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SubjectRe: [PATCH] fs/buffer.c: make bh_lru_install() more efficient
On Thu, Dec 29, 2016 at 01:34:45PM -0600, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@google.com>
>
> 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.
>
> Signed-off-by: Eric Biggers <ebiggers@google.com>

Ping? Al, do you have any interest in taking this patch?

- Eric

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