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Eric Biggers authored
To install a buffer_head into the cpu's LRU queue, bh_lru_install() would construct a new copy of the queue and then memcpy it over the real queue. But it's easily possible to do the update in-place, which is faster and simpler. Some work can also be skipped if the buffer_head was already in the queue. As a microbenchmark I timed how long it takes to run sb_getblk() 10,000,000 times alternating between BH_LRU_SIZE + 1 blocks. Effectively, this benchmarks looking up buffer_heads that are in the page cache but not in the LRU: Before this patch: 1.758s After this patch: 1.653s This patch also removes about 350 bytes of compiled code (on x86_64), partly due to removal of the memcpy() which was being inlined+unrolled. Link: http://lkml.kernel.org/r/20161229193445.1913-1-ebiggers3@gmail.comSigned-off-by:
Eric Biggers <ebiggers@google.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Christoph Lameter <cl@linux.com> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
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