Re: [PATCH 0/1] blame: remove unnecessary use of get_commit_info()

Derrick Stolee [off-list ref] writes:

On 2/16/2021 11:31 AM, Rafael Silva wrote:

quoted

Running Git PERF suite in linux.git, I've got a subtle performance
improvement for some runs:

	# git.328c109303 - compiled git from commit 328c109303
	# git.blame-patched - compiled git from commit 328c109303 + this patch
        Test                                          git.328c109303    git.blame-patched
        -------------------------------------------------------------------------------------
        blame --color-by-age kernel/fork.c            1.96(1.81+0.15)   1.95(1.80+0.14) -0.5%
        blame --color-by-age kernel/sys.c             1.67(1.53+0.13)   1.66(1.52+0.14) -0.6%
        blame --color-by-age mm/slab.c                2.16(2.00+0.16)   2.15(1.99+0.15) -0.5%
        blame --color-by-age lib/packing.c            0.20(0.14+0.05)   0.20(0.14+0.05) +0.0%
        blame --color-by-age drivers/cdrom/cdrom.c    1.62(1.46+0.15)   1.62(1.46+0.15) +0.0%
        blame --color-by-age crypto/crypto_engine.c   0.37(0.29+0.06)   0.36(0.28+0.06) -2.7%
        blame --color-by-age net/ipv4/ip_forward.c    1.49(1.35+0.13)   1.48(1.34+0.13) -0.7%

Have you updated the commit-graph with changed-path Bloom filters in
your copy of linux.git before running the perf tests? You might get
smaller numbers overall (both sides) but make the difference for this
patch be more pronounced:

	git commit-graph write --reachable --changed-paths

Thanks for pointing this out. I didn't updated the commit-graph in my
copy of linux.git when I ran the perf tests and indeed with the
commit-graph updated, the execution time is faster now.

Here's the results (best out of 3):

        # git.328c109303 - compiled git from commit 328c109303
        # git.blame-patched - compiled git from commit 328c109303 + this patch
        Test                                          git.328c109303   git.blame-patched
        ------------------------------------------------------------------------------------
        blame --color-by-age kernel/fork.c            1.13(0.96+0.17)  1.12(0.96+0.15) -0.9%
        blame --color-by-age kernel/sys.c             1.00(0.81+0.18)  0.98(0.81+0.15) -2.0%
        blame --color-by-age mm/slab.c                1.51(1.33+0.18)  1.49(1.31+0.17) -1.3%
        blame --color-by-age lib/packing.c            0.13(0.05+0.07)  0.12(0.04+0.07) -7.7%
        blame --color-by-age drivers/cdrom/cdrom.c    0.62(0.48+0.12)  0.61(0.48+0.12) -1.6%
        blame --color-by-age crypto/crypto_engine.c   0.16(0.08+0.08)  0.16(0.07+0.08) +0.0%
        blame --color-by-age net/ipv4/ip_forward.c    0.43(0.30+0.13)  0.42(0.29+0.11) -2.3%

For the "kernel/fork.c" example, there is around 1.7x improvement. The
percentage comparison is also bigger than it was before the commit-graph
file was updated with the changed paths Bloom Filter as you expected.

For the "net/ipv4/ip_forward.c" there a 3.4x improvements which I
believe is the biggest one in my tests.

-- 
Thanks
Rafael