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List:       opensuse
Subject:    Re: [opensuse] Performance of "cut" and "uniq"
From:       Jeff Janes <jeff.janes () gmail ! com>
Date:       2012-04-30 20:28:24
Message-ID: CAMkU=1w0Sq0t1-saQkTZJXDa_rShqrNvrph-iP3bKWoSttk=jw () mail ! gmail ! com
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On Sat, Apr 28, 2012 at 12:24 PM, Philipp Thomas
<Philipp.Thomas2@gmx.net> wrote:
> On Fri, 27 Apr 2012 20:24:32 -0700, Jeff Janes <jeff.janes@gmail.com>
> wrote:
>
>>The difference in performance is erased by setting LANG=C (the default
>>is en_US.UTF-8), which change makes the installed binary much faster
>>but doesn't change the built-from-source binary performance.  See
>>examples below.
>
> That's to be expected. Many distributions (I know of at least Fedora
> and Arch Linux besides SUSE) use a patch that teaches the coreutils
> how to handle multibyte locales. The downside is that multibyte
> processing slows down the utils.

OK, thanks.  I think there might be a way to only suffer the slow down
if the delimiter is actually a wide character (sort, for example,
doesn't seem to be slowed down when the input happens to have no wide
characters), but I don't know how to go about doing that.  I'll
probably just set LANG=C in my login rc file and call it a day.

>
>>Is it a known issue that building from source lets the CPU safely take
>>advantage of short-cuts to make things faster even under UTF-8 that a
>>packaged binary cannot?  Or perhaps is there a bug in the
>>build-from-source that makes it faster, but somehow unsafe for UTF-8?
>
> Something's wrong if you get different results from a binary package
> vs. binaries built by building your owen rpm.
>
> If you do not use our spec file and the patches we supply it's no
> wonder you get faster binaries. So the real question is, how did you
> build the binaries precisely.

I built it from the instructions from INSTALL file that came in the
tarball put in /usr/src/packages/SOURCES by running zypper install -t
srcpackage coreutils.   So I guess I did the wrong thing there.

> If you built the package locally by using build, there should be no
> differences.

OK, thanks.  I haven't been able to get build to work for me yet, I'll
keep trying.

Thanks,

Jeff
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