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>
While del_gendisk ensures there is no outstanding I/O on the queue,
it can't prevent block layer users from building new I/O.
This leads to a NULL ->root_blkg reference in bio_associate_blkg when
allocating a new bio on a shut down file system. Delay freeing the
blk-cgroup subsystems from del_gendisk until disk_release to make
sure the blkg and throttle information is still avaіlable for bio
submitters, even if those bios will immediately fail.
This now can cause a case where disk_release is called on a disk
that hasn't been added. That's mostly harmless, except for a case
in blk_throttl_exit that now needs to check for a NULL ->td pointer.
Fixes: 178fa7d498 ("blk-cgroup: delay blk-cgroup initialization until add_disk")
Reported-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20230208063514.171485-1-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
cgroup information only makes sense on a live gendisk that allows
file system I/O (which includes the raw block device). So move over
the cgroup related members.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Andreas Herrmann <aherrmann@suse.de>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20230203150400.3199230-20-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
No need to the request_queue here, pass a gendisk and extract the
node ids from that.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Andreas Herrmann <aherrmann@suse.de>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20230203150400.3199230-18-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Prepare for storing the blkcg information in the gendisk instead of
the request_queue.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Andreas Herrmann <aherrmann@suse.de>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20230203150400.3199230-17-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Currently each blkcg_gq holds a request_queue reference, which is what
is used in the policies. But a lot of these interfaces will move over to
use a gendisk, so store a disk in struct blkcg_gq and hold a reference to
it.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Andreas Herrmann <aherrmann@suse.de>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20230203150400.3199230-7-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
There is no need to update tg->slice_start[rw] to start when they are
equal already. So remove "eq" part of check before update slice_start.
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Kemeng Shi <shikemeng@huawei.com>
Link: https://lore.kernel.org/r/20221205115709.251489-10-shikemeng@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
There is no need to check elapsed time from last upgrade for each node in
hierarchy. Move this check before traversing as throtl_can_upgrade do
to remove repeat check.
Reported-by: kernel test robot <lkp@intel.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Kemeng Shi <shikemeng@huawei.com>
Link: https://lore.kernel.org/r/20221205115709.251489-9-shikemeng@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Function tg_last_low_overflow_time is called with intermediate node as
following:
throtl_hierarchy_can_downgrade
throtl_tg_can_downgrade
tg_last_low_overflow_time
throtl_hierarchy_can_upgrade
throtl_tg_can_upgrade
tg_last_low_overflow_time
throtl_hierarchy_can_downgrade/throtl_hierarchy_can_upgrade will traverse
from leaf node to sub-root node and pass traversed intermediate node
to tg_last_low_overflow_time.
No such limit could be found from context and implementation of
tg_last_low_overflow_time, so remove this limit in comment.
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Kemeng Shi <shikemeng@huawei.com>
Link: https://lore.kernel.org/r/20221205115709.251489-8-shikemeng@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Commit c79892c557 ("blk-throttle: add upgrade logic for LIMIT_LOW
state") added upgrade logic for low limit and methioned that
1. "To determine if a cgroup exceeds its limitation, we check if the cgroup
has pending request. Since cgroup is throttled according to the limit,
pending request means the cgroup reaches the limit."
2. "If a cgroup has limit set for both read and write, we consider the
combination of them for upgrade. The reason is read IO and write IO can
interfere with each other. If we do the upgrade based in one direction IO,
the other direction IO could be severly harmed."
Besides, we also determine that cgroup reaches low limit if low limit is 0,
see comment in throtl_tg_can_upgrade.
Collect the information above, the desgin of upgrade check is as following:
1.The low limit is reached if limit is zero or io is already queued.
2.Cgroup will pass upgrade check if low limits of READ and WRITE are both
reached.
Simpfy the check code described above to removce repeat check and improve
readability. There is no functional change.
Detail equivalence proof is as following:
All replaced conditions to return true are as following:
condition 1
(!read_limit && !write_limit)
condition 2
read_limit && sq->nr_queued[READ] &&
(!write_limit || sq->nr_queued[WRITE])
condition 3
write_limit && sq->nr_queued[WRITE] &&
(!read_limit || sq->nr_queued[READ])
Transferring condition 2 as following:
(read_limit && sq->nr_queued[READ]) &&
(!write_limit || sq->nr_queued[WRITE])
is equivalent to
(read_limit && sq->nr_queued[READ]) &&
(!write_limit || (write_limit && sq->nr_queued[WRITE]))
is equivalent to
condition 2.1
(read_limit && sq->nr_queued[READ] &&
!write_limit) ||
condition 2.2
(read_limit && sq->nr_queued[READ] &&
(write_limit && sq->nr_queued[WRITE]))
Transferring condition 3 as following:
write_limit && sq->nr_queued[WRITE] &&
(!read_limit || sq->nr_queued[READ])
is equivalent to
(write_limit && sq->nr_queued[WRITE]) &&
(!read_limit || (read_limit && sq->nr_queued[READ]))
is equivalent to
condition 3.1
((write_limit && sq->nr_queued[WRITE]) &&
!read_limit) ||
condition 3.2
((write_limit && sq->nr_queued[WRITE]) &&
(read_limit && sq->nr_queued[READ]))
Condition 3.2 is the same as condition 2.2, so all conditions we get to
return are as following:
(!read_limit && !write_limit) (1)
(!read_limit && (write_limit && sq->nr_queued[WRITE])) (3.1)
((read_limit && sq->nr_queued[READ]) && !write_limit) (2.1)
((write_limit && sq->nr_queued[WRITE]) &&
(read_limit && sq->nr_queued[READ])) (2.2)
As we can extract conditions "(a1 || a2) && (b1 || b2)" to:
a1 && b1
a1 && b2
a2 && b1
ab && b2
Considering that:
a1 = !read_limit
a2 = read_limit && sq->nr_queued[READ]
b1 = !write_limit
b2 = write_limit && sq->nr_queued[WRITE]
We can pack replaced conditions to
(!read_limit || (read_limit && sq->nr_queued[READ])) &&
(!write_limit || (write_limit && sq->nr_queued[WRITE]))
which is equivalent to
(!read_limit || sq->nr_queued[READ]) &&
(!write_limit || sq->nr_queued[WRITE])
Reported-by: kernel test robot <lkp@intel.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Kemeng Shi <shikemeng@huawei.com>
Link: https://lore.kernel.org/r/20221205115709.251489-6-shikemeng@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
In C language, When executing "if (expression1 && expression2)" and
expression1 return false, the expression2 may not be executed.
For "tg_within_bps_limit(tg, bio, bps_limit, &bps_wait) &&
tg_within_iops_limit(tg, bio, iops_limit, &iops_wait))", if bps is
limited, tg_within_bps_limit will return false and
tg_within_iops_limit will not be called. So even bps and iops are
both limited, iops_wait will not be calculated and is always zero.
So wait time of iops is always ignored.
Fix this by always calling tg_within_bps_limit and tg_within_iops_limit
to get wait time for both bps and iops.
Observed that:
1. Wait time in tg_within_iops_limit/tg_within_bps_limit need always
be stored as wait argument is always passed.
2. wait time is stored to zero if iops/bps is limited otherwise non-zero
is stored.
Simpfy tg_within_iops_limit/tg_within_bps_limit by removing wait argument
and return wait time directly. Caller tg_may_dispatch checks if wait time
is zero to find if iops/bps is limited.
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Kemeng Shi <shikemeng@huawei.com>
Link: https://lore.kernel.org/r/20221205115709.251489-5-shikemeng@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Ignore cgroup without io queued in blk_throtl_cancel_bios for two
reasons:
1. Save cpu cycle for trying to dispatch cgroup which is no io queued.
2. Avoid non-consistent state that cgroup is inserted to service queue
without THROTL_TG_PENDING set as tg_update_disptime will unconditional
re-insert cgroup to service queue. If we are on the default hierarchy,
IO dispatched from child in tg_dispatch_one_bio will trigger inserting
cgroup to service queue without erase first and ruin the tree.
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Kemeng Shi <shikemeng@huawei.com>
Link: https://lore.kernel.org/r/20221205115709.251489-4-shikemeng@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Consider situation as following (on the default hierarchy):
HDD
|
root (bps limit: 4k)
|
child (bps limit :8k)
|
fio bs=8k
Rate of fio is supposed to be 4k, but result is 8k. Reason is as
following:
Size of single IO from fio is larger than bytes allowed in one
throtl_slice in child, so IOs are always queued in child group first.
When queued IOs in child are dispatched to parent group, BIO_BPS_THROTTLED
is set and these IOs will not be limited by tg_within_bps_limit anymore.
Fix this by only set BIO_BPS_THROTTLED when the bio traversed the entire
tree.
There patch has no influence on situation which is not on the default
hierarchy as each group is a single root group without parent.
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Kemeng Shi <shikemeng@huawei.com>
Link: https://lore.kernel.org/r/20221205115709.251489-3-shikemeng@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
On the default hierarchy (cgroup2), the throttle interface files don't
exist in the root cgroup, so the ablity to limit the whole system
by configuring root group is not existing anymore. In general, cgroup
doesn't wanna be in the business of restricting resources at the
system level, so correct the stale comment that we can limit whole
system to we can only limit subtree.
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Kemeng Shi <shikemeng@huawei.com>
Link: https://lore.kernel.org/r/20221205115709.251489-2-shikemeng@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Pass the gendisk to blk_throtl_cancel_bios as part of moving the
blk-cgroup infrastructure to be gendisk based.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Andreas Herrmann <aherrmann@suse.de>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220921180501.1539876-15-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Pass the gendisk to blk_throtl_register_queue as part of moving the
blk-cgroup infrastructure to be gendisk based.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Andreas Herrmann <aherrmann@suse.de>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220921180501.1539876-14-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Pass the gendisk to blk_throtl_init and blk_throtl_exit as part of moving
the blk-cgroup infrastructure to be gendisk based.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Andreas Herrmann <aherrmann@suse.de>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220921180501.1539876-13-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
"tg->has_rules" is extended to "tg->has_rules_iops/bps", thus bios that
don't need to be throttled can be checked accurately.
With this patch, bio will be throttled if:
1) Bio is read/write, and corresponding read/write iops limit exist.
2) If corresponding doesn't exist, corresponding bps limit exist and
bio is not throttled before.
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220921095309.1481289-3-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Currently, "tg->has_rules" and "tg->flags & THROTL_TG_HAS_IOPS_LIMIT"
both try to bypass bios that don't need to be throttled, however, they are
a little redundant and both not perfect:
1) "tg->has_rules" only distinguish read and write, but not iops and bps
limit.
2) "tg->flags & THROTL_TG_HAS_IOPS_LIMIT" only check if iops limit
exist, read and write is not distinguished, and bps limit is not
checked.
tg->has_rules will extended to distinguish bps and iops in the following
patch. There is no need to keep the flag.
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220921095309.1481289-2-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
tg_update_disptime() only need to adjust postion for 'tg' in
'parent_sq', there is no need to call throtl_enqueue/dequeue_tg(),
since they will set/clear flag THROTL_TG_PENDING and increase/decrease
nr_pending, which is useless. By the way, clear the flag/decrease
nr_pending while there are still throttled bios is not good for debugging.
There are no functional changes.
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220827101637.1775111-4-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
It's a little weird to call throtl_dequeue_tg() unconditionally in
throtl_select_dispatch(), since it will be called in tg_update_disptime()
again if some bio is still throttled. Thus call it later if there are no
throttled bio. There are no functional changes.
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220827101637.1775111-3-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
If new configuration is submitted while a bio is throttled, then new
waiting time is recalculated regardless that the bio might already wait
for some time:
tg_conf_updated
throtl_start_new_slice
tg_update_disptime
throtl_schedule_next_dispatch
Then io hung can be triggered by always submmiting new configuration
before the throttled bio is dispatched.
Fix the problem by respecting the time that throttled bio already waited.
In order to do that, add new fields to record how many bytes/io are
waited, and use it to calculate wait time for throttled bio under new
configuration.
Some simple test:
1)
cd /sys/fs/cgroup/blkio/
echo $$ > cgroup.procs
echo "8:0 2048" > blkio.throttle.write_bps_device
{
sleep 2
echo "8:0 1024" > blkio.throttle.write_bps_device
} &
dd if=/dev/zero of=/dev/sda bs=8k count=1 oflag=direct
2)
cd /sys/fs/cgroup/blkio/
echo $$ > cgroup.procs
echo "8:0 1024" > blkio.throttle.write_bps_device
{
sleep 4
echo "8:0 2048" > blkio.throttle.write_bps_device
} &
dd if=/dev/zero of=/dev/sda bs=8k count=1 oflag=direct
test results: io finish time
before this patch with this patch
1) 10s 6s
2) 8s 6s
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Michal Koutný <mkoutny@suse.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220829022240.3348319-5-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
No functional changes, new apis will be used in later patches to
calculate wait time for throttled bios when new configuration is
submitted.
Noted this patch also rename tg_with_in_iops/bps_limit() to
tg_within_iops/bps_limit().
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220829022240.3348319-4-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
