- 15 1月, 2020 3 次提交
-
-
由 Joseph Qi 提交于
Add 2 interfaces to stat io throttle information: blkio.throttle.total_io_queued blkio.throttle.total_bytes_queued These interfaces are used for monitoring throttled io/bytes and analyzing if delay has relation with io throttle. Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com> Reviewed-by: NGavin Shan <shan.gavin@linux.alibaba.com> Reviewed-by: NJiufei Xue <jiufei.xue@linux.alibaba.com> Reviewed-by: NXiaoguang Wang <xiaoguang.wang@linux.alibaba.com> Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>
-
由 Joseph Qi 提交于
io throtl stats will blkg_get at the beginning of throttle and then blkg_put at the new introduced bi_tg_end_io. This will cause blkg to be freed if end_io is called twice like dm-thin, which will save origin end_io first, and call its overwrite end_io and then the saved end_io. After that, access blkg is invalid and finally BUG: [ 4417.235048] BUG: unable to handle kernel NULL pointer dereference at 00000000000001e0 [ 4417.236475] IP: [<ffffffff812e7c71>] throtl_update_dispatch_stats+0x21/0xb0 [ 4417.237865] PGD 98395067 PUD 362e1067 PMD 0 [ 4417.239232] Oops: 0000 [#1] SMP ...... [ 4417.274070] Call Trace: [ 4417.275407] [<ffffffff812ea93d>] blk_throtl_bio+0xfd/0x630 [ 4417.276760] [<ffffffff810b3613>] ? wake_up_process+0x23/0x40 [ 4417.278079] [<ffffffff81094c04>] ? wake_up_worker+0x24/0x30 [ 4417.279387] [<ffffffff81095772>] ? insert_work+0x62/0xa0 [ 4417.280697] [<ffffffff8116c2c7>] ? mempool_free_slab+0x17/0x20 [ 4417.282019] [<ffffffff8116c6c9>] ? mempool_free+0x49/0x90 [ 4417.283326] [<ffffffff812c9acf>] generic_make_request_checks+0x16f/0x360 [ 4417.284637] [<ffffffffa0340d97>] ? thin_map+0x227/0x2c0 [dm_thin_pool] [ 4417.285951] [<ffffffff812c9ce7>] generic_make_request+0x27/0x130 [ 4417.287240] [<ffffffffa0230b3d>] __map_bio+0xad/0x100 [dm_mod] [ 4417.288503] [<ffffffffa023257e>] __clone_and_map_data_bio+0x15e/0x240 [dm_mod] [ 4417.289778] [<ffffffffa02329ea>] __split_and_process_bio+0x38a/0x500 [dm_mod] [ 4417.291062] [<ffffffffa0232c91>] dm_make_request+0x131/0x1a0 [dm_mod] [ 4417.292344] [<ffffffff812c9da2>] generic_make_request+0xe2/0x130 [ 4417.293626] [<ffffffff812c9e61>] submit_bio+0x71/0x150 [ 4417.294909] [<ffffffff8121ab1d>] ? bio_alloc_bioset+0x20d/0x360 [ 4417.296195] [<ffffffff81215acb>] _submit_bh+0x14b/0x220 [ 4417.297484] [<ffffffff81215bb0>] submit_bh+0x10/0x20 [ 4417.298744] [<ffffffffa016d8d8>] jbd2_journal_commit_transaction+0x6c8/0x19a0 [jbd2] [ 4417.300014] [<ffffffff810135b8>] ? __switch_to+0xf8/0x4c0 [ 4417.301268] [<ffffffffa01731e9>] kjournald2+0xc9/0x270 [jbd2] [ 4417.302524] [<ffffffff810a0fd0>] ? wake_up_atomic_t+0x30/0x30 [ 4417.303753] [<ffffffffa0173120>] ? commit_timeout+0x10/0x10 [jbd2] [ 4417.304950] [<ffffffff8109ffef>] kthread+0xcf/0xe0 [ 4417.306107] [<ffffffff8109ff20>] ? kthread_create_on_node+0x140/0x140 [ 4417.307255] [<ffffffff81647f18>] ret_from_fork+0x58/0x90 [ 4417.308349] [<ffffffff8109ff20>] ? kthread_create_on_node+0x140/0x140 ...... Now we introduce a new bio flag BIO_THROTL_STATED to make sure blkg_get/put only get called once for the same bio. Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com> Reviewed-by: NJiufei Xue <jiufei.xue@linux.alibaba.com> Reviewed-by: NXiaoguang Wang <xiaoguang.wang@linux.alibaba.com> Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>
-
由 Joseph Qi 提交于
Add blkio.throttle.io_service_time and blkio.throttle.io_wait_time to get per-cgroup io delay statistics. io_service_time represents the time spent after io throttle to io completion, while io_wait_time represents the time spent on throttle queue. Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com> Reviewed-by: NJiufei Xue <jiufei.xue@linux.alibaba.com> Reviewed-by: NXiaoguang Wang <xiaoguang.wang@linux.alibaba.com> Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>
-
- 27 12月, 2019 2 次提交
-
-
由 Tejun Heo 提交于
commit cf09a8ee19ad1f78b4e18cdde9f2a61133efacf5 upstream. Instead of @node, pass in @q and @blkcg so that the alloc function has more context. This doesn't cause any behavior change and will be used by io.weight implementation. Signed-off-by: NTejun Heo <tj@kernel.org> Signed-off-by: NJens Axboe <axboe@kernel.dk> [Joseph: resolve conflicts for cfq] Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com> Signed-off-by: NJiufei Xue <jiufei.xue@linux.alibaba.com> Reviewed-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
-
由 Joseph Qi 提交于
ECI may have an use case that configuring each device mapper disk throttling policy just under root blkio cgroup, but actually using them in different containers. Since hierarchical throttling is now only supported on cgroup v2 and ECI uses cgroup v1, so we have to enable hierarchical throttling on cgroup v1. This is ported from redhat 7u, and a year ago Jiufei already ported it to alikernel 4.9 as well. So I think this change should be acceptable. Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com> Reviewed-by: NJiufei Xue <jiufei.xue@linux.alibaba.com>
-
- 26 7月, 2019 1 次提交
-
-
由 Konstantin Khlebnikov 提交于
commit 3a10f999ffd464d01c5a05592a15470a3c4bbc36 upstream. After commit 991f61fe ("Blk-throttle: reduce tail io latency when iops limit is enforced") wait time could be zero even if group is throttled and cannot issue requests right now. As a result throtl_select_dispatch() turns into busy-loop under irq-safe queue spinlock. Fix is simple: always round up target time to the next throttle slice. Fixes: 991f61fe ("Blk-throttle: reduce tail io latency when iops limit is enforced") Signed-off-by: NKonstantin Khlebnikov <khlebnikov@yandex-team.ru> Cc: stable@vger.kernel.org # v4.19+ Signed-off-by: NJens Axboe <axboe@kernel.dk> Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
-
- 01 9月, 2018 1 次提交
-
-
由 Dennis Zhou (Facebook) 提交于
There is a very small change a bio gets caught up in a really unfortunate race between a task migration, cgroup exiting, and itself trying to associate with a blkg. This is due to css offlining being performed after the css->refcnt is killed which triggers removal of blkgs that reach their blkg->refcnt of 0. To avoid this, association with a blkg should use tryget and fallback to using the root_blkg. Fixes: 08e18eab ("block: add bi_blkg to the bio for cgroups") Reviewed-by: NJosef Bacik <josef@toxicpanda.com> Signed-off-by: NDennis Zhou <dennisszhou@gmail.com> Cc: Jiufei Xue <jiufei.xue@linux.alibaba.com> Cc: Joseph Qi <joseph.qi@linux.alibaba.com> Cc: Tejun Heo <tj@kernel.org> Cc: Josef Bacik <josef@toxicpanda.com> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: NJens Axboe <axboe@kernel.dk>
-
- 10 8月, 2018 1 次提交
-
-
由 Liu Bo 提交于
When an application's iops has exceeded its cgroup's iops limit, surely it is throttled and kernel will set a timer for dispatching, thus IO latency includes the delay. However, the dispatch delay which is calculated by the limit and the elapsed jiffies is suboptimal. As the dispatch delay is only calculated once the application's iops is (iops limit + 1), it doesn't need to wait any longer than the remaining time of the current slice. The difference can be proved by the following fio job and cgroup iops setting, ----- $ echo 4 > /mnt/config/nullb/disk1/mbps # limit nullb's bandwidth to 4MB/s for testing. $ echo "253:1 riops=100 rbps=max" > /sys/fs/cgroup/unified/cg1/io.max $ cat r2.job [global] name=fio-rand-read filename=/dev/nullb1 rw=randread bs=4k direct=1 numjobs=1 time_based=1 runtime=60 group_reporting=1 [file1] size=4G ioengine=libaio iodepth=1 rate_iops=50000 norandommap=1 thinktime=4ms ----- wo patch: file1: (g=0): rw=randread, bs=(R) 4096B-4096B, (W) 4096B-4096B, (T) 4096B-4096B, ioengine=libaio, iodepth=1 fio-3.7-66-gedfc Starting 1 process read: IOPS=99, BW=400KiB/s (410kB/s)(23.4MiB/60001msec) slat (usec): min=10, max=336, avg=27.71, stdev=17.82 clat (usec): min=2, max=28887, avg=5929.81, stdev=7374.29 lat (usec): min=24, max=28901, avg=5958.73, stdev=7366.22 clat percentiles (usec): | 1.00th=[ 4], 5.00th=[ 4], 10.00th=[ 4], 20.00th=[ 4], | 30.00th=[ 4], 40.00th=[ 4], 50.00th=[ 6], 60.00th=[11731], | 70.00th=[11863], 80.00th=[11994], 90.00th=[12911], 95.00th=[22676], | 99.00th=[23725], 99.50th=[23987], 99.90th=[23987], 99.95th=[25035], | 99.99th=[28967] w/ patch: file1: (g=0): rw=randread, bs=(R) 4096B-4096B, (W) 4096B-4096B, (T) 4096B-4096B, ioengine=libaio, iodepth=1 fio-3.7-66-gedfc Starting 1 process read: IOPS=100, BW=400KiB/s (410kB/s)(23.4MiB/60005msec) slat (usec): min=10, max=155, avg=23.24, stdev=16.79 clat (usec): min=2, max=12393, avg=5961.58, stdev=5959.25 lat (usec): min=23, max=12412, avg=5985.91, stdev=5951.92 clat percentiles (usec): | 1.00th=[ 3], 5.00th=[ 3], 10.00th=[ 4], 20.00th=[ 4], | 30.00th=[ 4], 40.00th=[ 5], 50.00th=[ 47], 60.00th=[11863], | 70.00th=[11994], 80.00th=[11994], 90.00th=[11994], 95.00th=[11994], | 99.00th=[11994], 99.50th=[11994], 99.90th=[12125], 99.95th=[12125], | 99.99th=[12387] Signed-off-by: NLiu Bo <bo.liu@linux.alibaba.com> Signed-off-by: NJens Axboe <axboe@kernel.dk>
-
- 09 7月, 2018 2 次提交
-
-
由 Josef Bacik 提交于
Currently io.low uses a bi_cg_private to stash its private data for the blkg, however other blkcg policies may want to use this as well. Since we can get the private data out of the blkg, move this to bi_blkg in the bio and make it generic, then we can use bio_associate_blkg() to attach the blkg to the bio. Theoretically we could simply replace the bi_css with this since we can get to all the same information from the blkg, however you have to lookup the blkg, so for example wbc_init_bio() would have to lookup and possibly allocate the blkg for the css it was trying to attach to the bio. This could be problematic and result in us either not attaching the css at all to the bio, or falling back to the root blkcg if we are unable to allocate the corresponding blkg. So for now do this, and in the future if possible we could just replace the bi_css with bi_blkg and update the helpers to do the correct translation. Signed-off-by: NJosef Bacik <jbacik@fb.com> Acked-by: NTejun Heo <tj@kernel.org> Signed-off-by: NJens Axboe <axboe@kernel.dk>
-
由 Liu Bo 提交于
Once one cgroup has io.low configured, @low_valid becomes true and other cgroups won't switch it back whatsoever. Signed-off-by: NLiu Bo <bo.liu@linux.alibaba.com> Signed-off-by: NJens Axboe <axboe@kernel.dk>
-
- 31 5月, 2018 2 次提交
-
-
由 Chengguang Xu 提交于
Change to return true/false only for bool type return code. Signed-off-by: NChengguang Xu <cgxu519@gmx.com> Signed-off-by: NJens Axboe <axboe@kernel.dk>
-
由 Liu Bo 提交于
tg in throtl_select_dispatch is used first and then do check. Since tg may be NULL, it has potential NULL pointer dereference risk. So fix it. Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com> Signed-off-by: NLiu Bo <bo.liu@linux.alibaba.com> Signed-off-by: NJens Axboe <axboe@kernel.dk>
-
- 09 5月, 2018 2 次提交
-
-
由 Omar Sandoval 提交于
struct blk_issue_stat squashes three things into one u64: - The time the driver started working on a request - The original size of the request (for the io.low controller) - Flags for writeback throttling It turns out that on x86_64, we have a 4 byte hole in struct request which we can fill with the non-timestamp fields from blk_issue_stat, simplifying things quite a bit. Signed-off-by: NOmar Sandoval <osandov@fb.com> Signed-off-by: NJens Axboe <axboe@kernel.dk>
-
由 Omar Sandoval 提交于
struct blk_issue_stat is going away, and bio->bi_issue_stat doesn't even use the blk-stats interface, so we can provide a separate implementation specific for bios. The helpers work the same way as the blk-stats helpers. Signed-off-by: NOmar Sandoval <osandov@fb.com> Signed-off-by: NJens Axboe <axboe@kernel.dk>
-
- 20 1月, 2018 1 次提交
-
-
由 weiping zhang 提交于
use queue_is_rq_based instead of open code. Signed-off-by: Nweiping zhang <zhangweiping@didichuxing.com> Signed-off-by: NJens Axboe <axboe@kernel.dk>
-
- 19 1月, 2018 2 次提交
-
-
由 Joseph Qi 提交于
In mixed read/write workload on SSD, write latency is much lower than read. But now we only track and record read latency and then use it as threshold base for both read and write io latency accounting. As a result, write io latency will always be considered as good and bad_bio_cnt is much smaller than 20% of bio_cnt. That is to mean, the tg to be checked will be treated as idle most of the time and still let others dispatch more ios, even it is truly running under low limit and wants its low limit to be guaranteed, which is not we expected in fact. So track read and write request individually, which can bring more precise latency control for low limit idle detection. Signed-off-by: NJoseph Qi <qijiang.qj@alibaba-inc.com> Reviewed-by: NShaohua Li <shli@fb.com> Signed-off-by: NJens Axboe <axboe@kernel.dk>
-
由 weiping zhang 提交于
export these two interface for cgroup-v1. Acked-by: NTejun Heo <tj@kernel.org> Signed-off-by: Nweiping zhang <zhangweiping@didichuxing.com> Signed-off-by: NJens Axboe <axboe@kernel.dk>
-
- 21 12月, 2017 1 次提交
-
-
由 Shaohua Li 提交于
If a bio is throttled and split after throttling, the bio could be resubmited and enters the throttling again. This will cause part of the bio to be charged multiple times. If the cgroup has an IO limit, the double charge will significantly harm the performance. The bio split becomes quite common after arbitrary bio size change. To fix this, we always set the BIO_THROTTLED flag if a bio is throttled. If the bio is cloned/split, we copy the flag to new bio too to avoid a double charge. However, cloned bio could be directed to a new disk, keeping the flag be a problem. The observation is we always set new disk for the bio in this case, so we can clear the flag in bio_set_dev(). This issue exists for a long time, arbitrary bio size change just makes it worse, so this should go into stable at least since v4.2. V1-> V2: Not add extra field in bio based on discussion with Tejun Cc: Vivek Goyal <vgoyal@redhat.com> Cc: stable@vger.kernel.org Acked-by: NTejun Heo <tj@kernel.org> Signed-off-by: NShaohua Li <shli@fb.com> Signed-off-by: NJens Axboe <axboe@kernel.dk>
-
- 22 11月, 2017 1 次提交
-
-
由 Kees Cook 提交于
This converts all remaining cases of the old setup_timer() API into using timer_setup(), where the callback argument is the structure already holding the struct timer_list. These should have no behavioral changes, since they just change which pointer is passed into the callback with the same available pointers after conversion. It handles the following examples, in addition to some other variations. Casting from unsigned long: void my_callback(unsigned long data) { struct something *ptr = (struct something *)data; ... } ... setup_timer(&ptr->my_timer, my_callback, ptr); and forced object casts: void my_callback(struct something *ptr) { ... } ... setup_timer(&ptr->my_timer, my_callback, (unsigned long)ptr); become: void my_callback(struct timer_list *t) { struct something *ptr = from_timer(ptr, t, my_timer); ... } ... timer_setup(&ptr->my_timer, my_callback, 0); Direct function assignments: void my_callback(unsigned long data) { struct something *ptr = (struct something *)data; ... } ... ptr->my_timer.function = my_callback; have a temporary cast added, along with converting the args: void my_callback(struct timer_list *t) { struct something *ptr = from_timer(ptr, t, my_timer); ... } ... ptr->my_timer.function = (TIMER_FUNC_TYPE)my_callback; And finally, callbacks without a data assignment: void my_callback(unsigned long data) { ... } ... setup_timer(&ptr->my_timer, my_callback, 0); have their argument renamed to verify they're unused during conversion: void my_callback(struct timer_list *unused) { ... } ... timer_setup(&ptr->my_timer, my_callback, 0); The conversion is done with the following Coccinelle script: spatch --very-quiet --all-includes --include-headers \ -I ./arch/x86/include -I ./arch/x86/include/generated \ -I ./include -I ./arch/x86/include/uapi \ -I ./arch/x86/include/generated/uapi -I ./include/uapi \ -I ./include/generated/uapi --include ./include/linux/kconfig.h \ --dir . \ --cocci-file ~/src/data/timer_setup.cocci @fix_address_of@ expression e; @@ setup_timer( -&(e) +&e , ...) // Update any raw setup_timer() usages that have a NULL callback, but // would otherwise match change_timer_function_usage, since the latter // will update all function assignments done in the face of a NULL // function initialization in setup_timer(). @change_timer_function_usage_NULL@ expression _E; identifier _timer; type _cast_data; @@ ( -setup_timer(&_E->_timer, NULL, _E); +timer_setup(&_E->_timer, NULL, 0); | -setup_timer(&_E->_timer, NULL, (_cast_data)_E); +timer_setup(&_E->_timer, NULL, 0); | -setup_timer(&_E._timer, NULL, &_E); +timer_setup(&_E._timer, NULL, 0); | -setup_timer(&_E._timer, NULL, (_cast_data)&_E); +timer_setup(&_E._timer, NULL, 0); ) @change_timer_function_usage@ expression _E; identifier _timer; struct timer_list _stl; identifier _callback; type _cast_func, _cast_data; @@ ( -setup_timer(&_E->_timer, _callback, _E); +timer_setup(&_E->_timer, _callback, 0); | -setup_timer(&_E->_timer, &_callback, _E); +timer_setup(&_E->_timer, _callback, 0); | -setup_timer(&_E->_timer, _callback, (_cast_data)_E); +timer_setup(&_E->_timer, _callback, 0); | -setup_timer(&_E->_timer, &_callback, (_cast_data)_E); +timer_setup(&_E->_timer, _callback, 0); | -setup_timer(&_E->_timer, (_cast_func)_callback, _E); +timer_setup(&_E->_timer, _callback, 0); | -setup_timer(&_E->_timer, (_cast_func)&_callback, _E); +timer_setup(&_E->_timer, _callback, 0); | -setup_timer(&_E->_timer, (_cast_func)_callback, (_cast_data)_E); +timer_setup(&_E->_timer, _callback, 0); | -setup_timer(&_E->_timer, (_cast_func)&_callback, (_cast_data)_E); +timer_setup(&_E->_timer, _callback, 0); | -setup_timer(&_E._timer, _callback, (_cast_data)_E); +timer_setup(&_E._timer, _callback, 0); | -setup_timer(&_E._timer, _callback, (_cast_data)&_E); +timer_setup(&_E._timer, _callback, 0); | -setup_timer(&_E._timer, &_callback, (_cast_data)_E); +timer_setup(&_E._timer, _callback, 0); | -setup_timer(&_E._timer, &_callback, (_cast_data)&_E); +timer_setup(&_E._timer, _callback, 0); | -setup_timer(&_E._timer, (_cast_func)_callback, (_cast_data)_E); +timer_setup(&_E._timer, _callback, 0); | -setup_timer(&_E._timer, (_cast_func)_callback, (_cast_data)&_E); +timer_setup(&_E._timer, _callback, 0); | -setup_timer(&_E._timer, (_cast_func)&_callback, (_cast_data)_E); +timer_setup(&_E._timer, _callback, 0); | -setup_timer(&_E._timer, (_cast_func)&_callback, (_cast_data)&_E); +timer_setup(&_E._timer, _callback, 0); | _E->_timer@_stl.function = _callback; | _E->_timer@_stl.function = &_callback; | _E->_timer@_stl.function = (_cast_func)_callback; | _E->_timer@_stl.function = (_cast_func)&_callback; | _E._timer@_stl.function = _callback; | _E._timer@_stl.function = &_callback; | _E._timer@_stl.function = (_cast_func)_callback; | _E._timer@_stl.function = (_cast_func)&_callback; ) // callback(unsigned long arg) @change_callback_handle_cast depends on change_timer_function_usage@ identifier change_timer_function_usage._callback; identifier change_timer_function_usage._timer; type _origtype; identifier _origarg; type _handletype; identifier _handle; @@ void _callback( -_origtype _origarg +struct timer_list *t ) { ( ... when != _origarg _handletype *_handle = -(_handletype *)_origarg; +from_timer(_handle, t, _timer); ... when != _origarg | ... when != _origarg _handletype *_handle = -(void *)_origarg; +from_timer(_handle, t, _timer); ... when != _origarg | ... when != _origarg _handletype *_handle; ... when != _handle _handle = -(_handletype *)_origarg; +from_timer(_handle, t, _timer); ... when != _origarg | ... when != _origarg _handletype *_handle; ... when != _handle _handle = -(void *)_origarg; +from_timer(_handle, t, _timer); ... when != _origarg ) } // callback(unsigned long arg) without existing variable @change_callback_handle_cast_no_arg depends on change_timer_function_usage && !change_callback_handle_cast@ identifier change_timer_function_usage._callback; identifier change_timer_function_usage._timer; type _origtype; identifier _origarg; type _handletype; @@ void _callback( -_origtype _origarg +struct timer_list *t ) { + _handletype *_origarg = from_timer(_origarg, t, _timer); + ... when != _origarg - (_handletype *)_origarg + _origarg ... when != _origarg } // Avoid already converted callbacks. @match_callback_converted depends on change_timer_function_usage && !change_callback_handle_cast && !change_callback_handle_cast_no_arg@ identifier change_timer_function_usage._callback; identifier t; @@ void _callback(struct timer_list *t) { ... } // callback(struct something *handle) @change_callback_handle_arg depends on change_timer_function_usage && !match_callback_converted && !change_callback_handle_cast && !change_callback_handle_cast_no_arg@ identifier change_timer_function_usage._callback; identifier change_timer_function_usage._timer; type _handletype; identifier _handle; @@ void _callback( -_handletype *_handle +struct timer_list *t ) { + _handletype *_handle = from_timer(_handle, t, _timer); ... } // If change_callback_handle_arg ran on an empty function, remove // the added handler. @unchange_callback_handle_arg depends on change_timer_function_usage && change_callback_handle_arg@ identifier change_timer_function_usage._callback; identifier change_timer_function_usage._timer; type _handletype; identifier _handle; identifier t; @@ void _callback(struct timer_list *t) { - _handletype *_handle = from_timer(_handle, t, _timer); } // We only want to refactor the setup_timer() data argument if we've found // the matching callback. This undoes changes in change_timer_function_usage. @unchange_timer_function_usage depends on change_timer_function_usage && !change_callback_handle_cast && !change_callback_handle_cast_no_arg && !change_callback_handle_arg@ expression change_timer_function_usage._E; identifier change_timer_function_usage._timer; identifier change_timer_function_usage._callback; type change_timer_function_usage._cast_data; @@ ( -timer_setup(&_E->_timer, _callback, 0); +setup_timer(&_E->_timer, _callback, (_cast_data)_E); | -timer_setup(&_E._timer, _callback, 0); +setup_timer(&_E._timer, _callback, (_cast_data)&_E); ) // If we fixed a callback from a .function assignment, fix the // assignment cast now. @change_timer_function_assignment depends on change_timer_function_usage && (change_callback_handle_cast || change_callback_handle_cast_no_arg || change_callback_handle_arg)@ expression change_timer_function_usage._E; identifier change_timer_function_usage._timer; identifier change_timer_function_usage._callback; type _cast_func; typedef TIMER_FUNC_TYPE; @@ ( _E->_timer.function = -_callback +(TIMER_FUNC_TYPE)_callback ; | _E->_timer.function = -&_callback +(TIMER_FUNC_TYPE)_callback ; | _E->_timer.function = -(_cast_func)_callback; +(TIMER_FUNC_TYPE)_callback ; | _E->_timer.function = -(_cast_func)&_callback +(TIMER_FUNC_TYPE)_callback ; | _E._timer.function = -_callback +(TIMER_FUNC_TYPE)_callback ; | _E._timer.function = -&_callback; +(TIMER_FUNC_TYPE)_callback ; | _E._timer.function = -(_cast_func)_callback +(TIMER_FUNC_TYPE)_callback ; | _E._timer.function = -(_cast_func)&_callback +(TIMER_FUNC_TYPE)_callback ; ) // Sometimes timer functions are called directly. Replace matched args. @change_timer_function_calls depends on change_timer_function_usage && (change_callback_handle_cast || change_callback_handle_cast_no_arg || change_callback_handle_arg)@ expression _E; identifier change_timer_function_usage._timer; identifier change_timer_function_usage._callback; type _cast_data; @@ _callback( ( -(_cast_data)_E +&_E->_timer | -(_cast_data)&_E +&_E._timer | -_E +&_E->_timer ) ) // If a timer has been configured without a data argument, it can be // converted without regard to the callback argument, since it is unused. @match_timer_function_unused_data@ expression _E; identifier _timer; identifier _callback; @@ ( -setup_timer(&_E->_timer, _callback, 0); +timer_setup(&_E->_timer, _callback, 0); | -setup_timer(&_E->_timer, _callback, 0L); +timer_setup(&_E->_timer, _callback, 0); | -setup_timer(&_E->_timer, _callback, 0UL); +timer_setup(&_E->_timer, _callback, 0); | -setup_timer(&_E._timer, _callback, 0); +timer_setup(&_E._timer, _callback, 0); | -setup_timer(&_E._timer, _callback, 0L); +timer_setup(&_E._timer, _callback, 0); | -setup_timer(&_E._timer, _callback, 0UL); +timer_setup(&_E._timer, _callback, 0); | -setup_timer(&_timer, _callback, 0); +timer_setup(&_timer, _callback, 0); | -setup_timer(&_timer, _callback, 0L); +timer_setup(&_timer, _callback, 0); | -setup_timer(&_timer, _callback, 0UL); +timer_setup(&_timer, _callback, 0); | -setup_timer(_timer, _callback, 0); +timer_setup(_timer, _callback, 0); | -setup_timer(_timer, _callback, 0L); +timer_setup(_timer, _callback, 0); | -setup_timer(_timer, _callback, 0UL); +timer_setup(_timer, _callback, 0); ) @change_callback_unused_data depends on match_timer_function_unused_data@ identifier match_timer_function_unused_data._callback; type _origtype; identifier _origarg; @@ void _callback( -_origtype _origarg +struct timer_list *unused ) { ... when != _origarg } Signed-off-by: NKees Cook <keescook@chromium.org>
-
- 02 11月, 2017 1 次提交
-
-
由 Greg Kroah-Hartman 提交于
Many source files in the tree are missing licensing information, which makes it harder for compliance tools to determine the correct license. By default all files without license information are under the default license of the kernel, which is GPL version 2. Update the files which contain no license information with the 'GPL-2.0' SPDX license identifier. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This patch is based on work done by Thomas Gleixner and Kate Stewart and Philippe Ombredanne. How this work was done: Patches were generated and checked against linux-4.14-rc6 for a subset of the use cases: - file had no licensing information it it. - file was a */uapi/* one with no licensing information in it, - file was a */uapi/* one with existing licensing information, Further patches will be generated in subsequent months to fix up cases where non-standard license headers were used, and references to license had to be inferred by heuristics based on keywords. The analysis to determine which SPDX License Identifier to be applied to a file was done in a spreadsheet of side by side results from of the output of two independent scanners (ScanCode & Windriver) producing SPDX tag:value files created by Philippe Ombredanne. Philippe prepared the base worksheet, and did an initial spot review of a few 1000 files. The 4.13 kernel was the starting point of the analysis with 60,537 files assessed. Kate Stewart did a file by file comparison of the scanner results in the spreadsheet to determine which SPDX license identifier(s) to be applied to the file. She confirmed any determination that was not immediately clear with lawyers working with the Linux Foundation. Criteria used to select files for SPDX license identifier tagging was: - Files considered eligible had to be source code files. - Make and config files were included as candidates if they contained >5 lines of source - File already had some variant of a license header in it (even if <5 lines). All documentation files were explicitly excluded. The following heuristics were used to determine which SPDX license identifiers to apply. - when both scanners couldn't find any license traces, file was considered to have no license information in it, and the top level COPYING file license applied. For non */uapi/* files that summary was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 11139 and resulted in the first patch in this series. If that file was a */uapi/* path one, it was "GPL-2.0 WITH Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 WITH Linux-syscall-note 930 and resulted in the second patch in this series. - if a file had some form of licensing information in it, and was one of the */uapi/* ones, it was denoted with the Linux-syscall-note if any GPL family license was found in the file or had no licensing in it (per prior point). Results summary: SPDX license identifier # files ---------------------------------------------------|------ GPL-2.0 WITH Linux-syscall-note 270 GPL-2.0+ WITH Linux-syscall-note 169 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17 LGPL-2.1+ WITH Linux-syscall-note 15 GPL-1.0+ WITH Linux-syscall-note 14 ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5 LGPL-2.0+ WITH Linux-syscall-note 4 LGPL-2.1 WITH Linux-syscall-note 3 ((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3 ((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1 and that resulted in the third patch in this series. - when the two scanners agreed on the detected license(s), that became the concluded license(s). - when there was disagreement between the two scanners (one detected a license but the other didn't, or they both detected different licenses) a manual inspection of the file occurred. - In most cases a manual inspection of the information in the file resulted in a clear resolution of the license that should apply (and which scanner probably needed to revisit its heuristics). - When it was not immediately clear, the license identifier was confirmed with lawyers working with the Linux Foundation. - If there was any question as to the appropriate license identifier, the file was flagged for further research and to be revisited later in time. In total, over 70 hours of logged manual review was done on the spreadsheet to determine the SPDX license identifiers to apply to the source files by Kate, Philippe, Thomas and, in some cases, confirmation by lawyers working with the Linux Foundation. Kate also obtained a third independent scan of the 4.13 code base from FOSSology, and compared selected files where the other two scanners disagreed against that SPDX file, to see if there was new insights. The Windriver scanner is based on an older version of FOSSology in part, so they are related. Thomas did random spot checks in about 500 files from the spreadsheets for the uapi headers and agreed with SPDX license identifier in the files he inspected. For the non-uapi files Thomas did random spot checks in about 15000 files. In initial set of patches against 4.14-rc6, 3 files were found to have copy/paste license identifier errors, and have been fixed to reflect the correct identifier. Additionally Philippe spent 10 hours this week doing a detailed manual inspection and review of the 12,461 patched files from the initial patch version early this week with: - a full scancode scan run, collecting the matched texts, detected license ids and scores - reviewing anything where there was a license detected (about 500+ files) to ensure that the applied SPDX license was correct - reviewing anything where there was no detection but the patch license was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied SPDX license was correct This produced a worksheet with 20 files needing minor correction. This worksheet was then exported into 3 different .csv files for the different types of files to be modified. These .csv files were then reviewed by Greg. Thomas wrote a script to parse the csv files and add the proper SPDX tag to the file, in the format that the file expected. This script was further refined by Greg based on the output to detect more types of files automatically and to distinguish between header and source .c files (which need different comment types.) Finally Greg ran the script using the .csv files to generate the patches. Reviewed-by: NKate Stewart <kstewart@linuxfoundation.org> Reviewed-by: NPhilippe Ombredanne <pombredanne@nexb.com> Reviewed-by: NThomas Gleixner <tglx@linutronix.de> Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
-
- 11 10月, 2017 1 次提交
-
-
由 Jiufei Xue 提交于
A null pointer dereference can occur when blkcg is removed manually with writeback IOs inflight. This is caused by the following case: Writeback kworker submit the bio and set bio->bi_cg_private to tg in blk_throtl_assoc_bio. Then we remove the block cgroup manually, the blkg and tg would be freed if there is no request inflight. When the submitted bio come back, blk_throtl_bio_endio() fetch the tg which was already freed. Fix this by increasing the refcount of blkg in funcion blk_throtl_assoc_bio() so that the blkg will not be freed until the bio_endio called. Reviewed-by: NShaohua Li <shli@fb.com> Signed-off-by: NJiufei Xue <jiufei.xjf@alibaba-inc.com> Signed-off-by: NJens Axboe <axboe@kernel.dk>
-
- 04 10月, 2017 1 次提交
-
-
由 Joseph Qi 提交于
There is a case which will lead to io stall. The case is described as follows. /test1 |-subtest1 /test2 |-subtest2 And subtest1 and subtest2 each has 32 queued bios already. Now upgrade to max. In throtl_upgrade_state, it will try to dispatch bios as follows: 1) tg=subtest1, do nothing; 2) tg=test1, transfer 32 queued bios from subtest1 to test1; no pending left, no need to schedule next dispatch; 3) tg=subtest2, do nothing; 4) tg=test2, transfer 32 queued bios from subtest2 to test2; no pending left, no need to schedule next dispatch; 5) tg=/, transfer 8 queued bios from test1 to /, 8 queued bios from test2 to /, 8 queued bios from test1 to /, and 8 queued bios from test2 to /; note that test1 and test2 each still has 16 queued bios left; 6) tg=/, try to schedule next dispatch, but since disptime is now (update in tg_update_disptime, wait=0), pending timer is not scheduled in fact; 7) In throtl_upgrade_state it totally dispatches 32 queued bios and with 32 left. test1 and test2 each has 16 queued bios; 8) throtl_pending_timer_fn sees the left over bios, but could do nothing, because throtl_select_dispatch returns 0, and test1/test2 has no pending tg. The blktrace shows the following: 8,32 0 0 2.539007641 0 m N throtl upgrade to max 8,32 0 0 2.539072267 0 m N throtl /test2 dispatch nr_queued=16 read=0 write=16 8,32 7 0 2.539077142 0 m N throtl /test1 dispatch nr_queued=16 read=0 write=16 So force schedule dispatch if there are pending children. Reviewed-by: NShaohua Li <shli@fb.com> Signed-off-by: NJoseph Qi <qijiang.qj@alibaba-inc.com> Signed-off-by: NJens Axboe <axboe@kernel.dk>
-
- 24 8月, 2017 1 次提交
-
-
由 Shaohua Li 提交于
discard request usually is very big and easily use all bandwidth budget of a cgroup. discard request size doesn't really mean the size of data written, so it doesn't make sense to account it into bandwidth budget. Jens pointed out treating the size 0 doesn't make sense too, because discard request does have cost. But it's not easy to find the actual cost. This patch simply makes the size one sector. Signed-off-by: NShaohua Li <shli@fb.com> Signed-off-by: NJens Axboe <axboe@kernel.dk>
-
- 29 7月, 2017 2 次提交
-
-
由 Shaohua Li 提交于
Currently cfq/bfq/blk-throttle output cgroup info in trace in their own way. Now we have standard blktrace API for this, so convert them to use it. Note, this changes the behavior a little bit. cgroup info isn't output by default, we only do this with 'blk_cgroup' option enabled. cgroup info isn't output as a string by default too, we only do this with 'blk_cgname' option enabled. Also cgroup info is output in different position of the note string. I think these behavior changes aren't a big issue (actually we make trace data shorter which is good), since the blktrace note is solely for debugging. Signed-off-by: NShaohua Li <shli@fb.com> Signed-off-by: NJens Axboe <axboe@kernel.dk>
-
由 Shaohua Li 提交于
blkcg_bio_issue_check() already gets blkcg for a BIO. bio_associate_blkcg() uses a percpu refcounter, so it's a very cheap operation. There is no point we don't attach the cgroup info into bio at blkcg_bio_issue_check. This also makes blktrace outputs correct cgroup info. Acked-by: NTejun Heo <tj@kernel.org> Signed-off-by: NShaohua Li <shli@fb.com> Signed-off-by: NJens Axboe <axboe@kernel.dk>
-
- 07 6月, 2017 2 次提交
-
-
由 Shaohua Li 提交于
hard disk IO latency varies a lot depending on spindle move. The latency range could be from several microseconds to several milliseconds. It's pretty hard to get the baseline latency used by io.low. We will use a different stragety here. The idea is only using IO with spindle move to determine if cgroup IO is in good state. For HD, if io latency is small (< 1ms), we ignore the IO. Such IO is likely from sequential IO, and is helpless to help determine if a cgroup's IO is impacted by other cgroups. With this, we only account IO with big latency. Then we can choose a hardcoded baseline latency for HD (4ms, which is typical IO latency with seek). With all these settings, the io.low latency works for both HD and SSD. Signed-off-by: NShaohua Li <shli@fb.com> Signed-off-by: NJens Axboe <axboe@fb.com>
-
由 Joseph Qi 提交于
I have encountered a NULL pointer dereference in throtl_schedule_pending_timer: [ 413.735396] BUG: unable to handle kernel NULL pointer dereference at 0000000000000038 [ 413.735535] IP: [<ffffffff812ebbbf>] throtl_schedule_pending_timer+0x3f/0x210 [ 413.735643] PGD 22c8cf067 PUD 22cb34067 PMD 0 [ 413.735713] Oops: 0000 [#1] SMP ...... This is caused by the following case: blk_throtl_bio throtl_schedule_next_dispatch <= sq is top level one without parent throtl_schedule_pending_timer sq_to_tg(sq)->td->throtl_slice <= sq_to_tg(sq) returns NULL Fix it by using sq_to_td instead of sq_to_tg(sq)->td, which will always return a valid td. Fixes: 297e3d85 ("blk-throttle: make throtl_slice tunable") Signed-off-by: NJoseph Qi <qijiang.qj@alibaba-inc.com> Reviewed-by: NShaohua Li <shli@fb.com> Signed-off-by: NJens Axboe <axboe@fb.com>
-
- 23 5月, 2017 4 次提交
-
-
由 Shaohua Li 提交于
Default value of io.low limit is 0. If user doesn't configure the limit, last patch makes cgroup be throttled to very tiny bps/iops, which could stall the system. A cgroup with default settings of io.low limit really means nothing, so we force user to configure all settings, otherwise io.low limit doesn't take effect. With this stragety, default setting of latency/idle isn't important, so just set them to very conservative and safe value. Signed-off-by: NShaohua Li <shli@fb.com> Acked-by: NTejun Heo <tj@kernel.org> Signed-off-by: NJens Axboe <axboe@fb.com>
-
由 Shaohua Li 提交于
If a cgroup with low limit 0 for both bps/iops, the cgroup's low limit is ignored and we throttle the cgroup with its max limit. In this way, other cgroups with a low limit will not get protected. To fix this, we don't do the exception any more. cgroup will be throttled to a limit 0 if it uese default setting. To avoid completed stall, we give such cgroup tiny IO resources. Signed-off-by: NShaohua Li <shli@fb.com> Acked-by: NTejun Heo <tj@kernel.org> Signed-off-by: NJens Axboe <axboe@fb.com>
-
由 Shaohua Li 提交于
These info are important to understand what's happening and help debug. Signed-off-by: NShaohua Li <shli@fb.com> Acked-by: NTejun Heo <tj@kernel.org> Signed-off-by: NJens Axboe <axboe@fb.com>
-
由 Shaohua Li 提交于
For idle time, children's setting should not be bigger than parent's. For latency target, children's setting should not be smaller than parent's. The leaf nodes will adjust their settings according to the hierarchy and compare their IO with the settings and do upgrade/downgrade. parents nodes don't need to track their IO latency/idle time. Signed-off-by: NShaohua Li <shli@fb.com> Acked-by: NTejun Heo <tj@kernel.org> Signed-off-by: NJens Axboe <axboe@fb.com>
-
- 20 4月, 2017 1 次提交
-
-
由 Jens Axboe 提交于
We trigger this warning: block/blk-throttle.c: In function ‘blk_throtl_bio’: block/blk-throttle.c:2042:6: warning: variable ‘ret’ set but not used [-Wunused-but-set-variable] int ret; ^~~ since we only assign 'ret' if BLK_DEV_THROTTLING_LOW is off, we never check it. Reported-by: NBart Van Assche <bart.vanassche@sandisk.com> Reviewed-by: NBart Van Assche <bart.vanassche@sandisk.com> Signed-off-by: NJens Axboe <axboe@fb.com>
-
- 28 3月, 2017 8 次提交
-
-
由 Shaohua Li 提交于
One hard problem adding .low limit is to detect idle cgroup. If one cgroup doesn't dispatch enough IO against its low limit, we must have a mechanism to determine if other cgroups dispatch more IO. We added the think time detection mechanism before, but it doesn't work for all workloads. Here we add a latency based approach. We already have mechanism to calculate latency threshold for each IO size. For every IO dispatched from a cgorup, we compare its latency against its threshold and record the info. If most IO latency is below threshold (in the code I use 75%), the cgroup could be treated idle and other cgroups can dispatch more IO. Currently this latency target check is only for SSD as we can't calcualte the latency target for hard disk. And this is only for cgroup leaf node so far. Signed-off-by: NShaohua Li <shli@fb.com> Signed-off-by: NJens Axboe <axboe@fb.com>
-
由 Shaohua Li 提交于
User configures latency target, but the latency threshold for each request size isn't fixed. For a SSD, the IO latency highly depends on request size. To calculate latency threshold, we sample some data, eg, average latency for request size 4k, 8k, 16k, 32k .. 1M. The latency threshold of each request size will be the sample latency (I'll call it base latency) plus latency target. For example, the base latency for request size 4k is 80us and user configures latency target 60us. The 4k latency threshold will be 80 + 60 = 140us. To sample data, we calculate the order base 2 of rounded up IO sectors. If the IO size is bigger than 1M, it will be accounted as 1M. Since the calculation does round up, the base latency will be slightly smaller than actual value. Also if there isn't any IO dispatched for a specific IO size, we will use the base latency of smaller IO size for this IO size. But we shouldn't sample data at any time. The base latency is supposed to be latency where disk isn't congested, because we use latency threshold to schedule IOs between cgroups. If disk is congested, the latency is higher, using it for scheduling is meaningless. Hence we only do the sampling when block throttling is in the LOW limit, with assumption disk isn't congested in such state. If the assumption isn't true, eg, low limit is too high, calculated latency threshold will be higher. Hard disk is completely different. Latency depends on spindle seek instead of request size. Currently this feature is SSD only, we probably can use a fixed threshold like 4ms for hard disk though. Signed-off-by: NShaohua Li <shli@fb.com> Signed-off-by: NJens Axboe <axboe@fb.com>
-
由 Shaohua Li 提交于
Here we introduce per-cgroup latency target. The target determines how a cgroup can afford latency increasement. We will use the target latency to calculate a threshold and use it to schedule IO for cgroups. If a cgroup's bandwidth is below its low limit but its average latency is below the threshold, other cgroups can safely dispatch more IO even their bandwidth is higher than their low limits. On the other hand, if the first cgroup's latency is higher than the threshold, other cgroups are throttled to their low limits. So the target latency determines how we efficiently utilize free disk resource without sacifice of worload's IO latency. For example, assume 4k IO average latency is 50us when disk isn't congested. A cgroup sets the target latency to 30us. Then the cgroup can accept 50+30=80us IO latency. If the cgroupt's average IO latency is 90us and its bandwidth is below low limit, other cgroups are throttled to their low limit. If the cgroup's average IO latency is 60us, other cgroups are allowed to dispatch more IO. When other cgroups dispatch more IO, the first cgroup's IO latency will increase. If it increases to 81us, we then throttle other cgroups. User will configure the interface in this way: echo "8:16 rbps=2097152 wbps=max latency=100 idle=200" > io.low latency is in microsecond unit By default, latency target is 0, which means to guarantee IO latency. Signed-off-by: NShaohua Li <shli@fb.com> Signed-off-by: NJens Axboe <axboe@fb.com>
-
由 Shaohua Li 提交于
Last patch introduces a way to detect idle cgroup. We use it to make upgrade/downgrade decision. And the new algorithm can detect completely idle cgroup too, so we can delete the corresponding code. Signed-off-by: NShaohua Li <shli@fb.com> Signed-off-by: NJens Axboe <axboe@fb.com>
-
由 Shaohua Li 提交于
Add interface to configure the threshold. The io.low interface will like: echo "8:16 rbps=2097152 wbps=max idle=2000" > io.low idle is in microsecond unit. Signed-off-by: NShaohua Li <shli@fb.com> Signed-off-by: NJens Axboe <axboe@fb.com>
-
由 Shaohua Li 提交于
A cgroup gets assigned a low limit, but the cgroup could never dispatch enough IO to cross the low limit. In such case, the queue state machine will remain in LIMIT_LOW state and all other cgroups will be throttled according to low limit. This is unfair for other cgroups. We should treat the cgroup idle and upgrade the state machine to lower state. We also have a downgrade logic. If the state machine upgrades because of cgroup idle (real idle), the state machine will downgrade soon as the cgroup is below its low limit. This isn't what we want. A more complicated case is cgroup isn't idle when queue is in LIMIT_LOW. But when queue gets upgraded to lower state, other cgroups could dispatch more IO and this cgroup can't dispatch enough IO, so the cgroup is below its low limit and looks like idle (fake idle). In this case, the queue should downgrade soon. The key to determine if we should do downgrade is to detect if cgroup is truely idle. Unfortunately it's very hard to determine if a cgroup is real idle. This patch uses the 'think time check' idea from CFQ for the purpose. Please note, the idea doesn't work for all workloads. For example, a workload with io depth 8 has disk utilization 100%, hence think time is 0, eg, not idle. But the workload can run higher bandwidth with io depth 16. Compared to io depth 16, the io depth 8 workload is idle. We use the idea to roughly determine if a cgroup is idle. We treat a cgroup idle if its think time is above a threshold (by default 1ms for SSD and 100ms for HD). The idea is think time above the threshold will start to harm performance. HD is much slower so a longer think time is ok. The patch (and the latter patches) uses 'unsigned long' to track time. We convert 'ns' to 'us' with 'ns >> 10'. This is fast but loses precision, should not a big deal. Signed-off-by: NShaohua Li <shli@fb.com> Signed-off-by: NJens Axboe <axboe@fb.com>
-
由 Shaohua Li 提交于
When cgroups all reach low limit, cgroups can dispatch more IO. This could make some cgroups dispatch more IO but others not, and even some cgroups could dispatch less IO than their low limit. For example, cg1 low limit 10MB/s, cg2 limit 80MB/s, assume disk maximum bandwidth is 120M/s for the workload. Their bps could something like this: cg1/cg2 bps: T1: 10/80 -> T2: 60/60 -> T3: 10/80 At T1, all cgroups reach low limit, so they can dispatch more IO later. Then cg1 dispatch more IO and cg2 has no room to dispatch enough IO. At T2, cg2 only dispatches 60M/s. Since We detect cg2 dispatches less IO than its low limit 80M/s, we downgrade the queue from LIMIT_MAX to LIMIT_LOW, then all cgroups are throttled to their low limit (T3). cg2 will have bandwidth below its low limit at most time. The big problem here is we don't know the maximum bandwidth of the workload, so we can't make smart decision to avoid the situation. This patch makes cgroup bandwidth change smooth. After disk upgrades from LIMIT_LOW to LIMIT_MAX, we don't allow cgroups use all bandwidth upto their max limit immediately. Their bandwidth limit will be increased gradually to avoid above situation. So above example will became something like: cg1/cg2 bps: 10/80 -> 15/105 -> 20/100 -> 25/95 -> 30/90 -> 35/85 -> 40/80 -> 45/75 -> 22/98 In this way cgroups bandwidth will be above their limit in majority time, this still doesn't fully utilize disk bandwidth, but that's something we pay for sharing. Scale up is linear. The limit scales up 1/2 .low limit every throtl_slice after upgrade. The scale up will stop if the adjusted limit hits .max limit. Scale down is exponential. We cut the scale value half if a cgroup doesn't hit its .low limit. If the scale becomes 0, we then fully downgrade the queue to LIMIT_LOW state. Note this doesn't completely avoid cgroup running under its low limit. The best way to guarantee cgroup doesn't run under its limit is to set max limit. For example, if we set cg1 max limit to 40, cg2 will never run under its low limit. Signed-off-by: NShaohua Li <shli@fb.com> Signed-off-by: NJens Axboe <axboe@fb.com>
-
由 Shaohua Li 提交于
cgroup could be assigned a limit, but doesn't dispatch enough IO, eg the cgroup is idle. When this happens, the cgroup doesn't hit its limit, so we can't move the state machine to higher level and all cgroups will be throttled to their lower limit, so we waste bandwidth. Detecting idle cgroup is hard. This patch handles a simple case, a cgroup doesn't dispatch any IO. We ignore such cgroup's limit, so other cgroups can use the bandwidth. Please note this will be replaced with a more sophisticated algorithm later, but this demonstrates the idea how we handle idle cgroups, so I leave it here. Signed-off-by: NShaohua Li <shli@fb.com> Signed-off-by: NJens Axboe <axboe@fb.com>
-