| Message ID | 1523865336-17326-1-git-send-email-jianchao.w.wang@oracle.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Mon, Apr 16, 2018 at 03:55:36PM +0800, Jianchao Wang wrote: > When get budget fails, blk_mq_sched_dispatch_requests does not do > anything to ensure the hctx to be restarted. We can survive from > this, because only the scsi implements .get_budget and it always > runs the hctx queues when request is completed. Exactly, that is why we don't handle the failure before dequeuing request. I suggest to just document this usage now. > > Signed-off-by: Jianchao Wang <jianchao.w.wang@oracle.com> > --- > block/blk-mq-sched.c | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) > > diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c > index 25c14c5..49e7cd9 100644 > --- a/block/blk-mq-sched.c > +++ b/block/blk-mq-sched.c > @@ -102,8 +102,10 @@ static void blk_mq_do_dispatch_sched(struct blk_mq_hw_ctx *hctx) > !e->type->ops.mq.has_work(hctx)) > break; > > - if (!blk_mq_get_dispatch_budget(hctx)) > + if (!blk_mq_get_dispatch_budget(hctx)) { > + blk_mq_sched_mark_restart_hctx(hctx); The RESTART flag still may not take into effect if all requests are completed before calling blk_mq_sched_mark_restart_hctx(). > break; > + } > > rq = e->type->ops.mq.dispatch_request(hctx); > if (!rq) { > @@ -148,8 +150,10 @@ static void blk_mq_do_dispatch_ctx(struct blk_mq_hw_ctx *hctx) > if (!sbitmap_any_bit_set(&hctx->ctx_map)) > break; > > - if (!blk_mq_get_dispatch_budget(hctx)) > + if (!blk_mq_get_dispatch_budget(hctx)) { > + blk_mq_sched_mark_restart_hctx(hctx); Same with above. Thanks, Ming
Hi Ming Thanks for your kindly response. On 04/16/2018 04:15 PM, Ming Lei wrote: >> - if (!blk_mq_get_dispatch_budget(hctx)) >> + if (!blk_mq_get_dispatch_budget(hctx)) { >> + blk_mq_sched_mark_restart_hctx(hctx); > The RESTART flag still may not take into effect if all requests are > completed before calling blk_mq_sched_mark_restart_hctx(). > Yes, this is indeed a very tricky scenario. Sincerely Jianchao
diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c index 25c14c5..49e7cd9 100644 --- a/block/blk-mq-sched.c +++ b/block/blk-mq-sched.c @@ -102,8 +102,10 @@ static void blk_mq_do_dispatch_sched(struct blk_mq_hw_ctx *hctx) !e->type->ops.mq.has_work(hctx)) break; - if (!blk_mq_get_dispatch_budget(hctx)) + if (!blk_mq_get_dispatch_budget(hctx)) { + blk_mq_sched_mark_restart_hctx(hctx); break; + } rq = e->type->ops.mq.dispatch_request(hctx); if (!rq) { @@ -148,8 +150,10 @@ static void blk_mq_do_dispatch_ctx(struct blk_mq_hw_ctx *hctx) if (!sbitmap_any_bit_set(&hctx->ctx_map)) break; - if (!blk_mq_get_dispatch_budget(hctx)) + if (!blk_mq_get_dispatch_budget(hctx)) { + blk_mq_sched_mark_restart_hctx(hctx); break; + } rq = blk_mq_dequeue_from_ctx(hctx, ctx); if (!rq) {
When get budget fails, blk_mq_sched_dispatch_requests does not do anything to ensure the hctx to be restarted. We can survive from this, because only the scsi implements .get_budget and it always runs the hctx queues when request is completed. Signed-off-by: Jianchao Wang <jianchao.w.wang@oracle.com> --- block/blk-mq-sched.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)