Date: Wed, 24 Aug 2005 23:00:23 +0200 From: JG <jarek@adeon.lublin.pl> To: Jonathan Noack <noackjr@alumni.rice.edu> Cc: freebsd-performance@freebsd.org Subject: Re[2]: slow tar performance on fbsd5 Message-ID: <1626642863.20050824230023@adeon.lublin.pl> In-Reply-To: <430CBC18.6040902@alumni.rice.edu> References: <1168719770.20050824183357@adeon.lublin.pl> <430CBC18.6040902@alumni.rice.edu>
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> Will noatime make a difference when unpacking a tar archive (assuming an > otherwise idle system, at least)? My understanding of atime is that it > might slow down the disk for later accesses due to atime writes, but > when creating files it shouldn't have any effect. Is that not correct? Yes, you're right. > Your other settings appear ok, but I'd turn off hyperthreading. Almost > every FreeBSD/HT test has shown that it reduces performance because the > scheduler is not HT-aware. When the system is relatively idle (single > dd running, for example), it might not pessimize things, but it will > most likely slow you down under load. HTT is a big performance hit for me, mainly for webserver. I've much worse diskinfo results without HTT, don't know why. Tar is upacking a bit longer with HTT disabled. > This sounds like you're running into the old "lemming syncer" problem. > There is currently some work on disk schedulers (even a Summer of Code > project), but it will most likely not make it into 5.x. Agrh.. Regards, Jarek
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