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Groups > linux.kernel > #1731324
| From | Ming Lei <ming.lei@redhat.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH] blk-mq: put the driver tag of nxt rq before first one is requeued |
| Date | 2017-09-13 03:30 +0200 |
| Message-ID | <up4F4-El-3@gated-at.bofh.it> (permalink) |
| References | <uoPwm-7PF-21@gated-at.bofh.it> <uoQC6-8vg-11@gated-at.bofh.it> <up4lI-wf-11@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Wed, Sep 13, 2017 at 09:01:25AM +0800, jianchao.wang wrote:
> Hi ming
>
> On 09/12/2017 06:23 PM, Ming Lei wrote:
> >> @@ -1029,14 +1029,20 @@ bool blk_mq_dispatch_rq_list(struct request_queue *q, struct list_head *list)
> >> if (list_empty(list))
> >> bd.last = true;
> >> else {
> >> - struct request *nxt;
> >> -
> >> nxt = list_first_entry(list, struct request, queuelist);
> >> bd.last = !blk_mq_get_driver_tag(nxt, NULL, false);
> >> }
> >>
> >> ret = q->mq_ops->queue_rq(hctx, &bd);
> >> if (ret == BLK_STS_RESOURCE) {
> >> + /*
> >> + * If an I/O scheduler has been configured and we got a
> >> + * driver tag for the next request already, free it again.
> >> + */
> >> + if (!list_empty(list)) {
> >> + nxt = list_first_entry(list, struct request, queuelist);
> >> + blk_mq_put_driver_tag(nxt);
> >> + }
> > The following way might be more simple and clean:
> >
> > if (nxt)
> > blk_mq_put_driver_tag(nxt);
> >
> > meantime 'nxt' need to be cleared inside the 'if (list_empty(list))'
> > before .queue_rq().
>
> I had ever thought about that, but to avoid add extra command in the
> fast path, I made the patch above.
Got it, so how about changing to the following way simply:
if (nxt && !list_empty(list))
blk_mq_put_driver_tag(nxt);
--
Ming
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[PATCH] blk-mq: put the driver tag of nxt rq before first one is requeued Jianchao Wang <jianchao.w.wang@oracle.com> - 2017-09-12 11:20 +0200
Re: [PATCH] blk-mq: put the driver tag of nxt rq before first one is requeued Ming Lei <ming.lei@redhat.com> - 2017-09-12 12:30 +0200
Re: [PATCH] blk-mq: put the driver tag of nxt rq before first one is requeued "jianchao.wang" <jianchao.w.wang@oracle.com> - 2017-09-13 03:10 +0200
Re: [PATCH] blk-mq: put the driver tag of nxt rq before first one is requeued Ming Lei <ming.lei@redhat.com> - 2017-09-13 03:30 +0200
Re: [PATCH] blk-mq: put the driver tag of nxt rq before first one is requeued "jianchao.wang" <jianchao.w.wang@oracle.com> - 2017-09-13 03:50 +0200
Re: [PATCH] blk-mq: put the driver tag of nxt rq before first one is requeued Ming Lei <ming.lei@redhat.com> - 2017-09-13 04:00 +0200
Re: [PATCH] blk-mq: put the driver tag of nxt rq before first one is requeued Jens Axboe <axboe@kernel.dk> - 2017-09-13 04:30 +0200
Re: [PATCH] blk-mq: put the driver tag of nxt rq before first one is requeued "jianchao.wang" <jianchao.w.wang@oracle.com> - 2017-09-13 04:50 +0200
Re: [PATCH] blk-mq: put the driver tag of nxt rq before first one is requeued Jens Axboe <axboe@kernel.dk> - 2017-09-13 04:50 +0200
Re: [PATCH] blk-mq: put the driver tag of nxt rq before first one is requeued "jianchao.wang" <jianchao.w.wang@oracle.com> - 2017-09-13 05:40 +0200
Re: [PATCH] blk-mq: put the driver tag of nxt rq before first one is requeued Jens Axboe <axboe@kernel.dk> - 2017-09-13 06:00 +0200
Re: [PATCH] blk-mq: put the driver tag of nxt rq before first one is requeued "jianchao.wang" <jianchao.w.wang@oracle.com> - 2017-09-13 06:00 +0200
Re: [PATCH] blk-mq: put the driver tag of nxt rq before first one is requeued Ming Lei <ming.lei@redhat.com> - 2017-09-13 06:00 +0200
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