On 02/06/2017 12:24 PM, Omar Sandoval wrote:
> From: Omar Sandoval <osandov@xxxxxx>
>
> In blk_mq_sched_dispatch_requests(), we call blk_mq_sched_mark_restart()
> after we dispatch requests left over on our hardware queue dispatch
> list. This is so we'll go back and dispatch requests from the scheduler.
> In this case, it's only necessary to restart the hardware queue that we
> are running; there's no reason to run other hardware queues just because
> we are using shared tags.
>
> So, split out blk_mq_sched_mark_restart() into two operations, one for
> just the hardware queue and one for the whole request queue. The core
> code uses both, and I/O schedulers may also want to use them.
>
> Signed-off-by: Omar Sandoval <osandov@xxxxxx>
> ---
> Patch based on block/for-next.
>
> block/blk-mq-sched.c | 2 +-
> block/blk-mq-sched.h | 25 ++++++++++++++++++-------
> block/blk-mq.c | 5 ++++-
> 3 files changed, 23 insertions(+), 9 deletions(-)
>
> diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
> index ee455e7cf9d8..7538565359ea 100644
> --- a/block/blk-mq-sched.c
> +++ b/block/blk-mq-sched.c
> @@ -201,7 +201,7 @@ void blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx)
> * needing a restart in that case.
> */
> if (!list_empty(&rq_list)) {
> - blk_mq_sched_mark_restart(hctx);
> + blk_mq_sched_mark_restart_hctx(hctx);
> blk_mq_dispatch_rq_list(hctx, &rq_list);
What if we dispatched nothing on this hardware queue, and it currently
doesn't have any IO pending?
--
Jens Axboe
