throtl_slice is now a constant. Remove the variable and use the constant
directly where needed.
Cc: Yu Kuai <yukuai@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Khazhismel Kumykov <khazhy@google.com>
Reviewed-by: Yu Kuai <yukuai@fnnas.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
After the removal of CONFIG_BLK_DEV_THROTTLING_LOW, it is no longer
necessary to enable block accounting, so remove the call to
blk_stat_enable_accounting(). With that, the track_bio_latency variable
is no longer used and can be deleted from struct throtl_data. Also,
including blk-stat.h is no longer necessary.
Fixes: bf20ab538c ("blk-throttle: remove CONFIG_BLK_DEV_THROTTLING_LOW")
Cc: Yu Kuai <yukuai@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Khazhismel Kumykov <khazhy@google.com>
Reviewed-by: Yu Kuai <yukuai@fnnas.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Commit d61fcfa4bb ("blk-throttle: choose a small throtl_slice for SSD")
introduced device type specific throttle slices if BLK_DEV_THROTTLING_LOW
was enabled. Commit bf20ab538c ("blk-throttle: remove
CONFIG_BLK_DEV_THROTTLING_LOW") removed support for BLK_DEV_THROTTLING_LOW,
but left the device type specific throttle slices in place. This
effectively changed throttling behavior on systems with SSD which now use
a different and non-configurable slice time compared to non-SSD devices.
Practical impact is that throughput tests with low configured throttle
values (65536 bps) experience less than expected throughput on SSDs,
presumably due to rounding errors associated with the small throttle slice
time used for those devices. The same tests pass when setting the throttle
values to 65536 * 4 = 262144 bps.
The original code sets the throttle slice time to DFL_THROTL_SLICE_HD if
CONFIG_BLK_DEV_THROTTLING_LOW is disabled. Restore that code to fix the
problem. With that, DFL_THROTL_SLICE_SSD is no longer necessary. Revert to
the original code and re-introduce DFL_THROTL_SLICE to replace both
DFL_THROTL_SLICE_HD and DFL_THROTL_SLICE_SSD. This effectively reverts
commit d61fcfa4bb ("blk-throttle: choose a small throtl_slice for SSD").
While at it, also remove MAX_THROTL_SLICE since it is not used anymore.
Fixes: bf20ab538c ("blk-throttle: remove CONFIG_BLK_DEV_THROTTLING_LOW")
Cc: Yu Kuai <yukuai@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Khazhismel Kumykov <khazhy@google.com>
Reviewed-by: Yu Kuai <yukuai@fnnas.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Tightening the throttle activation check in blk_throtl_activated() to
require both q->td presence and policy bit set introduced a memory leak
during disk release:
blkg_destroy_all() clears the policy bit first during queue deactivation,
causing subsequent blk_throtl_exit() to skip throtl_data cleanup when
blk_throtl_activated() fails policy check.
Idealy we should avoid modifying blk_throtl_exit() activation check because
it's intuitive that blk-throtl start from blk_throtl_init() and end in
blk_throtl_exit(). However, call blk_throtl_exit() before
blkg_destroy_all() will make a long term deadlock problem easier to
trigger[1], hence fix this problem by checking if q->td is NULL from
blk_throtl_exit(), and remove policy deactivation as well since it's
useless.
[1] https://lore.kernel.org/all/CAHj4cs9p9H5yx+ywsb3CMUdbqGPhM+8tuBvhW=9ADiCjAqza9w@mail.gmail.com/#t
Fixes: bd9fd5be6b ("blk-throttle: fix access race during throttle policy activation")
Reported-by: Yi Zhang <yi.zhang@redhat.com>
Closes: https://lore.kernel.org/all/CAHj4cs-p-ZwBEKigBj7T6hQCOo-H68-kVwCrV6ZvRovrr9Z+HA@mail.gmail.com/
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Currently, split bio will be chained to original bio, and original bio
will be resubmitted to the tail of current->bio_list, waiting for
split bio to be issued. However, if split bio get split again, the IO
order will be messed up. This problem, on the one hand, will cause
performance degradation, especially for mdraid with large IO size; on
the other hand, will cause write errors for zoned block devices[1].
For example, in raid456 IO will first be split by max_sector from
md_submit_bio(), and then later be split again by chunksize for internal
handling:
For example, assume max_sectors is 1M, and chunksize is 512k
1) issue a 2M IO:
bio issuing: 0+2M
current->bio_list: NULL
2) md_submit_bio() split by max_sector:
bio issuing: 0+1M
current->bio_list: 1M+1M
3) chunk_aligned_read() split by chunksize:
bio issuing: 0+512k
current->bio_list: 1M+1M -> 512k+512k
4) after first bio issued, __submit_bio_noacct() will contuine issuing
next bio:
bio issuing: 1M+1M
current->bio_list: 512k+512k
bio issued: 0+512k
5) chunk_aligned_read() split by chunksize:
bio issuing: 1M+512k
current->bio_list: 512k+512k -> 1536k+512k
bio issued: 0+512k
6) no split afterwards, finally the issue order is:
0+512k -> 1M+512k -> 512k+512k -> 1536k+512k
This behaviour will cause large IO read on raid456 endup to be small
discontinuous IO in underlying disks. Fix this problem by placing split
bio to the head of current->bio_list.
Test script: test on 8 disk raid5 with 64k chunksize
dd if=/dev/md0 of=/dev/null bs=4480k iflag=direct
Test results:
Before this patch
1) iostat results:
Device r/s rMB/s rrqm/s %rrqm r_await rareq-sz aqu-sz %util
md0 52430.00 3276.87 0.00 0.00 0.62 64.00 32.60 80.10
sd* 4487.00 409.00 2054.00 31.40 0.82 93.34 3.68 71.20
2) blktrace G stage:
8,0 0 486445 11.357392936 843 G R 14071424 + 128 [dd]
8,0 0 486451 11.357466360 843 G R 14071168 + 128 [dd]
8,0 0 486454 11.357515868 843 G R 14071296 + 128 [dd]
8,0 0 486468 11.357968099 843 G R 14072192 + 128 [dd]
8,0 0 486474 11.358031320 843 G R 14071936 + 128 [dd]
8,0 0 486480 11.358096298 843 G R 14071552 + 128 [dd]
8,0 0 486490 11.358303858 843 G R 14071808 + 128 [dd]
3) io seek for sdx:
Noted io seek is the result from blktrace D stage, statistic of:
ABS((offset of next IO) - (offset + len of previous IO))
Read|Write seek
cnt 55175, zero cnt 25079
>=(KB) .. <(KB) : count ratio |distribution |
0 .. 1 : 25079 45.5% |########################################|
1 .. 2 : 0 0.0% | |
2 .. 4 : 0 0.0% | |
4 .. 8 : 0 0.0% | |
8 .. 16 : 0 0.0% | |
16 .. 32 : 0 0.0% | |
32 .. 64 : 12540 22.7% |##################### |
64 .. 128 : 2508 4.5% |##### |
128 .. 256 : 0 0.0% | |
256 .. 512 : 10032 18.2% |################# |
512 .. 1024 : 5016 9.1% |######### |
After this patch:
1) iostat results:
Device r/s rMB/s rrqm/s %rrqm r_await rareq-sz aqu-sz %util
md0 87965.00 5271.88 0.00 0.00 0.16 61.37 14.03 90.60
sd* 6020.00 658.44 5117.00 45.95 0.44 112.00 2.68 86.50
2) blktrace G stage:
8,0 0 206296 5.354894072 664 G R 7156992 + 128 [dd]
8,0 0 206305 5.355018179 664 G R 7157248 + 128 [dd]
8,0 0 206316 5.355204438 664 G R 7157504 + 128 [dd]
8,0 0 206319 5.355241048 664 G R 7157760 + 128 [dd]
8,0 0 206333 5.355500923 664 G R 7158016 + 128 [dd]
8,0 0 206344 5.355837806 664 G R 7158272 + 128 [dd]
8,0 0 206353 5.355960395 664 G R 7158528 + 128 [dd]
8,0 0 206357 5.356020772 664 G R 7158784 + 128 [dd]
3) io seek for sdx
Read|Write seek
cnt 28644, zero cnt 21483
>=(KB) .. <(KB) : count ratio |distribution |
0 .. 1 : 21483 75.0% |########################################|
1 .. 2 : 0 0.0% | |
2 .. 4 : 0 0.0% | |
4 .. 8 : 0 0.0% | |
8 .. 16 : 0 0.0% | |
16 .. 32 : 0 0.0% | |
32 .. 64 : 7161 25.0% |############## |
BTW, this looks like a long term problem from day one, and large
sequential IO read is pretty common case like video playing.
And even with this patch, in this test case IO is merged to at most 128k
is due to block layer plug limit BLK_PLUG_FLUSH_SIZE, increase such
limit can get even better performance. However, we'll figure out how to do
this properly later.
[1] https://lore.kernel.org/all/e40b076d-583d-406b-b223-005910a9f46f@acm.org/
Fixes: d89d87965d ("When stacked block devices are in-use (e.g. md or dm), the recursive calls")
Reported-by: Tie Ren <tieren@fnnas.com>
Closes: https://lore.kernel.org/all/7dro5o7u5t64d6bgiansesjavxcuvkq5p2pok7dtwkav7b7ape@3isfr44b6352/
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
On repeated cold boots we occasionally hit a NULL pointer crash in
blk_should_throtl() when throttling is consulted before the throttle
policy is fully enabled for the queue. Checking only q->td != NULL is
insufficient during early initialization, so blkg_to_pd() for the
throttle policy can still return NULL and blkg_to_tg() becomes NULL,
which later gets dereferenced.
Unable to handle kernel NULL pointer dereference
at virtual address 0000000000000156
...
pc : submit_bio_noacct+0x14c/0x4c8
lr : submit_bio_noacct+0x48/0x4c8
sp : ffff800087f0b690
x29: ffff800087f0b690 x28: 0000000000005f90 x27: ffff00068af393c0
x26: 0000000000080000 x25: 000000000002fbc0 x24: ffff000684ddcc70
x23: 0000000000000000 x22: 0000000000000000 x21: 0000000000000000
x20: 0000000000080000 x19: ffff000684ddcd08 x18: ffffffffffffffff
x17: 0000000000000000 x16: ffff80008132a550 x15: 0000ffff98020fff
x14: 0000000000000000 x13: 1fffe000d11d7021 x12: ffff000688eb810c
x11: ffff00077ec4bb80 x10: ffff000688dcb720 x9 : ffff80008068ef60
x8 : 00000a6fb8a86e85 x7 : 000000000000111e x6 : 0000000000000002
x5 : 0000000000000246 x4 : 0000000000015cff x3 : 0000000000394500
x2 : ffff000682e35e40 x1 : 0000000000364940 x0 : 000000000000001a
Call trace:
submit_bio_noacct+0x14c/0x4c8
verity_map+0x178/0x2c8
__map_bio+0x228/0x250
dm_submit_bio+0x1c4/0x678
__submit_bio+0x170/0x230
submit_bio_noacct_nocheck+0x16c/0x388
submit_bio_noacct+0x16c/0x4c8
submit_bio+0xb4/0x210
f2fs_submit_read_bio+0x4c/0xf0
f2fs_mpage_readpages+0x3b0/0x5f0
f2fs_readahead+0x90/0xe8
Tighten blk_throtl_activated() to also require that the throttle policy
bit is set on the queue:
return q->td != NULL &&
test_bit(blkcg_policy_throtl.plid, q->blkcg_pols);
This prevents blk_should_throtl() from accessing throttle group state
until policy data has been attached to blkgs.
Fixes: a3166c5170 ("blk-throttle: delay initialization until configuration")
Co-developed-by: Liang Jie <liangjie@lixiang.com>
Signed-off-by: Liang Jie <liangjie@lixiang.com>
Signed-off-by: Han Guangjiang <hanguangjiang@lixiang.com>
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Move this API to the canonical timer_*() namespace.
[ tglx: Redone against pre rc1 ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/aB2X0jCKQO56WdMt@gmail.com
If blk-throttle is enabled but blktrace is not, then the compiler will
notice that the following two variables are unused:
../block/blk-throttle.c: In function 'throtl_pending_timer_fn':
../block/blk-throttle.c:1153:30: warning: unused variable 'bio_cnt_w' [-Wunused-variable]
1153 | unsigned int bio_cnt_w = sq_queued(sq, WRITE);
| ^~~~~~~~~
../block/blk-throttle.c:1152:30: warning: unused variable 'bio_cnt_r' [-Wunused-variable]
1152 | unsigned int bio_cnt_r = sq_queued(sq, READ);
| ^~~~~~~~~
Silence that my annotating them with __maybe_unused.
Fixes: 28ad83b774 ("blk-throttle: Split the service queue")
Link: https://lore.kernel.org/all/20250515130830.9671-1-aishwarya.tcv@arm.com/
Reported-by: Aishwarya <aishwarya.tcv@arm.com>
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
[BUG]
There has an issue of io delayed dispatch caused by io splitting. Consider
the following scenario:
1) If we set a BPS limit of 1MB/s and restrict the maximum IO size per
dispatch to 4KB, submitting -two- 1MB IO requests results in completion
times of 1s and 2s, which is expected.
2) However, if we additionally set an IOPS limit of 1,000,000/s with the
same BPS limit of 1MB/s, submitting -two- 1MB IO requests again results in
both completing in 2s, even though the IOPS constraint is being met.
[CAUSE]
This issue arises because BPS and IOPS currently share the same queue in
the blkthrotl mechanism:
1) This issue does not occur when only BPS is limited because the split IOs
return false in blk_should_throtl() and do not go through to throtl again.
2) For split IOs, even if they have been tagged with BIO_BPS_THROTTLED,
they still get queued alternately in the same list due to continuous
splitting and reordering. As a result, the two IO requests are both
completed at the 2-second mark, causing an unintended delay.
3) It is not difficult to imagine that in this scenario, if N 1MB IOs are
issued at once, all IOs will eventually complete together in N seconds.
[FIX]
With the queue separation introduced in the previous patches, we now have
separate BPS and IOPS queues. For IOs that have already passed the BPS
limitation, they do not need to re-enter the BPS queue and can directly
placed to the IOPS queue.
Since we have split the queues, when the IOPS queue is previously empty
and a new bio is added to the first qnode->bios_iops list in the
service_queue, we also need to update the disptime. This patch introduces
"THROTL_TG_IOPS_WAS_EMPTY" flag to mark it.
Signed-off-by: Zizhi Wo <wozizhi@huawei.com>
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Zizhi Wo <wozizhi@huaweicloud.com>
Link: https://lore.kernel.org/r/20250506020935.655574-8-wozizhi@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This patch splits throtl_service_queue->nr_queued into "nr_queued_bps" and
"nr_queued_iops", allowing separate accounting of BPS and IOPS queued bios.
This prepares for future changes that need to check whether the BPS or IOPS
queues are empty.
To facilitate updating the number of IOs in the BPS and IOPS queues, the
addition logic will be moved from throtl_add_bio_tg() to
throtl_qnode_add_bio(), and similarly, the removal logic will be moved from
tg_dispatch_one_bio() to throtl_pop_queued().
And introduce sq_queued() to calculate the total sum of sq->nr_queued.
Signed-off-by: Zizhi Wo <wozizhi@huawei.com>
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Zizhi Wo <wozizhi@huaweicloud.com>
Link: https://lore.kernel.org/r/20250506020935.655574-7-wozizhi@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This patch splits the single queue into separate bps and iops queues. Now,
an IO request must first pass through the bps queue, then the iops queue,
and finally be dispatched. Due to the queue splitting, we need to modify
the throtl add/peek/pop function.
Additionally, the patch modifies the logic related to tg_dispatch_time().
If bio needs to wait for bps, function directly returns the bps wait time;
otherwise, it charges bps and returns the iops wait time so that bio can be
directly placed into the iops queue afterward. Note that this may lead to
more frequent updates to disptime, but the overhead is negligible for the
slow path.
Signed-off-by: Zizhi Wo <wozizhi@huawei.com>
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Zizhi Wo <wozizhi@huaweicloud.com>
Link: https://lore.kernel.org/r/20250506020935.655574-6-wozizhi@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Subsequent patches will split the single queue into separate bps and iops
queues. To prevent IO that has already passed through the bps queue at a
single tg level from being counted toward bps wait time again, we introduce
"BIO_TG_BPS_THROTTLED" flag. Since throttle and QoS operate at different
levels, we reuse the value as "BIO_QOS_THROTTLED".
We set this flag when charge bps and clear it when charge iops, as the bio
will move to the upper-level tg or be dispatched.
This patch does not involve functional changes.
Signed-off-by: Zizhi Wo <wozizhi@huawei.com>
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Zizhi Wo <wozizhi@huaweicloud.com>
Link: https://lore.kernel.org/r/20250506020935.655574-5-wozizhi@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Split throtl_charge_bio() to facilitate subsequent patches that will
separately charge bps and iops after queue separation.
Signed-off-by: Zizhi Wo <wozizhi@huawei.com>
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Zizhi Wo <wozizhi@huaweicloud.com>
Link: https://lore.kernel.org/r/20250506020935.655574-4-wozizhi@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
tg_dispatch_time() contained both bps and iops throttling logic. We now
split its internal logic into tg_dispatch_bps/iops_time() to improve code
consistency for future separation of the bps and iops queues.
Besides, merge time_before() from caller into throtl_extend_slice() to make
code cleaner.
Signed-off-by: Zizhi Wo <wozizhi@huawei.com>
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Zizhi Wo <wozizhi@huaweicloud.com>
Link: https://lore.kernel.org/r/20250506020935.655574-3-wozizhi@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
tg_may_dispatch() can directly indicate whether bio can be dispatched by
returning the time to wait, without the need for the redundant "wait"
parameter. Remove it and modify the function's return type accordingly.
Since we have determined by the return time whether bio can be dispatched,
rename tg_may_dispatch() to tg_dispatch_time().
Signed-off-by: Zizhi Wo <wozizhi@huawei.com>
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Zizhi Wo <wozizhi@huaweicloud.com>
Link: https://lore.kernel.org/r/20250506020935.655574-2-wozizhi@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Now the tg->[bytes/io]_disp type is signed, and calculate_bytes/io_allowed
return type is unsigned. Even if the bps/iops limit is not set to max, the
return value of the function may still exceed INT_MAX or LLONG_MAX, which
can cause overflow in outer variables. In such cases, we can add additional
checks accordingly.
And in throtl_trim_slice(), if the BPS/IOPS limit is set to max, there's
no need to call calculate_bytes/io_allowed(). Introduces the helper
functions throtl_trim_bps/iops to simplifies the process. For cases when
the calculated trim value exceeds INT_MAX (causing an overflow), we reset
tg->[bytes/io]_disp to zero, so return original tg->[bytes/io]_disp because
it is the size that is actually trimmed.
Signed-off-by: Zizhi Wo <wozizhi@huawei.com>
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Link: https://lore.kernel.org/r/20250417132054.2866409-4-wozizhi@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
We no longer need carryover_[bytes/ios] in tg, so it is removed. The
related comments about carryover in tg are also merged into
[bytes/io]_disp, and modify other related comments.
Signed-off-by: Zizhi Wo <wozizhi@huawei.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Link: https://lore.kernel.org/r/20250417132054.2866409-3-wozizhi@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
In commit 6cc477c368 ("blk-throttle: carry over directly"), the carryover
bytes/ios was be carried to [bytes/io]_disp. However, its update mechanism
has some issues.
In __tg_update_carryover(), we calculate "bytes" and "ios" to represent the
carryover, but the computation when updating [bytes/io]_disp is incorrect.
And if the sq->nr_queued is empty, we may not update tg->[bytes/io]_disp to
0 in tg_update_carryover(). We should set it to 0 in non carryover case.
This patch fixes the issue.
Fixes: 6cc477c368 ("blk-throttle: carry over directly")
Signed-off-by: Zizhi Wo <wozizhi@huawei.com>
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20250417132054.2866409-2-wozizhi@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
timer_delete[_sync]() replaces del_timer[_sync](). Convert the whole tree
over and remove the historical wrapper inlines.
Conversion was done with coccinelle plus manual fixups where necessary.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Now ->carryover_bytes[] and ->carryover_ios[] only covers limit/config
update.
Actually the carryover bytes/ios can be carried to ->bytes_disp[] and
->io_disp[] directly, since the carryover is one-shot thing and only valid
in current slice.
Then we can remove the two fields and simplify code much.
Type of ->bytes_disp[] and ->io_disp[] has to change as signed because the
two fields may become negative when updating limits or config, but both are
big enough for holding bytes/ios dispatched in single slice
Cc: Tejun Heo <tj@kernel.org>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20250305043123.3938491-4-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Commit 29390bb566 ("blk-throttle: support prioritized processing of metadata")
takes bytes/ios carryover for prioritized processing of metadata. Turns out
we can support it by charging it directly without trimming slice, and the
result is same with carryover.
Cc: Tejun Heo <tj@kernel.org>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20250305043123.3938491-3-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The two fields are not used any more, so remove them.
Cc: Tejun Heo <tj@kernel.org>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20250305043123.3938491-2-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The bio submission time may be a few jiffies more than the expected
waiting time, due to 'extra_bytes' can't be divided in
tg_within_bps_limit(), and also due to timer wakeup delay.
In this case, adjust slice_start to jiffies will discard the extra wait time,
causing lower rate than expected.
Current in-tree code already covers deviation by rounddown(), but turns
out it is not enough, because jiffies - slice_start can be a multiple of
throtl_slice.
For example, assume bps_limit is 1000bytes, 1 jiffes is 10ms, and
slice is 20ms(2 jiffies), expected rate is 1000 / 1000 * 20 = 20 bytes
per slice.
If user issues two 21 bytes IO, then wait time will be 30ms for the
first IO:
bytes_allowed = 20, extra_bytes = 1;
jiffy_wait = 1 + 2 = 3 jiffies
and consider
extra 1 jiffies by timer, throtl_trim_slice() will be called at:
jiffies = 40ms
slice_start = 0ms, slice_end= 40ms
bytes_disp = 21
In this case, before the patch, real rate in the first two slices is
10.5 bytes per slice, and slice will be updated to:
jiffies = 40ms
slice_start = 40ms, slice_end = 60ms,
bytes_disp = 0;
Hence the second IO will have to wait another 30ms;
With the patch, the real rate in the first slice is 20 bytes per slice,
which is the same as expected, and slice will be updated:
jiffies=40ms,
slice_start = 20ms, slice_end = 60ms,
bytes_disp = 1;
And now, there is still 19 bytes allowed in the second slice, and the
second IO will only have to wait 10ms;
This problem will cause blktests throtl/001 failure in case of
CONFIG_HZ_100=y, fix it by preserving one extra finished slice in
throtl_trim_slice().
Fixes: e43473b7f2 ("blkio: Core implementation of throttle policy")
Reported-by: Ming Lei <ming.lei@redhat.com>
Closes: https://lore.kernel.org/linux-block/20250222092823.210318-3-yukuai1@huaweicloud.com/
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Link: https://lore.kernel.org/r/20250227120645.812815-1-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
When block drivers or the core block code perform allocations with a
frozen queue, this could try to recurse into the block device to
reclaim memory and deadlock. Thus all allocations done by a process
that froze a queue need to be done without __GFP_IO and __GFP_FS.
Instead of tying to track all of them down, force a noio scope as
part of freezing the queue.
Note that nvme is a bit of a mess here due to the non-owner freezes,
and they will be addressed separately.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20250131120352.1315351-2-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
When a process migrates to another cgroup and the original cgroup is deleted,
the restrictions of throttled bios cannot be removed. If the restrictions
are set too low, it will take a long time to complete these bios.
Refer to the process of deleting a disk to remove the restrictions and
issue bios when deleting the cgroup.
This makes difference on the behavior of throttled bios:
Before: the limit of the throttled bios can't be changed and the bios will
complete under this limit;
Now: the limit will be canceled and the throttled bios will be flushed
immediately.
References:
[1] https://lore.kernel.org/r/20220318130144.1066064-4-ming.lei@redhat.com
[2] https://lore.kernel.org/all/da861d63-58c6-3ca0-2535-9089993e9e28@huaweicloud.com/
Signed-off-by: Li Lingfeng <lilingfeng3@huawei.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20240817071108.1919729-1-lilingfeng@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This reverts commit 5b7048b897.
The main purpose of this patch is cleanup.
The throtl_adjusted_limit function was removed after
commit bf20ab538c ("blk-throttle: remove
CONFIG_BLK_DEV_THROTTLING_LOW"), so the problem of not being
able to scale after setting bps or iops to 1 will not occur.
So revert this commit that bps/iops can be set to 1.
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Xiuhong Wang <xiuhong.wang@unisoc.com>
Signed-off-by: Zhiguo Niu <zhiguo.niu@unisoc.com>
Acked-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Link: https://lore.kernel.org/r/20241016024508.3340330-1-xiuhong.wang@unisoc.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Merge tag 'for-6.12/block-20240913' of git://git.kernel.dk/linux
Pull block updates from Jens Axboe:
- MD changes via Song:
- md-bitmap refactoring (Yu Kuai)
- raid5 performance optimization (Artur Paszkiewicz)
- Other small fixes (Yu Kuai, Chen Ni)
- Add a sysfs entry 'new_level' (Xiao Ni)
- Improve information reported in /proc/mdstat (Mateusz Kusiak)
- NVMe changes via Keith:
- Asynchronous namespace scanning (Stuart)
- TCP TLS updates (Hannes)
- RDMA queue controller validation (Niklas)
- Align field names to the spec (Anuj)
- Metadata support validation (Puranjay)
- A syntax cleanup (Shen)
- Fix a Kconfig linking error (Arnd)
- New queue-depth quirk (Keith)
- Add missing unplug trace event (Keith)
- blk-iocost fixes (Colin, Konstantin)
- t10-pi modular removal and fixes (Alexey)
- Fix for potential BLKSECDISCARD overflow (Alexey)
- bio splitting cleanups and fixes (Christoph)
- Deal with folios rather than rather than pages, speeding up how the
block layer handles bigger IOs (Kundan)
- Use spinlocks rather than bit spinlocks in zram (Sebastian, Mike)
- Reduce zoned device overhead in ublk (Ming)
- Add and use sendpages_ok() for drbd and nvme-tcp (Ofir)
- Fix regression in partition error pointer checking (Riyan)
- Add support for write zeroes and rotational status in nbd (Wouter)
- Add Yu Kuai as new BFQ maintainer. The scheduler has been
unmaintained for quite a while.
- Various sets of fixes for BFQ (Yu Kuai)
- Misc fixes and cleanups (Alvaro, Christophe, Li, Md Haris, Mikhail,
Yang)
* tag 'for-6.12/block-20240913' of git://git.kernel.dk/linux: (120 commits)
nvme-pci: qdepth 1 quirk
block: fix potential invalid pointer dereference in blk_add_partition
blk_iocost: make read-only static array vrate_adj_pct const
block: unpin user pages belonging to a folio at once
mm: release number of pages of a folio
block: introduce folio awareness and add a bigger size from folio
block: Added folio-ized version of bio_add_hw_page()
block, bfq: factor out a helper to split bfqq in bfq_init_rq()
block, bfq: remove local variable 'bfqq_already_existing' in bfq_init_rq()
block, bfq: remove local variable 'split' in bfq_init_rq()
block, bfq: remove bfq_log_bfqg()
block, bfq: merge bfq_release_process_ref() into bfq_put_cooperator()
block, bfq: fix procress reference leakage for bfqq in merge chain
block, bfq: fix uaf for accessing waker_bfqq after splitting
blk-throttle: support prioritized processing of metadata
blk-throttle: remove last_low_overflow_time
drbd: Add NULL check for net_conf to prevent dereference in state validation
nvme-tcp: fix link failure for TCP auth
blk-mq: add missing unplug trace event
mtip32xx: Remove redundant null pointer checks in mtip_hw_debugfs_init()
...
Currently, blk-throttle handle all IO fifo, hence if data IO is
throttled and then meta IO is dispatched, the meta IO will have to wait
for the data IO, causing priority inversion problems.
This patch support to handle metadata first and then pay debt while
throttling data.
Test script: use cgroup v1 to throttle root cgroup, then create new
dir and file while write back is throttled
test() {
mkdir /mnt/test/xxx
touch /mnt/test/xxx/1
sync /mnt/test/xxx
sync /mnt/test/xxx
}
mkfs.ext4 -F /dev/nvme0n1 -E lazy_itable_init=0,lazy_journal_init=0
mount /dev/nvme0n1 /mnt/test
echo "259:0 $((1024*1024))" > /sys/fs/cgroup/blkio/blkio.throttle.write_bps_device
dd if=/dev/zero of=/mnt/test/foo1 bs=16M count=1 conv=fdatasync status=none &
sleep 4
time test
echo "259:0 0" > /sys/fs/cgroup/blkio/blkio.throttle.write_bps_device
sleep 1
umount /dev/nvme0n1
Test result: time cost for creating new dir and file
before this patch: 14s
after this patch: 0.1s
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20240903135149.271857-3-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The struct 'latency_bucket' and the #define 'request_bucket_index'
are unused since
commit bf20ab538c ("blk-throttle: remove CONFIG_BLK_DEV_THROTTLING_LOW")
and the 'LATENCY_BUCKET_SIZE' #define was only used by the
'request_bucket_index' define.
Remove them.
Signed-off-by: Dr. David Alan Gilbert <linux@treblig.org>
Link: https://lore.kernel.org/r/20240727155824.1000042-1-linux@treblig.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
User will configure allowed iops limit in 1s, and calculate_io_allowed()
will calculate allowed iops in the slice by:
limit * HZ / throtl_slice
However, if limit is quite low, the result can be 0, then
allowed IO in the slice is 0, this will cause missing dispatch and
control will be lower than limit.
For example, set iops_limit to 5 with HD disk, and test will found that
iops will be 3.
This is usually not a big deal, because user will unlikely to configure
such low iops limit, however, this is still a problem in the extreme
scene.
Fix the problem by making sure the wait time calculated by
tg_within_iops_limit() should allow at least one IO to be dispatched.
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20240618062108.3680835-1-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Commit bf20ab538c ("blk-throttle: remove CONFIG_BLK_DEV_THROTTLING_LOW")
attempts to revert the code change introduced by commit cd5ab1b0fc
("blk-throttle: add .low interface"). However, it leaves behind the
bps_conf[] and iops_conf[] fields in the throtl_grp structure which
aren't set anywhere in the new blk-throttle.c code but are still being
used by tg_prfill_limit() to display the limits in io.max. Now io.max
always displays the following values if a block queue is used:
<m>:<n> rbps=0 wbps=0 riops=0 wiops=0
Fix this problem by removing bps_conf[] and iops_conf[] and use bps[]
and iops[] instead to complete the revert.
Fixes: bf20ab538c ("blk-throttle: remove CONFIG_BLK_DEV_THROTTLING_LOW")
Reported-by: Justin Forbes <jforbes@redhat.com>
Closes: https://github.com/containers/podman/issues/22701#issuecomment-2120627789
Signed-off-by: Waiman Long <longman@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Link: https://lore.kernel.org/r/20240530134547.970075-1-longman@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Other cgroup policy like bfq, iocost are lazy-initialized when they are
configured for the first time for the device, but blk-throttle is
initialized unconditionally from blkcg_init_disk().
Delay initialization of blk-throttle as well, to save some cpu and
memory overhead if it's not configured.
Noted that once it's initialized, it can't be destroyed until disk
removal, even if it's disabled.
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Link: https://lore.kernel.org/r/20240509121107.3195568-3-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
One the one hand, it's marked EXPERIMENTAL since 2017, and looks like
there are no users since then, and no testers and no developers, it's
just not active at all.
On the other hand, even if the config is disabled, there are still many
fields in throtl_grp and throtl_data and many functions that are only
used for throtl low.
At last, currently blk-throtl is initialized during disk initialization,
and destroyed during disk removal, and it exposes many functions to be
called directly from block layer.
Remove throtl low to make code much more cleaner and follow up work much
easier.
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20240509121107.3195568-2-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Currently tg_prfill_limit() uses a combination of snprintf() and strcpy()
to generate the values parts of the limits string, before passing them as
arguments to seq_printf().
Convert to use only a sequence of seq_printf() calls per argument, which is
simpler.
Suggested-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: John Garry <john.g.garry@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20240327094020.3505514-1-john.g.garry@oracle.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
After calling throtl_peek_queued(), the data direction can be determined so
there is no need to call bio_data_dir() to check the direction again.
Signed-off-by: Tang Yizhou <yizhou.tang@shopee.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20240123081248.3752878-1-yizhou.tang@shopee.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Convert any user of ktime_get_ns() to use blk_time_get_ns(), and
ktime_get() to blk_time_get(), so we have a unified API for querying the
current time in nanoseconds or as ktime.
No functional changes intended, this patch just wraps ktime_get_ns()
and ktime_get() with a block helper.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Inside blkg_for_each_descendant_pre(), both
css_for_each_descendant_pre() and blkg_lookup() requires RCU read lock,
and either cgroup_assert_mutex_or_rcu_locked() or rcu_read_lock_held()
is called.
Fix the warning by adding rcu read lock.
Reported-by: Changhui Zhong <czhong@redhat.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20231117023527.3188627-2-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Inexact, we may reject some not-overflowing values incorrectly, but
they'll be on the order of exabytes allowed anyways.
This fixes divide error crash on x86 if bps_limit is not configured or
is set too high in the rare case that jiffy_elapsed is greater than HZ.
Fixes: e8368b57c0 ("blk-throttle: use calculate_io/bytes_allowed() for throtl_trim_slice()")
Fixes: 8d6bbaada2 ("blk-throttle: prevent overflow while calculating wait time")
Signed-off-by: Khazhismel Kumykov <khazhy@google.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20231020223617.2739774-1-khazhy@google.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Currently, 'carryover_ios/bytes' is not handled in throtl_trim_slice(),
for consequence, 'carryover_ios/bytes' will be used to throttle bio
multiple times, for example:
1) set iops limit to 100, and slice start is 0, slice end is 100ms;
2) current time is 0, and 10 ios are dispatched, those io won't be
throttled and io_disp is 10;
3) still at current time 0, update iops limit to 1000, carryover_ios is
updated to (0 - 10) = -10;
4) in this slice(0 - 100ms), io_allowed = 100 + (-10) = 90, which means
only 90 ios can be dispatched without waiting;
5) assume that io is throttled in slice(0 - 100ms), and
throtl_trim_slice() update silce to (100ms - 200ms). In this case,
'carryover_ios/bytes' is not cleared and still only 90 ios can be
dispatched between 100ms - 200ms.
Fix this problem by updating 'carryover_ios/bytes' in
throtl_trim_slice().
Fixes: a880ae93e5 ("blk-throttle: fix io hung due to configuration updates")
Reported-by: zhuxiaohui <zhuxiaohui.400@bytedance.com>
Link: https://lore.kernel.org/all/20230812072116.42321-1-zhuxiaohui.400@bytedance.com/
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20230816012708.1193747-5-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
carryover_ios/bytes[] can be negative in the case that ios are
dispatched in the slice in advance, and then configuration is updated.
For example:
1) set iops limit to 1000, and slice start is 0, slice end is 100ms;
2) current time is 0, and 100 ios are dispatched, those ios will not be
throttled, hence io_disp is 100;
3) still at current time 0, update iops limit to 100, then carryover_ios
is (0 - 100) = -100;
4) then, dispatch a new io at time 0, the expected result is that this
io will wait for 1s. The calculation in tg_within_iops_limit:
io_disp = 0;
io_allowed = calculate_io_allowed + carryover_ios
= 10 + (-100) = -90;
io won't be throttled if (io_disp + 1 < io_allowed) passed.
Before this patch, in step 4) (io_disp + 1 < io_allowed) is passed,
because -90 for unsigned value is very huge, and such io won't be
throttled.
Fix this problem by checking if 'io/bytes_allowed' is negative first.
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20230816012708.1193747-3-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
'carryover_bytes/ios' can be negative, indicate that some bio is
dispatched in advance within slice while configuration is updated.
Print a huge value is not user-friendly.
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20230816012708.1193747-2-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
After commit f382fb0bce ("block: remove legacy IO schedulers"),
blkio.throttle.io_serviced and blkio.throttle.io_service_bytes become
the only stable io stats interface of cgroup v1, and these statistics
are done in the blk-throttle code. But the current code only counts the
bios that are actually throttled. When the user does not add the throttle
limit, the io stats for cgroup v1 has nothing. I fix it according to the
statistical method of v2, and made it count all ios accurately.
Fixes: a7b36ee6ba ("block: move blk-throtl fast path inline")
Tested-by: Andrea Righi <andrea.righi@canonical.com>
Signed-off-by: Jinke Han <hanjinke.666@bytedance.com>
Acked-by: Muchun Song <songmuchun@bytedance.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20230507170631.89607-1-hanjinke.666@bytedance.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
blk_throtl_register() will unconditionally enable blk-stat for gendisk
when register, even when we have no BLK_DEV_THROTTLING_LOW config.
Since the kernel always has only BLK_DEV_THROTTLING config and the
BLK_DEV_THROTTLING_LOW config is still in EXPERIMENTAL state, we can
just skip blk-stat when !BLK_DEV_THROTTLING_LOW.
Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20230413062805.2081970-2-chengming.zhou@linux.dev
Signed-off-by: Jens Axboe <axboe@kernel.dk>
We want to support lazy init of rq-qos policies so that iolatency is enabled
lazily on configuration instead of gendisk initialization. The way blkg
config helpers are structured now is a bit awkward for that. Let's
restructure:
* blkcg_conf_open_bdev() is renamed to blkg_conf_open_bdev(). The blkcg_
prefix was used because the bdev opening step is blkg-independent.
However, the distinction is too subtle and confuses more than helps. Let's
switch to blkg prefix so that it's consistent with the type and other
helper names.
* struct blkg_conf_ctx now remembers the original input string and is always
initialized by the new blkg_conf_init().
* blkg_conf_open_bdev() is updated to take a pointer to blkg_conf_ctx like
blkg_conf_prep() and can be called multiple times safely. Instead of
modifying the double pointer to input string directly,
blkg_conf_open_bdev() now sets blkg_conf_ctx->body.
* blkg_conf_finish() is renamed to blkg_conf_exit() for symmetry and now
must be called on all blkg_conf_ctx's which were initialized with
blkg_conf_init().
Combined, this allows the users to either open the bdev first or do it
altogether with blkg_conf_prep() which will help implementing lazy init of
rq-qos policies.
blkg_conf_init/exit() will also be used implement synchronization against
device removal. This is necessary because iolat / iocost are configured
through cgroupfs instead of one of the files under /sys/block/DEVICE. As
cgroupfs operations aren't synchronized with block layer, the lazy init and
other configuration operations may race against device removal. This patch
makes blkg_conf_init/exit() used consistently for all cgroup-orginating
configurations making them a good place to implement explicit
synchronization.
Users are updated accordingly. No behavior change is intended by this patch.
v2: bfq wasn't updated in v1 causing a build error. Fixed.
v3: Update the description to include future use of blkg_conf_init/exit() as
synchronization points.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Yu Kuai <yukuai1@huaweicloud.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20230413000649.115785-3-tj@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Guenter Roeck