Commit 080ff351 authored Dec 08, 2014 by Jens Axboe

blk-mq: re-check for available tags after running the hardware queue



If we run out of tags and have to sleep, we run the hardware queue
to kick pending IO into gear. During that run, we may have completed
requests, so re-check if we have free tags before going to sleep.

Signed-off-by: Jens Axboe <axboe@fb.com>

parent b3223207

block/blk-mq-tag.c

+8 −0

Original line number	Diff line number	Diff line
		@@ -261,6 +261,14 @@ static int bt_get(struct blk_mq_alloc_data *data,
		*/
		blk_mq_run_hw_queue(hctx, false);

		/*
		* Retry tag allocation after running the hardware queue,
		* as running the queue may also have found completions.
		*/
		tag = __bt_get(hctx, bt, last_tag);
		if (tag != -1)
		break;

		blk_mq_put_ctx(data->ctx);

		io_schedule();

Admin message