Messages in this thread | | | Date | Wed, 3 Jun 2015 00:53:45 +0900 | Subject | Re: [PATCH 2/2] null_blk: restart request processing on completion handler | From | Akinobu Mita <> |
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2015-06-02 8:35 GMT+09:00 Akinobu Mita <akinobu.mita@gmail.com>: > When irqmode=2 (IRQ completion handler is timer) and queue_mode=1 > (Block interface to use is rq), the completion handler should restart > request handling for any pending requests on a queue because request > processing stops when the number of commands are queued more than > hw_queue_depth (null_rq_prep_fn returns BLKPREP_DEFER). > > Without this change, the following command cannot finish. > > # modprobe null_blk irqmode=2 queue_mode=1 hw_queue_depth=1 > # fio --name=t --rw=read --size=1g --direct=1 \ > --ioengine=libaio --iodepth=64 --filename=/dev/nullb0 > > Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com> > Cc: Jens Axboe <axboe@fb.com> > --- > drivers/block/null_blk.c | 12 ++++++++++++ > 1 file changed, 12 insertions(+) > > diff --git a/drivers/block/null_blk.c b/drivers/block/null_blk.c > index 6f0a58e..6f9b753 100644 > --- a/drivers/block/null_blk.c > +++ b/drivers/block/null_blk.c > @@ -243,6 +243,17 @@ static enum hrtimer_restart null_cmd_timer_expired(struct hrtimer *timer) > cmd = container_of(entry, struct nullb_cmd, ll_list); > entry = entry->next; > end_cmd(cmd); > + > + if (cmd->rq) { > + struct request_queue *q = cmd->rq->q; > + > + if (!q->mq_ops && blk_queue_stopped(q)) { > + spin_lock(q->queue_lock); > + if (blk_queue_stopped(q)) > + blk_start_queue(q);
Should 'blk_start_queue(q)' be:
queue_flag_clear(QUEUE_FLAG_STOPPED, q); blk_run_queue_async(q); ?
Otherwise, all pending requests on a queue are completed by this timer handler execution without needing next timer expiry.
> + spin_unlock(q->queue_lock); > + } > + } > } while (entry); > } > > @@ -334,6 +345,7 @@ static int null_rq_prep_fn(struct request_queue *q, struct request *req) > req->special = cmd; > return BLKPREP_OK; > } > + blk_stop_queue(q); > > return BLKPREP_DEFER; > } > -- > 1.9.1 >
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