From 018e5987b57589e6e9089c2d2ef31db4e7519fd5 Mon Sep 17 00:00:00 2001 From: Kevin Wolf Date: Wed, 10 May 2023 22:36:00 +0200 Subject: blockjob: Adhere to rate limit even when reentered early When jobs are sleeping, for example to enforce a given rate limit, they can be reentered early, in particular in order to get paused, to update the rate limit or to get cancelled. Before this patch, they behave in this case as if they had fully completed their rate limiting delay. This means that requests are sped up beyond their limit, violating the constraints that the user gave us. Change the block jobs to sleep in a loop until the necessary delay is completed, while still allowing cancelling them immediately as well pausing (handled by the pause point in job_sleep_ns()) and updating the rate limit. This change is also motivated by iotests cases being prone to fail because drain operations pause and unpause them so often that block jobs complete earlier than they are supposed to. In particular, the next commit would fail iotests 030 without this change. Signed-off-by: Kevin Wolf Message-Id: <20230510203601.418015-8-kwolf@redhat.com> Reviewed-by: Eric Blake Signed-off-by: Kevin Wolf --- blockjob.c | 22 ++++++++++++++++++++-- 1 file changed, 20 insertions(+), 2 deletions(-) (limited to 'blockjob.c') diff --git a/blockjob.c b/blockjob.c index 659c3cb..913da3c 100644 --- a/blockjob.c +++ b/blockjob.c @@ -319,10 +319,28 @@ static bool block_job_set_speed(BlockJob *job, int64_t speed, Error **errp) return block_job_set_speed_locked(job, speed, errp); } -int64_t block_job_ratelimit_get_delay(BlockJob *job, uint64_t n) +void block_job_ratelimit_processed_bytes(BlockJob *job, uint64_t n) { IO_CODE(); - return ratelimit_calculate_delay(&job->limit, n); + ratelimit_calculate_delay(&job->limit, n); +} + +void block_job_ratelimit_sleep(BlockJob *job) +{ + uint64_t delay_ns; + + /* + * Sleep at least once. If the job is reentered early, keep waiting until + * we've waited for the full time that is necessary to keep the job at the + * right speed. + * + * Make sure to recalculate the delay after each (possibly interrupted) + * sleep because the speed can change while the job has yielded. + */ + do { + delay_ns = ratelimit_calculate_delay(&job->limit, 0); + job_sleep_ns(&job->job, delay_ns); + } while (delay_ns && !job_is_cancelled(&job->job)); } BlockJobInfo *block_job_query_locked(BlockJob *job, Error **errp) -- cgit v1.1