From: Stefan Beller <sbeller@google.com>
To: Joe Perches <joe@perches.com>
Cc: "Ævar Arnfjörð Bjarmason" <avarab@gmail.com>, git <git@vger.kernel.org>
Subject: Re: grep vs git grep performance?
Date: Thu, 26 Oct 2017 10:45:57 -0700 [thread overview]
Message-ID: <CAGZ79kYWPunzZ2u=MtCoCadxXu_4etEK5DYnhYXo+CgeHrXQwQ@mail.gmail.com> (raw)
In-Reply-To: <1509039696.11245.9.camel@perches.com>
On Thu, Oct 26, 2017 at 10:41 AM, Joe Perches <joe@perches.com> wrote:
> On Thu, 2017-10-26 at 09:58 -0700, Stefan Beller wrote:
>> + Avar who knows a thing about pcre (I assume the regex compilation
>> has impact on grep speed)
>>
>> On Thu, Oct 26, 2017 at 8:02 AM, Joe Perches <joe@perches.com> wrote:
>> > Comparing a cache warm git grep vs command line grep
>> > shows significant differences in cpu & wall clock.
>> >
>> > Any ideas how to improve this?
>> >
>> > $ time git grep "\bseq_.*%p\W" | wc -l
>> > 112
>> >
>> > real 0m4.271s
>> > user 0m15.520s
>> > sys 0m0.395s
>> >
>> > $ time grep -r --include=*.[ch] "\bseq_.*%p\W" * | wc -l
>> > 112
>> >
>> > real 0m1.164s
>> > user 0m0.847s
>> > sys 0m0.314s
>> >
>>
>> I wonder how much is algorithmic advantage vs coding/micro
>> optimization that we can do.
>
> As do I. I presume this is libpcre related.
>
> For instance, git grep performance is better than grep for:
>
> $ time git grep -w "seq_printf" -- "*.[ch]" | wc -l
> 8609
>
> real 0m0.301s
> user 0m0.548s
> sys 0m0.372s
>
> $ time grep -w -r --include=*.[ch] "seq_printf" * | wc -l
> 8609
>
> real 0m0.706s
> user 0m0.396s
> sys 0m0.309s
>
One important piece of information is what version of Git you are running,
$ git tag --contains origin/ab/pcre-v2
v2.14.0
...
(and the version of pcre, see the numbers)
https://git.kernel.org/pub/scm/git/git.git/commit/?id=94da9193a6eb8f1085d611c04ff8bbb4f5ae1e0a
next prev parent reply other threads:[~2017-10-26 17:46 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-26 15:02 grep vs git grep performance? Joe Perches
2017-10-26 15:11 ` Han-Wen Nienhuys
2017-10-26 15:55 ` Joe Perches
2017-10-26 16:13 ` SZEDER Gábor
2017-10-26 16:20 ` Joe Perches
2017-10-26 16:58 ` Stefan Beller
2017-10-26 17:41 ` Joe Perches
2017-10-26 17:45 ` Stefan Beller [this message]
2017-10-27 17:22 ` Joe Perches
2017-10-27 22:11 ` Ævar Arnfjörð Bjarmason
2017-10-27 23:22 ` Joe Perches
2017-10-28 7:45 ` Ævar Arnfjörð Bjarmason
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