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| author | Yu Kuai <yukuai3@huawei.com> | 2022-08-29 04:22:40 +0200 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2022-09-12 08:19:48 +0200 |
| commit | a880ae93e5b5bb5d8d5500077a391e3f5ec7715c (patch) | |
| tree | 62e67e5081b5436c3ab91445387c6382f039cf0b /block/blk-throttle.h | |
| parent | blk-throttle: factor out code to calculate ios/bytes_allowed (diff) | |
| download | linux-a880ae93e5b5bb5d8d5500077a391e3f5ec7715c.tar.xz linux-a880ae93e5b5bb5d8d5500077a391e3f5ec7715c.zip | |
blk-throttle: fix io hung due to configuration updates
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>
Diffstat (limited to 'block/blk-throttle.h')
| -rw-r--r-- | block/blk-throttle.h | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/block/blk-throttle.h b/block/blk-throttle.h index ee7299e6dea9..66b4292b1b92 100644 --- a/block/blk-throttle.h +++ b/block/blk-throttle.h @@ -121,6 +121,15 @@ struct throtl_grp { uint64_t last_bytes_disp[2]; unsigned int last_io_disp[2]; + /* + * The following two fields are updated when new configuration is + * submitted while some bios are still throttled, they record how many + * bytes/ios are waited already in previous configuration, and they will + * be used to calculate wait time under new configuration. + */ + uint64_t carryover_bytes[2]; + unsigned int carryover_ios[2]; + unsigned long last_check_time; unsigned long latency_target; /* us */ |