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linux/drivers/block/loop.h

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Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 15:20:36 -07:00
move linux/loop.h to drivers/block Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-05-12 10:14:07 -04:00
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 15:20:36 -07:00
UAPI: (Scripted) Disintegrate include/linux Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Michael Kerrisk <mtk.manpages@gmail.com> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Acked-by: Dave Jones <davej@redhat.com>
2012-10-13 10:46:48 +01:00
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 15:20:36 -07:00
loop: add blk-mq.h include Looks like we pull it in through other ways on x86, but we fail on sparc: In file included from drivers/block/cryptoloop.c:30:0: drivers/block/loop.h:63:24: error: field 'tag_set' has incomplete type struct blk_mq_tag_set tag_set; Add the include to loop.h, kill it from loop.c. Signed-off-by: Jens Axboe <axboe@fb.com>
2015-01-02 15:20:25 -07:00
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 15:20:36 -07:00
[PATCH] sem2mutex: drivers/block/loop.c Semaphore to mutex conversion. The conversion was generated via scripts, and the result was validated automatically via a script as well. Signed-off-by: Ingo Molnar <mingo@elte.hu> Cc: Jens Axboe <axboe@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-23 03:00:38 -08:00
UAPI: (Scripted) Disintegrate include/linux Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Michael Kerrisk <mtk.manpages@gmail.com> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Acked-by: Dave Jones <davej@redhat.com>
2012-10-13 10:46:48 +01:00
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 15:20:36 -07:00
block: loop: fix deadlock between open and remove Commit c76f48eb5c08 ("block: take bd_mutex around delete_partitions in del_gendisk") adds disk->part0->bd_mutex in del_gendisk(), this way causes the following AB/BA deadlock between removing loop and opening loop: 1) loop_control_ioctl(LOOP_CTL_REMOVE) -> mutex_lock(&loop_ctl_mutex) -> del_gendisk -> mutex_lock(&disk->part0->bd_mutex) 2) blkdev_get_by_dev -> mutex_lock(&disk->part0->bd_mutex) -> lo_open -> mutex_lock(&loop_ctl_mutex) Add a new Lo_deleting state to remove the need for clearing ->private_data and thus holding loop_ctl_mutex in the ioctl LOOP_CTL_REMOVE path. Based on an analysis and earlier patch from Ming Lei <ming.lei@redhat.com>. Reported-by: Colin Ian King <colin.king@canonical.com> Fixes: c76f48eb5c08 ("block: take bd_mutex around delete_partitions in del_gendisk") Signed-off-by: Christoph Hellwig <hch@lst.de> Tested-by: Colin Ian King <colin.king@canonical.com> Reviewed-by: Ming Lei <ming.lei@redhat.com> Link: https://lore.kernel.org/r/20210605140950.5800-1-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-05 17:09:50 +03:00
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 15:20:36 -07:00
block: loop: don't hold lo_ctl_mutex in lo_open The lo_ctl_mutex is held for running all ioctl handlers, and in some ioctl handlers, ioctl_by_bdev(BLKRRPART) is called for rereading partitions, which requires bd_mutex. So it is easy to cause failure because trylock(bd_mutex) may fail inside blkdev_reread_part(), and follows the lock context: blkid or other application: ->open() ->mutex_lock(bd_mutex) ->lo_open() ->mutex_lock(lo_ctl_mutex) losetup(set fd ioctl): ->mutex_lock(lo_ctl_mutex) ->ioctl_by_bdev(BLKRRPART) ->trylock(bd_mutex) This patch trys to eliminate the ABBA lock dependency by removing lo_ctl_mutext in lo_open() with the following approach: 1) make lo_refcnt as atomic_t and avoid acquiring lo_ctl_mutex in lo_open(): - for open vs. add/del loop, no any problem because of loop_index_mutex - freeze request queue during clr_fd, so I/O can't come until clearing fd is completed, like the effect of holding lo_ctl_mutex in lo_open - both open() and release() have been serialized by bd_mutex already 2) don't hold lo_ctl_mutex for decreasing/checking lo_refcnt in lo_release(), then lo_ctl_mutex is only required for the last release. Reviewed-by: Christoph Hellwig <hch@lst.de> Tested-by: Jarod Wilson <jarod@redhat.com> Acked-by: Jarod Wilson <jarod@redhat.com> Signed-off-by: Ming Lei <ming.lei@canonical.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-06 12:26:23 +08:00
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 15:20:36 -07:00
userns: Convert loop to use kuid_t instead of uid_t Cc: Jens Axboe <jaxboe@fusionio.com> Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
2012-02-11 11:23:51 -08:00
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 15:20:36 -07:00
[PATCH] gfp_t: remaining bits of drivers/* Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-21 03:22:34 -04:00
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 15:20:36 -07:00
loop: use worker per cgroup instead of kworker Patch series "Charge loop device i/o to issuing cgroup", v14. The loop device runs all i/o to the backing file on a separate kworker thread which results in all i/o being charged to the root cgroup. This allows a loop device to be used to trivially bypass resource limits and other policy. This patch series fixes this gap in accounting. A simple script to demonstrate this behavior on cgroupv2 machine: ''' #!/bin/bash set -e CGROUP=/sys/fs/cgroup/test.slice LOOP_DEV=/dev/loop0 if [[ ! -d $CGROUP ]] then sudo mkdir $CGROUP fi grep oom_kill $CGROUP/memory.events # Set a memory limit, write more than that limit to tmpfs -> OOM kill sudo unshare -m bash -c " echo \$\$ > $CGROUP/cgroup.procs; echo 0 > $CGROUP/memory.swap.max; echo 64M > $CGROUP/memory.max; mount -t tmpfs -o size=512m tmpfs /tmp; dd if=/dev/zero of=/tmp/file bs=1M count=256" || true grep oom_kill $CGROUP/memory.events # Set a memory limit, write more than that limit through loopback # device -> no OOM kill sudo unshare -m bash -c " echo \$\$ > $CGROUP/cgroup.procs; echo 0 > $CGROUP/memory.swap.max; echo 64M > $CGROUP/memory.max; mount -t tmpfs -o size=512m tmpfs /tmp; truncate -s 512m /tmp/backing_file losetup $LOOP_DEV /tmp/backing_file dd if=/dev/zero of=$LOOP_DEV bs=1M count=256; losetup -D $LOOP_DEV" || true grep oom_kill $CGROUP/memory.events ''' Naively charging cgroups could result in priority inversions through the single kworker thread in the case where multiple cgroups are reading/writing to the same loop device. This patch series does some minor modification to the loop driver so that each cgroup can make forward progress independently to avoid this inversion. With this patch series applied, the above script triggers OOM kills when writing through the loop device as expected. This patch (of 3): Existing uses of loop device may have multiple cgroups reading/writing to the same device. Simply charging resources for I/O to the backing file could result in priority inversion where one cgroup gets synchronously blocked, holding up all other I/O to the loop device. In order to avoid this priority inversion, we use a single workqueue where each work item is a "struct loop_worker" which contains a queue of struct loop_cmds to issue. The loop device maintains a tree mapping blk css_id -> loop_worker. This allows each cgroup to independently make forward progress issuing I/O to the backing file. There is also a single queue for I/O associated with the rootcg which can be used in cases of extreme memory shortage where we cannot allocate a loop_worker. The locking for the tree and queues is fairly heavy handed - we acquire a per-loop-device spinlock any time either is accessed. The existing implementation serializes all I/O through a single thread anyways, so I don't believe this is any worse. [colin.king@canonical.com: fixes] Link: https://lkml.kernel.org/r/20210610173944.1203706-1-schatzberg.dan@gmail.com Link: https://lkml.kernel.org/r/20210610173944.1203706-2-schatzberg.dan@gmail.com Signed-off-by: Dan Schatzberg <schatzberg.dan@gmail.com> Reviewed-by: Ming Lei <ming.lei@redhat.com> Acked-by: Jens Axboe <axboe@kernel.dk> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Chris Down <chris@chrisdown.name> Cc: Shakeel Butt <shakeelb@google.com> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-06-28 19:38:15 -07:00
block: loop: prepare for supporing direct IO This patches provides one interface for enabling direct IO from user space: - userspace(such as losetup) can pass 'file' which is opened/fcntl as O_DIRECT Also __loop_update_dio() is introduced to check if direct I/O can be used on current loop setting. The last big change is to introduce LO_FLAGS_DIRECT_IO flag for userspace to know if direct IO is used to access backing file. Cc: linux-api@vger.kernel.org Signed-off-by: Ming Lei <ming.lei@canonical.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-08-17 10:31:49 +08:00
loop: remember whether sysfs_create_group() was done syzbot is hitting WARN() triggered by memory allocation fault injection [1] because loop module is calling sysfs_remove_group() when sysfs_create_group() failed. Fix this by remembering whether sysfs_create_group() succeeded. [1] https://syzkaller.appspot.com/bug?id=3f86c0edf75c86d2633aeb9dd69eccc70bc7e90b Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Reported-by: syzbot <syzbot+9f03168400f56df89dbc6f1751f4458fe739ff29@syzkaller.appspotmail.com> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Renamed sysfs_ready -> sysfs_inited. Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-05-04 10:58:09 -06:00
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 15:20:36 -07:00
loop.h build fix include/linux/loop.h:66: error: expected specifier-qualifier-list before 'request_queue_t' Cc: Sebastian Siewior <sebastian@breakpoint.cc> Cc: Jens Axboe <jens.axboe@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-23 18:44:00 -07:00
block: loop: improve performance via blk-mq The conversion is a bit straightforward, and use work queue to dispatch requests of loop block, and one big change is that requests is submitted to backend file/device concurrently with work queue, so throughput may get improved much. Given write requests over same file are often run exclusively, so don't handle them concurrently for avoiding extra context switch cost, possible lock contention and work schedule cost. Also with blk-mq, there is opportunity to get loop I/O merged before submitting to backend file/device. In the following test: - base: v3.19-rc2-2041231 - loop over file in ext4 file system on SSD disk - bs: 4k, libaio, io depth: 64, O_DIRECT, num of jobs: 1 - throughput: IOPS ------------------------------------------------------ | | base | base with loop-mq | delta | ------------------------------------------------------ | randread | 1740 | 25318 | +1355%| ------------------------------------------------------ | read | 42196 | 51771 | +22.6%| ----------------------------------------------------- | randwrite | 35709 | 34624 | -3% | ----------------------------------------------------- | write | 39137 | 40326 | +3% | ----------------------------------------------------- So loop-mq can improve throughput for both read and randread, meantime, performance of write and randwrite isn't hurted basically. Another benefit is that loop driver code gets simplified much after blk-mq conversion, and the patch can be thought as cleanup too. Signed-off-by: Ming Lei <ming.lei@canonical.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2014-12-31 13:22:57 +00:00
remove artificial software max_loop limit Remove artificial maximum 256 loop device that can be created due to a legacy device number limit. Searching through lkml archive, there are several instances where users complained about the artificial limit that the loop driver impose. There is no reason to have such limit. This patch rid the limit entirely and make loop device and associated block queue instantiation on demand. With on-demand instantiation, it also gives the benefit of not wasting memory if these devices are not in use (compare to current implementation that always create 8 loop devices), a net improvement in both areas. This version is both tested with creation of large number of loop devices and is compatible with existing losetup/mount user land tools. There are a number of people who worked on this and provided valuable suggestions, in no particular order, by: Jens Axboe Jan Engelhardt Christoph Hellwig Thomas M Signed-off-by: Ken Chen <kenchen@google.com> Cc: Jan Engelhardt <jengelh@linux01.gwdg.de> Cc: Christoph Hellwig <hch@lst.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-08 00:28:20 -07:00
loop: scale loop device by introducing per device lock Currently, loop device has only one global lock: loop_ctl_mutex. This becomes hot in scenarios where many loop devices are used. Scale it by introducing per-device lock: lo_mutex that protects modifications of all fields in struct loop_device. Keep loop_ctl_mutex to protect global data: loop_index_idr, loop_lookup, loop_add. The new lock ordering requirement is that loop_ctl_mutex must be taken before lo_mutex. Signed-off-by: Pavel Tatashin <pasha.tatashin@soleen.com> Reviewed-by: Tyler Hicks <tyhicks@linux.microsoft.com> Reviewed-by: Petr Vorel <pvorel@suse.cz> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-01-26 09:46:30 -05:00
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 15:20:36 -07:00
block: loop: improve performance via blk-mq The conversion is a bit straightforward, and use work queue to dispatch requests of loop block, and one big change is that requests is submitted to backend file/device concurrently with work queue, so throughput may get improved much. Given write requests over same file are often run exclusively, so don't handle them concurrently for avoiding extra context switch cost, possible lock contention and work schedule cost. Also with blk-mq, there is opportunity to get loop I/O merged before submitting to backend file/device. In the following test: - base: v3.19-rc2-2041231 - loop over file in ext4 file system on SSD disk - bs: 4k, libaio, io depth: 64, O_DIRECT, num of jobs: 1 - throughput: IOPS ------------------------------------------------------ | | base | base with loop-mq | delta | ------------------------------------------------------ | randread | 1740 | 25318 | +1355%| ------------------------------------------------------ | read | 42196 | 51771 | +22.6%| ----------------------------------------------------- | randwrite | 35709 | 34624 | -3% | ----------------------------------------------------- | write | 39137 | 40326 | +3% | ----------------------------------------------------- So loop-mq can improve throughput for both read and randread, meantime, performance of write and randwrite isn't hurted basically. Another benefit is that loop driver code gets simplified much after blk-mq conversion, and the patch can be thought as cleanup too. Signed-off-by: Ming Lei <ming.lei@canonical.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2014-12-31 13:22:57 +00:00
loop: use worker per cgroup instead of kworker Patch series "Charge loop device i/o to issuing cgroup", v14. The loop device runs all i/o to the backing file on a separate kworker thread which results in all i/o being charged to the root cgroup. This allows a loop device to be used to trivially bypass resource limits and other policy. This patch series fixes this gap in accounting. A simple script to demonstrate this behavior on cgroupv2 machine: ''' #!/bin/bash set -e CGROUP=/sys/fs/cgroup/test.slice LOOP_DEV=/dev/loop0 if [[ ! -d $CGROUP ]] then sudo mkdir $CGROUP fi grep oom_kill $CGROUP/memory.events # Set a memory limit, write more than that limit to tmpfs -> OOM kill sudo unshare -m bash -c " echo \$\$ > $CGROUP/cgroup.procs; echo 0 > $CGROUP/memory.swap.max; echo 64M > $CGROUP/memory.max; mount -t tmpfs -o size=512m tmpfs /tmp; dd if=/dev/zero of=/tmp/file bs=1M count=256" || true grep oom_kill $CGROUP/memory.events # Set a memory limit, write more than that limit through loopback # device -> no OOM kill sudo unshare -m bash -c " echo \$\$ > $CGROUP/cgroup.procs; echo 0 > $CGROUP/memory.swap.max; echo 64M > $CGROUP/memory.max; mount -t tmpfs -o size=512m tmpfs /tmp; truncate -s 512m /tmp/backing_file losetup $LOOP_DEV /tmp/backing_file dd if=/dev/zero of=$LOOP_DEV bs=1M count=256; losetup -D $LOOP_DEV" || true grep oom_kill $CGROUP/memory.events ''' Naively charging cgroups could result in priority inversions through the single kworker thread in the case where multiple cgroups are reading/writing to the same loop device. This patch series does some minor modification to the loop driver so that each cgroup can make forward progress independently to avoid this inversion. With this patch series applied, the above script triggers OOM kills when writing through the loop device as expected. This patch (of 3): Existing uses of loop device may have multiple cgroups reading/writing to the same device. Simply charging resources for I/O to the backing file could result in priority inversion where one cgroup gets synchronously blocked, holding up all other I/O to the loop device. In order to avoid this priority inversion, we use a single workqueue where each work item is a "struct loop_worker" which contains a queue of struct loop_cmds to issue. The loop device maintains a tree mapping blk css_id -> loop_worker. This allows each cgroup to independently make forward progress issuing I/O to the backing file. There is also a single queue for I/O associated with the rootcg which can be used in cases of extreme memory shortage where we cannot allocate a loop_worker. The locking for the tree and queues is fairly heavy handed - we acquire a per-loop-device spinlock any time either is accessed. The existing implementation serializes all I/O through a single thread anyways, so I don't believe this is any worse. [colin.king@canonical.com: fixes] Link: https://lkml.kernel.org/r/20210610173944.1203706-1-schatzberg.dan@gmail.com Link: https://lkml.kernel.org/r/20210610173944.1203706-2-schatzberg.dan@gmail.com Signed-off-by: Dan Schatzberg <schatzberg.dan@gmail.com> Reviewed-by: Ming Lei <ming.lei@redhat.com> Acked-by: Jens Axboe <axboe@kernel.dk> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Chris Down <chris@chrisdown.name> Cc: Shakeel Butt <shakeelb@google.com> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-06-28 19:38:15 -07:00
loop: remove union of use_aio and ref in struct loop_cmd When the request is completed, lo_complete_rq() checks cmd->use_aio. However, if this is in fact an aio request, cmd->use_aio will have already been reused as cmd->ref by lo_rw_aio*. Fix it by not using a union. On x86_64, there's a hole after the union anyways, so this doesn't make struct loop_cmd any bigger. Fixes: 92d773324b7e ("block/loop: fix use after free") Signed-off-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-09-20 14:24:34 -07:00
loop: zero-fill bio on the submitting cpu In thruth I've just audited which blk-mq drivers don't currently have a complete callback, but I think this change is at least borderline useful. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2017-04-20 16:03:02 +02:00
block: loop: support DIO & AIO There are at least 3 advantages to use direct I/O and AIO on read/write loop's backing file: 1) double cache can be avoided, then memory usage gets decreased a lot 2) not like user space direct I/O, there isn't cost of pinning pages 3) avoid context switch for obtaining good throughput - in buffered file read, random I/O top throughput is often obtained only if they are submitted concurrently from lots of tasks; but for sequential I/O, most of times they can be hit from page cache, so concurrent submissions often introduce unnecessary context switch and can't improve throughput much. There was such discussion[1] to use non-blocking I/O to improve the problem for application. - with direct I/O and AIO, concurrent submissions can be avoided and random read throughput can't be affected meantime xfstests(-g auto, ext4) is basically passed when running with direct I/O(aio), one exception is generic/232, but it failed in loop buffered I/O(4.2-rc6-next-20150814) too. Follows the fio test result for performance purpose: 4 jobs fio test inside ext4 file system over loop block 1) How to run - KVM: 4 VCPUs, 2G RAM - linux kernel: 4.2-rc6-next-20150814(base) with the patchset - the loop block is over one image on SSD. - linux psync, 4 jobs, size 1500M, ext4 over loop block - test result: IOPS from fio output 2) Throughput(IOPS) becomes a bit better with direct I/O(aio) ------------------------------------------------------------- test cases |randread |read |randwrite |write | ------------------------------------------------------------- base |8015 |113811 |67442 |106978 ------------------------------------------------------------- base+loop aio |8136 |125040 |67811 |111376 ------------------------------------------------------------- - somehow, it should be caused by more page cache avaiable for application or one extra page copy is avoided in case of direct I/O 3) context switch - context switch decreased by ~50% with loop direct I/O(aio) compared with loop buffered I/O(4.2-rc6-next-20150814) 4) memory usage from /proc/meminfo ------------------------------------------------------------- | Buffers | Cached ------------------------------------------------------------- base | > 760MB | ~950MB ------------------------------------------------------------- base+loop direct I/O(aio) | < 5MB | ~1.6GB ------------------------------------------------------------- - so there are much more page caches available for application with direct I/O [1] https://lwn.net/Articles/612483/ Signed-off-by: Ming Lei <ming.lei@canonical.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-08-17 10:31:51 +08:00
block/loop: allow request merge for directio mode Currently loop disables merge. While it makes sense for buffer IO mode, directio mode can benefit from request merge. Without merge, loop could send small size IO to underlayer disk and harm performance. Reviewed-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Shaohua Li <shli@fb.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-08-31 22:09:46 -07:00
loop: charge i/o to mem and blk cg The current code only associates with the existing blkcg when aio is used to access the backing file. This patch covers all types of i/o to the backing file and also associates the memcg so if the backing file is on tmpfs, memory is charged appropriately. This patch also exports cgroup_get_e_css and int_active_memcg so it can be used by the loop module. Link: https://lkml.kernel.org/r/20210610173944.1203706-4-schatzberg.dan@gmail.com Signed-off-by: Dan Schatzberg <schatzberg.dan@gmail.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Jens Axboe <axboe@kernel.dk> Cc: Chris Down <chris@chrisdown.name> Cc: Michal Hocko <mhocko@suse.com> Cc: Ming Lei <ming.lei@redhat.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-06-28 19:38:21 -07:00
block: loop: improve performance via blk-mq The conversion is a bit straightforward, and use work queue to dispatch requests of loop block, and one big change is that requests is submitted to backend file/device concurrently with work queue, so throughput may get improved much. Given write requests over same file are often run exclusively, so don't handle them concurrently for avoiding extra context switch cost, possible lock contention and work schedule cost. Also with blk-mq, there is opportunity to get loop I/O merged before submitting to backend file/device. In the following test: - base: v3.19-rc2-2041231 - loop over file in ext4 file system on SSD disk - bs: 4k, libaio, io depth: 64, O_DIRECT, num of jobs: 1 - throughput: IOPS ------------------------------------------------------ | | base | base with loop-mq | delta | ------------------------------------------------------ | randread | 1740 | 25318 | +1355%| ------------------------------------------------------ | read | 42196 | 51771 | +22.6%| ----------------------------------------------------- | randwrite | 35709 | 34624 | -3% | ----------------------------------------------------- | write | 39137 | 40326 | +3% | ----------------------------------------------------- So loop-mq can improve throughput for both read and randread, meantime, performance of write and randwrite isn't hurted basically. Another benefit is that loop driver code gets simplified much after blk-mq conversion, and the patch can be thought as cleanup too. Signed-off-by: Ming Lei <ming.lei@canonical.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2014-12-31 13:22:57 +00:00
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 15:20:36 -07:00