Date: Sat, 22 May 2004 09:46:11 +0200 From: "Poul-Henning Kamp" <phk@phk.freebsd.dk> To: "Kevin Oberman" <oberman@es.net> Cc: freebsd-current@freebsd.org Subject: Re: Disk performance under CURRENT Message-ID: <45922.1085211971@critter.freebsd.dk> In-Reply-To: Your message of "Fri, 21 May 2004 15:47:29 PDT." <20040521224729.680285D0A@ptavv.es.net>
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In message <20040521224729.680285D0A@ptavv.es.net>, "Kevin Oberman" writes: >I just ran test of disk writing performance under V4 (STABLE) and V5 >(CURRENT) and was surprised at the difference. > >The test was simple and not at all rigorous. Just a dd bs=256k >if=/dev/zero of=/dev/ad2. This is about the simplest way of dealing with >a disk. No file system or anything else. Just raw data to the device. > >Under STABLE, I get an average of 25 MB/sec to the disk. Under CURRENT, >it drops to 15 MB/sec. I did this because I had noted that it was now >taking over an hour to backup my system disk (40 GB) when it was only >taking 40 minutes when I was running V4.6. The STABLE system was built >yesterday. The CURRENT system last Sunday. > >Any idea why this is so much slower? It looks to me like it must be in >either geom or the disk driver. GEOM is slower than 4-stable in a degenerate case like this, but it sounds to me like there is something else involved here too. Have you removed WITNESS from your kernel ? -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence.
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