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Date:      Fri, 20 Mar 2009 19:27:02 -0800
From:      Mel Flynn <mel.flynn+fbsd.questions@mailing.thruhere.net>
To:        freebsd-questions@freebsd.org
Cc:        RW <rwmaillists@googlemail.com>
Subject:   Re: speed in extracting rar files - unrar vs. 7z
Message-ID:  <200903201927.02238.mel.flynn+fbsd.questions@mailing.thruhere.net>
In-Reply-To: <20090321015549.18863f97@gumby.homeunix.com>
References:  <20090321015316.87f9531b.ghirai@ghirai.com> <20090321015549.18863f97@gumby.homeunix.com>

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On Friday 20 March 2009 17:55:49 RW wrote:
> On Sat, 21 Mar 2009 01:53:16 +0200
>
> Ghirai <ghirai@ghirai.com> wrote:
> > The shareware WinRAR on windows seems to be better implemented (?), as
> > it uses both cores to the fullest, and as such the time needed to
> > extract stuff is a lot shorter.
>
> IIRC the unix version is portable C, but winrar has a lot of CPU
> specific optimizations.

Among which, being single threaded on unix:
% ldd /usr/local/bin/unrar
/usr/local/bin/unrar:
        libstdc++.so.6 => /usr/lib/libstdc++.so.6 (0x280ad000)
        libm.so.5 => /lib/libm.so.5 (0x281a1000)
        libgcc_s.so.1 => /lib/libgcc_s.so.1 (0x281bb000)
        libc.so.7 => /lib/libc.so.7 (0x281c6000)

Since disk can read faster then the decompression, a threadpool would be able 
to use both CPU's for decompressing and speed things up. At least in theory, 
but certainly on large files with SATA disks.

I believe 7z uses bigger buffers, which would explain the marginal difference 
in runtime.
-- 
Mel




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