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authorYu Kuai <yukuai3@huawei.com>2023-08-16 09:27:08 +0800
committerJens Axboe <axboe@kernel.dk>2023-08-30 10:15:01 -0600
commiteead0056648cef49d7b15c07ae612fa217083165 (patch)
tree5945d041f446ea086d237697ba969079d07d6082
parente8368b57c006dc0e02dcd8a9dc9f2060ff5476fe (diff)
blk-throttle: consider 'carryover_ios/bytes' in throtl_trim_slice()
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: a880ae93e5b5 ("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>
-rw-r--r--block/blk-throttle.c21
1 files changed, 13 insertions, 8 deletions
diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index 69a994156772..38a881cf97d0 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -729,8 +729,9 @@ static u64 calculate_bytes_allowed(u64 bps_limit, unsigned long jiffy_elapsed)
/* Trim the used slices and adjust slice start accordingly */
static inline void throtl_trim_slice(struct throtl_grp *tg, bool rw)
{
- unsigned long time_elapsed, io_trim;
- u64 bytes_trim;
+ unsigned long time_elapsed;
+ long long bytes_trim;
+ int io_trim;
BUG_ON(time_before(tg->slice_end[rw], tg->slice_start[rw]));
@@ -758,17 +759,21 @@ static inline void throtl_trim_slice(struct throtl_grp *tg, bool rw)
return;
bytes_trim = calculate_bytes_allowed(tg_bps_limit(tg, rw),
- time_elapsed);
- io_trim = calculate_io_allowed(tg_iops_limit(tg, rw), time_elapsed);
- if (!bytes_trim && !io_trim)
+ time_elapsed) +
+ tg->carryover_bytes[rw];
+ io_trim = calculate_io_allowed(tg_iops_limit(tg, rw), time_elapsed) +
+ tg->carryover_ios[rw];
+ if (bytes_trim <= 0 && io_trim <= 0)
return;
- if (tg->bytes_disp[rw] >= bytes_trim)
+ tg->carryover_bytes[rw] = 0;
+ if ((long long)tg->bytes_disp[rw] >= bytes_trim)
tg->bytes_disp[rw] -= bytes_trim;
else
tg->bytes_disp[rw] = 0;
- if (tg->io_disp[rw] >= io_trim)
+ tg->carryover_ios[rw] = 0;
+ if ((int)tg->io_disp[rw] >= io_trim)
tg->io_disp[rw] -= io_trim;
else
tg->io_disp[rw] = 0;
@@ -776,7 +781,7 @@ static inline void throtl_trim_slice(struct throtl_grp *tg, bool rw)
tg->slice_start[rw] += time_elapsed;
throtl_log(&tg->service_queue,
- "[%c] trim slice nr=%lu bytes=%llu io=%lu start=%lu end=%lu jiffies=%lu",
+ "[%c] trim slice nr=%lu bytes=%lld io=%d start=%lu end=%lu jiffies=%lu",
rw == READ ? 'R' : 'W', time_elapsed / tg->td->throtl_slice,
bytes_trim, io_trim, tg->slice_start[rw], tg->slice_end[rw],
jiffies);