From: Jens Axboe <axboe@xxxxxxxxx> [ Upstream commit cb2ac2912a9ca7d3d26291c511939a41361d2d83 ] Dexuan reports that he's seeing spikes of very heavy CPU utilization when running 24 disks and using the 'none' scheduler. This happens off the sched restart path, because SCSI requires the queue to be restarted async, and hence we're hammering on mod_delayed_work_on() to ensure that the work item gets run appropriately. Avoid hammering on the timer and just use queue_work_on() if no delay has been specified. Reported-and-tested-by: Dexuan Cui <decui@xxxxxxxxxxxxx> Link: https://lore.kernel.org/linux-block/BYAPR21MB1270C598ED214C0490F47400BF719@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/ Reviewed-by: Ming Lei <ming.lei@xxxxxxxxxx> Signed-off-by: Jens Axboe <axboe@xxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- block/blk-core.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/block/blk-core.c b/block/blk-core.c index 5808baa950c35..78b7a21cf1d69 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -1669,6 +1669,8 @@ EXPORT_SYMBOL(kblockd_schedule_work_on); int kblockd_mod_delayed_work_on(int cpu, struct delayed_work *dwork, unsigned long delay) { + if (!delay) + return queue_work_on(cpu, kblockd_workqueue, &dwork->work); return mod_delayed_work_on(cpu, kblockd_workqueue, dwork, delay); } EXPORT_SYMBOL(kblockd_mod_delayed_work_on); -- 2.34.1
