On Fri, Sep 15, 2017 at 05:29:53PM +0000, Bart Van Assche wrote: > On Sat, 2017-09-16 at 00:44 +0800, Ming Lei wrote: > > blk-mq will rerun queue via RESTART after one request is completion, > > so not necessary to wait random time for requeuing, it should trust > > blk-mq to do it. > > > > Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx> > > --- > > drivers/md/dm-mpath.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c > > index 96aedaac2c64..f5a1088a6e79 100644 > > --- a/drivers/md/dm-mpath.c > > +++ b/drivers/md/dm-mpath.c > > @@ -505,7 +505,7 @@ static int multipath_clone_and_map(struct dm_target *ti, struct request *rq, > > atomic_inc(&m->pg_init_in_progress); > > activate_or_offline_path(pgpath); > > } > > - return DM_MAPIO_DELAY_REQUEUE; > > + return DM_MAPIO_REQUEUE; > > } > > clone->bio = clone->biotail = NULL; > > clone->rq_disk = bdev->bd_disk; > > So you are reverting the patch below? Thank you very much. > > commit 1c23484c355ec360ca2f37914f8a4802c6baeead > Author: Bart Van Assche <bart.vanassche@xxxxxxx> > Date: Wed Aug 9 11:32:12 2017 -0700 > > dm mpath: do not lock up a CPU with requeuing activity > > When using the block layer in single queue mode, get_request() > returns ERR_PTR(-EAGAIN) if the queue is dying and the REQ_NOWAIT > flag has been passed to get_request(). Avoid that the kernel > reports soft lockup complaints in this case due to continuous > requeuing activity. What is the continuous requeuing activity? In case of BLK_STS_RESOURCE, blk-mq's SCHED_RESTART(see blk_mq_sched_dispatch_requests()) will be triggered, then this rq will be dispatched again after one rq is completed. -- Ming -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
