Date: Tue, 30 Aug 2005 18:55:05 -0700 (PDT) From: Don Lewis <truckman@FreeBSD.org> To: doconnor@gsoft.com.au Cc: freebsd-current@FreeBSD.org, kabaev@gmail.com Subject: Re: Odd performance problem (hitching) Message-ID: <200508310155.j7V1t57O016802@gw.catspoiler.org> In-Reply-To: <200508311045.56657.doconnor@gsoft.com.au>
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On 31 Aug, Daniel O'Connor wrote: > On Tuesday 30 August 2005 17:50, Daniel O'Connor wrote: >> > You might try significantly decreasing MAXVNODES_MAX in >> > sys/kern/vfs_subr.c and rebuilding your kernel. >> >> OK.. >> I'll try timing when the drop outs happen :) > > Hmm they appear to be every 10 seconds on the dot. Hmn, I wonder what runs every 10 seconds ... > I haven't changed any syncer delay stuff either.. > kern.filedelay: 30 > kern.dirdelay: 29 > kern.metadelay: 28 Those won't make any difference. They govern how many slots behind in the worklist that items of various types get inserted. The syncer wakes up once per second, processes all the items in a worklist slot, then goes back to sleep. The syncer vnode for each file system gets inserted when the file system is mounted and stays in the same slot, so the ugly FOREACH loop I mentioned earlier gets executed once each time the entire worklist is scanned, and since the worklist has 32 slots, the problem should only occur once every 32 seconds if you have one file system that has hogged most of the vnodes. If there are multiple file systems, the syncer vnodes will inserted at various power of two locations in the list, but I don't see a way to get activity spaced at ten second intervals. > Still using SCHED_4BSD too. >
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