Ming Lei <ming....@canonical.com> writes:
> The trace point is for tracing plug event of each request
> queue instead of each task, so we should check the request
> count in the plug list from current queue instead of
> current task.
If blk_queue_nomerges returns true, request_count won't be updated, so
you've essentially broken plugging for those queues.
Cheers,
Jeff
>
> Signed-off-by: Ming Lei <ming....@canonical.com>
> ---
> block/blk-mq.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/block/blk-mq.c b/block/blk-mq.c
> index d55d022..a5e33bc 100644
> --- a/block/blk-mq.c
> +++ b/block/blk-mq.c
> @@ -1377,7 +1377,7 @@ static void blk_sq_make_request(struct request_queue
> *q, struct bio *bio)
> plug = current->plug;
> if (plug) {
> blk_mq_bio_to_request(rq, bio);
> - if (list_empty(&plug->mq_list))
> + if (!request_count)
> trace_block_plug(q);
> else if (request_count >= BLK_MAX_REQUEST_COUNT) {
> blk_flush_plug_list(plug, false);
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