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From: Johannes Schindelin <Johannes.Schindelin@gmx.de>
To: Jeff King <peff@peff.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>, git@vger.kernel.org
Subject: pcre performance, was Re: git log filtering
Date: Wed, 7 Mar 2007 18:37:23 +0100 (CET)	[thread overview]
Message-ID: <Pine.LNX.4.63.0703071807250.22628@wbgn013.biozentrum.uni-wuerzburg.de> (raw)
In-Reply-To: <20070208061654.GA8813@coredump.intra.peff.net>

Hi,

On Thu, 8 Feb 2007, Jeff King wrote:

> In every case there, pcre has either comparable performance, or simply 
> blows away glibc.

So I tested this against external grep. For completeness' sake, I tested 
these against each other: GNU regex-0.12, Git _without_ external grep 
(relies on glibc's regex), Git _with_ external grep ("original"), pcre, 
and for good measure, pcre with NO_MMAP=1 (to test if disk access is the 
problem).

Here are the numbers:

grep-gnu-regex:

21.41user 1.08system 0:22.52elapsed 99%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (0major+7210minor)pagefaults 0swaps
21.40user 1.06system 0:22.47elapsed 99%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (0major+7209minor)pagefaults 0swaps
21.61user 1.06system 0:22.68elapsed 99%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (0major+7209minor)pagefaults 0swaps
21.30user 1.10system 0:22.48elapsed 99%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (0major+7210minor)pagefaults 0swaps
21.30user 1.08system 0:22.43elapsed 99%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (0major+7209minor)pagefaults 0swaps

grep-no-external-grep:

6.98user 1.17system 0:08.16elapsed 99%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (0major+7120minor)pagefaults 0swaps
7.07user 1.16system 0:08.27elapsed 99%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (0major+7121minor)pagefaults 0swaps
6.98user 1.12system 0:08.11elapsed 100%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (0major+7121minor)pagefaults 0swaps
7.00user 1.18system 0:08.20elapsed 99%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (0major+7121minor)pagefaults 0swaps

grep-original:

0.82user 1.15system 0:01.97elapsed 100%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (0major+7090minor)pagefaults 0swaps
0.94user 1.03system 0:01.97elapsed 99%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (0major+7099minor)pagefaults 0swaps
0.89user 1.07system 0:01.96elapsed 100%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (0major+7092minor)pagefaults 0swaps
0.81user 1.15system 0:01.97elapsed 99%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (0major+7092minor)pagefaults 0swaps

grep-pcre:

4.04user 1.18system 0:05.24elapsed 99%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (0major+7205minor)pagefaults 0swaps
4.16user 1.08system 0:05.25elapsed 99%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (0major+7206minor)pagefaults 0swaps
4.24user 0.98system 0:05.23elapsed 99%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (0major+7206minor)pagefaults 0swaps
4.08user 1.14system 0:05.23elapsed 99%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (0major+7206minor)pagefaults 0swaps

grep-pcre-no-mmap:

4.15user 1.07system 0:05.22elapsed 99%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (0major+7210minor)pagefaults 0swaps
4.01user 1.14system 0:05.17elapsed 99%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (0major+7209minor)pagefaults 0swaps
3.94user 1.18system 0:05.14elapsed 99%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (0major+7210minor)pagefaults 0swaps
4.11user 1.06system 0:05.18elapsed 99%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (0major+7210minor)pagefaults 0swaps

BTW this was "git grep Lin.*valds" on linux-2.6, just updated.

The first test was run 5 times instead of 4 to make sure it is hot cache. 
This is on a dual 1.2GHz 2GB machine.

I cannot really say anything about the pagefaults, so I'll leave that to 
the wizards.

Result: external grep wins hands-down. GNU regex loses hands-down. pcre 
seems to be better than glibc's regex engine, and gains ever so slightly 
when using NO_MMAP.

I ran the same test on a 1GHz 256MB machine which is overloaded, and in 
that case, GNU regex is still worst (~55 sec), while glibc and pcre are 
equal (glibc slightly slower with ~35 sec, pcre ~34 sec), and external 
grep wins (~29 sec). Of course, this is io-bound, but it shows that pcre 
uses more memory than glibc.

Ciao,
Dscho

  parent reply	other threads:[~2007-03-07 17:38 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-02-07 16:41 git log filtering Don Zickus
2007-02-07 16:55 ` Jakub Narebski
2007-02-07 17:01 ` Uwe Kleine-König
2007-02-07 17:12   ` Johannes Schindelin
2007-02-07 17:12 ` Linus Torvalds
2007-02-07 17:25   ` Johannes Schindelin
     [not found]     ` <7v64ad7l12.fsf@assigned-by-dhcp.cox.net>
2007-02-07 21:03       ` Linus Torvalds
2007-02-07 21:09         ` Junio C Hamano
2007-02-07 21:53           ` Linus Torvalds
2007-02-08  6:16             ` Jeff King
2007-02-08 18:06               ` Johannes Schindelin
2007-02-08 22:33                 ` Jeff King
2007-02-09  0:18                   ` Johannes Schindelin
2007-02-09  0:23                     ` Shawn O. Pearce
2007-02-09  0:45                       ` Johannes Schindelin
2007-02-09 10:15                       ` Sergey Vlasov
2007-02-09  1:59                     ` Jeff King
2007-02-09 13:13                       ` Johannes Schindelin
2007-02-09 13:22                         ` Jeff King
2007-02-09 15:02                           ` Johannes Schindelin
2007-03-07 17:37               ` Johannes Schindelin [this message]
2007-03-07 18:03                 ` pcre performance, was " Paolo Bonzini
2007-02-08  1:59         ` Horst H. von Brand
2007-02-07 18:16   ` Linus Torvalds
2007-02-07 19:49     ` Fix "git log -z" behaviour Linus Torvalds
2007-02-07 19:55       ` Junio C Hamano
2007-02-07 22:53       ` Don Zickus
2007-02-07 23:05         ` Linus Torvalds
2007-02-08 22:34       ` Junio C Hamano
2007-02-10  7:32         ` Junio C Hamano
2007-02-10  9:36           ` Junio C Hamano
2007-02-10 17:09             ` Linus Torvalds
2007-02-07 18:19   ` git log filtering Don Zickus
2007-02-07 18:27     ` Linus Torvalds

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