert "MIPS: pci: lantiq: restore reset gpio polarity" 2024-07-05 09:31:51 +02:00
block block/ioctl: prefer different overflow check 2024-06-27 13:46:15 +02:00
certs certs: Fix build error when PKCS#11 URI contains semicolon 2023-02-09 11:28:11 +01:00
crypto crypto: ecdh - explicitly zeroize private_key 2024-07-05 09:31:49 +02:00
Documentation dt-bindings: i2c: atmel,at91sam: correct path to i2c-controller schema 2024-07-05 09:31:44 +02:00
drivers cpufreq: intel_pstate: Use HWP to initialize ITMT if CPPC is missing 2024-07-05 09:31:56 +02:00
fs nfs: drop the incorrect assertion in nfs_swap_rw() 2024-07-05 09:31:52 +02:00
include nvme: fixup comment for nvme RDMA Provider Type 2024-07-05 09:31:50 +02:00
init smp: Provide 'setup_max_cpus' definition on UP too 2024-06-16 13:41:42 +02:00
io_uring io_uring/sqpoll: work around a potential audit memory leak 2024-06-27 13:46:14 +02:00
ipc ipc: fix memory leak in init_mqueue_fs() 2022-12-31 13:32:01 +01:00
kernel bpf: Mark bpf prog stack with kmsan_unposion_memory in interpreter mode 2024-07-05 09:31:48 +02:00
lib maple_tree: fix mas_empty_area_rev() null pointer dereference 2024-06-16 13:41:31 +02:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm mm/page_table_check: fix crash on ZONE_DEVICE 2024-06-27 13:46:22 +02:00
net net: can: j1939: enhanced error handling for tightly received RTS messages in xtp_rx_rts_session_new 2024-07-05 09:31:56 +02:00
rust rust: macros: fix soundness issue in module! macro 2024-05-17 11:56:17 +02:00
samples work around gcc bugs with 'asm goto' with outputs 2024-02-23 09:12:28 +01:00
scripts scripts/gdb: fix SB_* constants parsing 2024-06-16 13:41:32 +02:00
security ima: Fix use-after-free on a dentry's dname.name 2024-07-05 09:31:51 +02:00
sound ALSA: hda/realtek: fix mute/micmute LEDs don't work for EliteBook 645/665 G11. 2024-07-05 09:31:56 +02:00
tools perf script: Show also errors for --insn-trace option 2024-06-27 13:46:23 +02:00
usr usr/gen_init_cpio.c: remove unnecessary -1 values from int file 2022-10-03 14:21:44 -07:00
virt KVM: Fix a data race on last_boosted_vcpu in kvm_vcpu_on_spin() 2024-06-27 13:46:21 +02:00
.clang-format inet: ping: use hlist_nulls rcu iterator during lookup 2022-12-01 12:42:46 +01:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore Kbuild: add Rust support 2022-09-28 09:02:20 +02:00
.mailmap 9 hotfixes. 6 for MM, 3 for other areas. Four of these patches address 2022-12-10 17:10:52 -08:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Remove Michal Marek from Kbuild maintainers 2022-11-16 14:53:00 +09:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS MAINTAINERS: add leah to 6.1 MAINTAINERS file 2024-05-17 11:56:16 +02:00
Makefile Linux 6.1.96 2024-06-27 13:46:24 +02:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.