Date: Sat, 30 Jul 2005 07:44:50 +1000 From: Peter Jeremy <peterjeremy@optushome.com.au> To: Julian Elischer <julian@elischer.org> Cc: FreeBSD Current <freebsd-current@freebsd.org> Subject: Re: 6.0 VFS/VM over-runs. Was: Apparent strange disk behaviour in 6.0 Message-ID: <20050729214450.GB81215@server.vk2pj.dyndns.org> In-Reply-To: <42E94A88.4010603@elischer.org> References: <42E88135.30603@elischer.org> <42E88F2B.5000108@elischer.org> <20050728082844.GW46538@darkness.comp.waw.pl> <42E898A6.6010803@elischer.org> <20050728115251.GA20091@beatrix.daedalusnetworks.priv> <20050728135613.GD46538@darkness.comp.waw.pl> <42E93EE1.2090009@elischer.org> <42E94310.20806@samsco.org> <42E94A88.4010603@elischer.org>
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[CC list pruned] On Thu, Jul 28, 2005 at 02:13:44PM -0700, Julian Elischer wrote: >file data written to cache to await output to disk is allowed to grow to >the extent that running programs are swapped out. >(or at least paged out). I don't see this on 5.3 either. In multi-user mode (with lots of other processes sitting aroung idle) vmstat shows fr and sr sit at around 10,000/sec but there's no paging and a "ps -axl" afterwards shows everything mostly still resident. The active memory (avm) hardly changes but free memory drops from 233MB to 20MB over 8 seconds than oscillates between about 16MB and 30MB. Disk I/O remains at 35-40MB/sec (ie disk limited). This is an Athlon XP-1800 512MB RAM writing a 10GB file onto an ATA disk. PREEMPTION is enabled. Since Marc Olzheim reports it happens with 5-STABLE and Julian reports it doesn't happen on 5.4 and I can't reproduce it on 5.3, one option would seem to be that it was MFC'd to 5 at some point since 5.4 was branched. Unfortunately, a quick scan through the RELENG_5 commits doesn't reveal anything that might be relevant. The other possibility is that it's RAM size related. The vmstat output Julian posted demonstrating the problem was on a system with a fair bit of RAM, but his 5.4 system is presumably smaller and my system definitely is. -- Peter
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