With likely/unlikely profiling (see the recent patch [email protected] sent), on my not-so-busy-typical-development system it shows more than 80K misses and no hits. So I guess it makes sense to revert.
I don't know BIO code very well, but I hope this data is useful for the experts.
Signed-off-by: Hua Zhong <[email protected]>
diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c
index 1755c05..499da1c 100644
--- a/block/ll_rw_blk.c
+++ b/block/ll_rw_blk.c
@@ -1432,7 +1432,7 @@ static int ll_back_merge_fn(request_queu
}
if (unlikely(!bio_flagged(req->biotail, BIO_SEG_VALID)))
blk_recount_segments(q, req->biotail);
- if (unlikely(!bio_flagged(bio, BIO_SEG_VALID)))
+ if (likely(!bio_flagged(bio, BIO_SEG_VALID)))
blk_recount_segments(q, bio);
len = req->biotail->bi_hw_back_size + bio->bi_hw_front_size;
if (BIOVEC_VIRT_MERGEABLE(__BVEC_END(req->biotail), __BVEC_START(bio)) &&
-
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