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Date:      Thu, 31 Dec 2015 13:32:02 -0500
From:      "Jonathan T. Looney" <jtl@freebsd.org>
To:        Allan Jude <allanjude@freebsd.org>, Bruce Evans <brde@optusnet.com.au>
Cc:        <src-committers@freebsd.org>, <svn-src-all@freebsd.org>, <svn-src-head@freebsd.org>
Subject:   Re: svn commit: r292955 - head/lib/libmd
Message-ID:  <D2AADE36.4E8D4%jlooney@juniper.net>
In-Reply-To: <5684D606.3080609@freebsd.org>
References:  <201512301804.tBUI4oGp065466@repo.freebsd.org> <20151231115651.R995@besplex.bde.org> <20151231143314.Y1520@besplex.bde.org> <5684D606.3080609@freebsd.org>

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On 12/31/15, 2:15 AM, "Allan Jude" <allanjude@freebsd.org> wrote:

>It seems these problems also slow things down, a lot:
>
># time md5 /media/md5test/bigdata
>MD5 (/media/md5test/bigdata) = 6afad0bf5d8318093e943229be05be67
>4.310u 3.476s 0:07.79 99.8%     20+167k 0+0io 0pf+0w
># time env LD_PRELOAD=/usr/obj/media/svn/md5/head/tmp/lib/libmd.so
>/usr/obj/media/svn/md5/head/sbin/md5/md5 /media/md5test/bigdata
>MD5 (/media/md5test/bigdata) = 6afad0bf5d8318093e943229be05be67
>4.133u 0.354s 0:04.49 99.7%     20+167k 1+0io 0pf+0w
>
>(file is fully cached in ZFS ARC, dd reads it at 11GB/s)
>
>Will investigate more tomorrow.

md5 will be slower than dd due to the extra processing it needs to do to
generate the hash. I suspect that explains the difference you're seeing
between those utilities.

Jonathan





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