From: Joe Perches <joe@perches.com>
To: "Stefan Beller" <sbeller@google.com>,
"Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
Cc: git <git@vger.kernel.org>
Subject: Re: grep vs git grep performance?
Date: Thu, 26 Oct 2017 10:41:36 -0700 [thread overview]
Message-ID: <1509039696.11245.9.camel@perches.com> (raw)
In-Reply-To: <CAGZ79ka41NdzNxGAvtVW802088KydKkp3yHx=Z5q3Mc9GGa_+g@mail.gmail.com>
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
next prev parent reply other threads:[~2017-10-26 17:41 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 [this message]
2017-10-26 17:45 ` Stefan Beller
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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