Re: [GSoC] Git Blog 11

From: ZheNing Hu <adlternative@gmail.com>
To: Christian Couder <christian.couder@gmail.com>
Cc: Junio C Hamano <gitster@pobox.com>,
	Hariom verma <hariom18599@gmail.com>,
	Git List <git@vger.kernel.org>
Subject: Re: [GSoC] Git Blog 11
Date: Tue, 3 Aug 2021 10:49:18 +0800	[thread overview]
Message-ID: <CAOLTT8QDo1A4tRqU0w-yas8OxrHB6uQ_PECswUQtQ7yY2-iWgw@mail.gmail.com> (raw)
In-Reply-To: <CAOLTT8SaXqWF3AJssqudrDK-KZN3oESO7Xh0JTYB_=HR9L9sHg@mail.gmail.com>

ZheNing Hu <adlternative@gmail.com> 于2021年8月3日周二 上午10:37写道：
>
> Christian Couder <christian.couder@gmail.com> 于2021年8月2日周一 下午2:25写道：
> >
> > On Sun, Aug 1, 2021 at 8:45 AM ZheNing Hu <adlternative@gmail.com> wrote:
> >
> > > in some cases, this is the result of the performance test of
> > > `t/perf/p1006-cat-file.sh`:
> > >
> > > ```
> > > Test                                        HEAD~             HEAD
> > > ------------------------------------------------------------------------------------
> > > 1006.2: cat-file --batch-check              0.10(0.09+0.00)
> > > 0.11(0.10+0.00) +10.0%
> > > 1006.3: cat-file --batch-check with atoms   0.09(0.08+0.01)
> > > 0.09(0.06+0.03) +0.0%
> > > 1006.4: cat-file --batch                    0.62(0.58+0.04)
> > > 0.57(0.54+0.03) -8.1%
> > > 1006.5: cat-file --batch with atoms         0.63(0.60+0.02)
> > > 0.52(0.49+0.02) -17.5%
> > > ```
> > >
> > > We can see that the performance of `git cat-file --batch` has been a
> > > certain improvement!
> >
> > Yeah, sure -8.1% or -17.5% is really nice! But why +10.0% for
> > `cat-file --batch-check`?
> >
>
> I think it's not very important. Because our optimization is skipping
> parse_object_buffer(), git cat-file --batch-check will not set oi->contentp
> by default, parse_object_buffer() will not be executed, Therefore, we did
> not optimize `git cat-file --batch-check` at all. 10% may be small enough
> for git cat-file --batch-check. The noise of environment even will cover it...
>

By the way, its performance may still be worse than "upstream/master", but it
will be better than before optimization.

Test                                        HEAD~             this tree
------------------------------------------------------------------------------------
1006.2: cat-file --batch-check              0.10(0.09+0.01)
0.09(0.08+0.01) -10.0%
1006.3: cat-file --batch-check with atoms   0.09(0.07+0.02)
0.08(0.05+0.03) -11.1%
1006.4: cat-file --batch                    0.61(0.59+0.02)
0.53(0.51+0.02) -13.1%
1006.5: cat-file --batch with atoms         0.60(0.57+0.02)
0.52(0.49+0.03) -13.3%

Test                                        upstream/master   this
tree
------------------------------------------------------------------------------------
1006.2: cat-file --batch-check              0.08(0.07+0.01)
0.10(0.07+0.02) +25.0%
1006.3: cat-file --batch-check with atoms   0.06(0.05+0.01)
0.08(0.08+0.00) +33.3%
1006.4: cat-file --batch                    0.49(0.46+0.03)
0.53(0.50+0.03) +8.2%
1006.5: cat-file --batch with atoms         0.48(0.45+0.03)
0.51(0.48+0.02) +6.3%

Test                                        upstream/master   HEAD~
------------------------------------------------------------------------------------
1006.2: cat-file --batch-check              0.08(0.07+0.01)
0.10(0.07+0.03) +25.0%
1006.3: cat-file --batch-check with atoms   0.06(0.05+0.00)
0.08(0.08+0.00) +33.3%
1006.4: cat-file --batch                    0.48(0.46+0.02)
0.60(0.57+0.03) +25.0%
1006.5: cat-file --batch with atoms         0.47(0.44+0.03)
0.63(0.59+0.04) +34.0%

Thanks.
--
ZheNing Hu