Re: [PATCH 4/9] blk-mq: only run hw queues for blk-mq

2017-09-01 Thread Johannes Thumshirn 
On Fri, Sep 01, 2017 at 08:33:40PM +0800, Ming Lei wrote:
> Given it is the only case that blk_mq_run_hw_queues() is run on
> !q->mq_ops now, I suggest to check q->mq_ops outside, otherwise
> it can be a bit overkill.

Fair enough,
Reviewed-by: Johannes Thumshirn 
-- 
Johannes Thumshirn  Storage
jthumsh...@suse.de+49 911 74053 689
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
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HRB 21284 (AG Nürnberg)
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Re: [PATCH 4/9] blk-mq: only run hw queues for blk-mq

2017-09-01 Thread Ming Lei 
On Fri, Sep 01, 2017 at 10:16:34AM +0200, Johannes Thumshirn wrote:
> Hi Ming,
> 
> On Fri, Sep 01, 2017 at 01:27:23AM +0800, Ming Lei wrote:
> > -   blk_mq_run_hw_queues(q, false);
> > +   if (q->mq_ops)
> > +   blk_mq_run_hw_queues(q, false);
> 
> What speaks against putting the if (q->mq_ops) directly into
> blk_mq_run_hw_queues() so we can't accidently call it from the sq path?
> 
> Just an idea, no hard preferences here.

Given it is the only case that blk_mq_run_hw_queues() is run on
!q->mq_ops now, I suggest to check q->mq_ops outside, otherwise
it can be a bit overkill.

-- 
Ming

Re: [PATCH 4/9] blk-mq: only run hw queues for blk-mq

2017-09-01 Thread Johannes Thumshirn 
Hi Ming,

On Fri, Sep 01, 2017 at 01:27:23AM +0800, Ming Lei wrote:
> - blk_mq_run_hw_queues(q, false);
> + if (q->mq_ops)
> + blk_mq_run_hw_queues(q, false);

What speaks against putting the if (q->mq_ops) directly into
blk_mq_run_hw_queues() so we can't accidently call it from the sq path?

Just an idea, no hard preferences here.

Byte,
Johannes

-- 
Johannes Thumshirn  Storage
jthumsh...@suse.de+49 911 74053 689
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: Felix Imendörffer, Jane Smithard, Graham Norton
HRB 21284 (AG Nürnberg)
Key fingerprint = EC38 9CAB C2C4 F25D 8600 D0D0 0393 969D 2D76 0850

[PATCH 4/9] blk-mq: only run hw queues for blk-mq

2017-08-31 Thread Ming Lei 
This patch just makes it explicitely.

Signed-off-by: Ming Lei 
---
 block/blk-mq.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 8cf1f7cbef2b..4c532d8612e1 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -125,7 +125,8 @@ void blk_freeze_queue_start(struct request_queue *q)
freeze_depth = atomic_inc_return(&q->mq_freeze_depth);
if (freeze_depth == 1) {
percpu_ref_kill(&q->q_usage_counter);
-   blk_mq_run_hw_queues(q, false);
+   if (q->mq_ops)
+   blk_mq_run_hw_queues(q, false);
}
 }
 EXPORT_SYMBOL_GPL(blk_freeze_queue_start);
-- 
2.9.5