Date: Mon, 20 Sep 2010 14:26:28 +0000 From: David Xu <davidxu@freebsd.org> To: jhell <jhell@DataIX.net> Cc: freebsd-current@freebsd.org Subject: Re: sysctl -a is slow Message-ID: <4C976F14.8000408@freebsd.org> In-Reply-To: <4C96ED40.7070206@DataIX.net> References: <4C961009.6080609@freebsd.org> <4C96ED40.7070206@DataIX.net>
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jhell wrote: > On 09/19/2010 09:28, David Xu wrote: >> just typed sysctl -a on keyboard, and found it is slow, sometimes >> it has been stuck for a few seconds, further studied,I found it is >> stucked at sysctl kern.geom: >> >> %/usr/bin/time sysctl -a kern.geom >> kern.geom.collectstats: 1 >> kern.geom.debugflags: 0 >> kern.geom.label.debug: 0 >> kern.geom.label.ext2fs.enable: 1 >> kern.geom.label.iso9660.enable: 1 >> kern.geom.label.msdosfs.enable: 1 >> kern.geom.label.ntfs.enable: 1 >> kern.geom.label.reiserfs.enable: 1 >> kern.geom.label.ufs.enable: 1 >> kern.geom.label.ufsid.enable: 1 >> kern.geom.label.gptid.enable: 1 >> kern.geom.label.gpt.enable: 1 >> 2.01 real 0.00 user 0.00 sys >> >> it seems it needs more than 2 seconds to complete. >> > > A ktrace(1) and a kdump(1) of the resulting ktrace.out file would > probably help here along with uname -a. Ive seen this happen once before > but do not recall what caused it. > > > Regards & good luck, > Result is dumped here. http://people.freebsd.org/~davidxu/sysctl_slow.txt I think the culprit is sysctl kern.geom.confdot, which does not appear in normal output, until I check the kdump result. I tried five times, and it was blocked three times.
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