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bug#17229: [PATCH 2/2] grep: speed-up by using memchr() in Boyer-Moore s
From: |
Norihiro Tanaka |
Subject: |
bug#17229: [PATCH 2/2] grep: speed-up by using memchr() in Boyer-Moore searching |
Date: |
Thu, 10 Apr 2014 20:37:45 +0900 |
Hi Paul,
Hi Paul,
Thanks for the review for the patch.
> What benchmark did you use to time this?
I measured below.
$ yes jjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjj | head -10000000 >k
Before:
$ time -p env LANG=C src/grep jk k
real 1.53
user 1.21
sys 0.31
After:
$ time -p env LANG=C src/grep jk k
real 0.33
user 0.03
sys 0.29
> Is there some other patch that establishes this variable, a patch that
> is a prerequisite for this one?
The patch requires below.
bug#17230
[PATCH 1/2] grep: may also use Boyer-Moore algorithm for case-insensitive
matching
> What is delta1? It's mentioned in a comment but not in the code.
It means `d1' in kwset.c:bmexec.
> It'd be simpler to use memchr on all platforms;
> is there a major performance downside to that?
Yes. As far as I was confirmed, it's slow in HP-UX on Itanium and
Solaris on SPARC. I think that that it depends on the implementation of
memchr() and the rate of the increment instruction for the `add'
instruction on the platform.
Norihiro
- bug#17229: [PATCH 2/2] grep: speed-up by using memchr() in Boyer-Moore searching, Norihiro Tanaka, 2014/04/09
- bug#17229: [PATCH 2/2] grep: speed-up by using memchr() in Boyer-Moore searching, Paul Eggert, 2014/04/09
- bug#17229: [PATCH 2/2] grep: speed-up by using memchr() in Boyer-Moore searching,
Norihiro Tanaka <=
- bug#17229: [PATCH 2/2] grep: speed-up by using memchr() in Boyer-Moore searching, Paul Eggert, 2014/04/10
- bug#17229: [PATCH 2/2] grep: speed-up by using memchr() in Boyer-Moore searching, Eric Blake, 2014/04/10
- bug#17229: [PATCH 2/2] grep: speed-up by using memchr() in Boyer-Moore searching, Norihiro Tanaka, 2014/04/10
- bug#17229: [PATCH 2/2] grep: speed-up by using memchr() in Boyer-Moore searching, Norihiro Tanaka, 2014/04/10
- bug#17229: [PATCH 2/2] grep: speed-up by using memchr() in Boyer-Moore searching, Paul Eggert, 2014/04/23
- bug#17229: [PATCH 2/2] grep: speed-up by using memchr() in Boyer-Moore searching, Norihiro Tanaka, 2014/04/23
- bug#17229: [PATCH 2/2] grep: speed-up by using memchr() in Boyer-Moore searching, Paul Eggert, 2014/04/24
- bug#17229: [PATCH 2/2] grep: speed-up by using memchr() in Boyer-Moore searching, Norihiro Tanaka, 2014/04/25
- bug#17229: [PATCH 2/2] grep: speed-up by using memchr() in Boyer-Moore searching, Norihiro Tanaka, 2014/04/25
- bug#17229: [PATCH 2/2] grep: speed-up by using memchr() in Boyer-Moore searching, Eric Blake, 2014/04/25