Re: [PATCH] blk-mq: run hw queue asynchronously in blk_mq_start_hw_queues
From: Jens Axboe
Date: Tue Jun 24 2014 - 23:01:09 EST
On 2014-06-24 20:42, Ming Lei wrote:
On Tue, Jun 24, 2014 at 10:53 PM, Ming Lei <tom.leiming@xxxxxxxxx> wrote:
From API view, it isn't good to run all hw queues synchronously
in one context, since it isn't correct for multi hw queue case.
So this patch adds 'async' parameter to blk_mq_start_hw_queue(),
and make blk_mq_start_hw_queues() to run hw queues asynchronously
at default.
BTW, without the change, it is easy to trigger the WARN_ON() in
__blk_mq_run_hw_queue().
Why not just have it call blk_mq_run_hw_queue()? Pass in async == false,
but let the cpumask logic sort out if we need to force an async run.
--
Jens Axboe
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 0ef2dc7f01bf..ad69ef657e85 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -878,7 +878,7 @@ void blk_mq_start_hw_queue(struct blk_mq_hw_ctx *hctx)
clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
preempt_disable();
- __blk_mq_run_hw_queue(hctx);
+ blk_mq_run_hw_queue(hctx, false);
preempt_enable();
}
EXPORT_SYMBOL(blk_mq_start_hw_queue);