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SubjectRe: [PATCH] fs/buffer.c: make bh_lru_install() more efficient
On Sat, Mar 25, 2017 at 08:34:30PM -0700, Eric Biggers wrote:
> 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
IMO, It is great patch.
Could you please share your microbenchmark steps?
I wanna take a deep look at it.

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