Messages in this thread | | | Date | Thu, 04 Sep 2014 19:30:18 -0600 | From | Jens Axboe <> | Subject | Re: [PATCH 1/3] blk-mq: Cleanup blk_mq_tag_busy() and blk_mq_tag_idle() |
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On 09/04/2014 07:26 PM, Chuck Ebbert wrote: > On Wed, 03 Sep 2014 14:35:29 -0600 > Jens Axboe <axboe@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.
It's a common construct. Besides, if you find a flag-not-set check convoluted, then I hope you are not programming anything I use. That's a bit of a straw man, imho.
-- Jens Axboe
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