On Wed, 03 Sep 2014 14:35:29 -0600
Jens Axboe <ax...@kernel.dk> wrote:
> On 09/03/2014 02:33 PM, Alexander Gordeev wrote:
<snip>
> > diff --git a/block/blk-mq-tag.h b/block/blk-mq-tag.h
> > index 6206ed1..795ec3f 100644
> > --- a/block/blk-mq-tag.h
> > +++ b/block/blk-mq-tag.h
> > @@ -66,23 +66,22 @@ enum {
> > BLK_MQ_TAG_MAX = BLK_MQ_TAG_FAIL - 1,
> > };
> >
> > -extern bool __blk_mq_tag_busy(struct blk_mq_hw_ctx *);
> > +extern void __blk_mq_tag_busy(struct blk_mq_hw_ctx *);
> > extern void __blk_mq_tag_idle(struct blk_mq_hw_ctx *);
> >
> > static inline bool blk_mq_tag_busy(struct blk_mq_hw_ctx *hctx)
> > {
> > - if (!(hctx->flags & BLK_MQ_F_TAG_SHARED))
> > - return false;
> > -
> > - return __blk_mq_tag_busy(hctx);
> > + if (hctx->flags & BLK_MQ_F_TAG_SHARED) {
> > + __blk_mq_tag_busy(hctx);
> > + return true;
> > + }
> > + return false;
> > }
>
> The normal/fast path here is the flag NOT being set, which is why it
> was coded that way to put the fast path inline.
>
> >
> > static inline void blk_mq_tag_idle(struct blk_mq_hw_ctx *hctx)
> > {
> > - if (!(hctx->flags & BLK_MQ_F_TAG_SHARED))
> > - return;
> > -
> > - __blk_mq_tag_idle(hctx);
> > + if (hctx->flags & BLK_MQ_F_TAG_SHARED)
> > + __blk_mq_tag_idle(hctx);
> > }
>
> Ditto
Shouldn't it just add unlikely() then? That way it's obvious what the
common case is, instead of relying on convoluted code.
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