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

[Rafael Silva <rafaeloliveira.cs@gmail.com>]

Derrick Stolee <stolee@gmail.com> writes:

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