Hi Jeff,
On Thu, Oct 15, 2015 at 11:26 PM, Jeff Moyer <jmo...@redhat.com> wrote:
> Ming Lei <ming....@canonical.com> writes:
>
>> Most of times, flush plug should be the hottest I/O path,
>> so mark ctx as pending after all requests in the list are
>> inserted.
>
> Hi, Ming,
>
> Did you see some performance gain from this?
Not done the test yet, but I think it is the correct thing to do because
the flag can be cleared quite frequently from other CPUs, and the numberof
marking pending can be decreased to ~1/16 of previous one.
>
> -Jeff
>
>>
>> Signed-off-by: Ming Lei <ming....@canonical.com>
>> ---
>> block/blk-mq.c | 18 +++++++++++++-----
>> 1 file changed, 13 insertions(+), 5 deletions(-)
>>
>> diff --git a/block/blk-mq.c b/block/blk-mq.c
>> index deb5f4c..1c943b9 100644
>> --- a/block/blk-mq.c
>> +++ b/block/blk-mq.c
>> @@ -993,18 +993,25 @@ void blk_mq_delay_queue(struct blk_mq_hw_ctx *hctx,
>> unsigned long msecs)
>> }
>> EXPORT_SYMBOL(blk_mq_delay_queue);
>>
>> -static void __blk_mq_insert_request(struct blk_mq_hw_ctx *hctx,
>> - struct request *rq, bool at_head)
>> +static inline void __blk_mq_insert_req_list(struct blk_mq_hw_ctx *hctx,
>> + struct blk_mq_ctx *ctx,
>> + struct request *rq,
>> + bool at_head)
>> {
>> - struct blk_mq_ctx *ctx = rq->mq_ctx;
>> -
>> trace_block_rq_insert(hctx->queue, rq);
>>
>> if (at_head)
>> list_add(&rq->queuelist, &ctx->rq_list);
>> else
>> list_add_tail(&rq->queuelist, &ctx->rq_list);
>> +}
>> +
>> +static void __blk_mq_insert_request(struct blk_mq_hw_ctx *hctx,
>> + struct request *rq, bool at_head)
>> +{
>> + struct blk_mq_ctx *ctx = rq->mq_ctx;
>>
>> + __blk_mq_insert_req_list(hctx, ctx, rq, at_head);
>> blk_mq_hctx_mark_pending(hctx, ctx);
>> }
>>
>> @@ -1060,8 +1067,9 @@ static void blk_mq_insert_requests(struct
>> request_queue *q,
>> rq = list_first_entry(list, struct request, queuelist);
>> list_del_init(&rq->queuelist);
>> rq->mq_ctx = ctx;
>> - __blk_mq_insert_request(hctx, rq, false);
>> + __blk_mq_insert_req_list(hctx, ctx, rq, false);
>> }
>> + blk_mq_hctx_mark_pending(hctx, ctx);
>> spin_unlock(&ctx->lock);
>>
>> blk_mq_run_hw_queue(hctx, from_schedule);
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majord...@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at http://www.tux.org/lkml/
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
