Date: Mon, 20 Sep 2010 16:21:17 +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: <4C9789FD.5000008@freebsd.org> In-Reply-To: <alpine.BSF.2.00.1009200326330.44058@pragry.qngnvk.ybpny> References: <4C961009.6080609@freebsd.org> <4C96ED40.7070206@DataIX.net> <4C976F14.8000408@freebsd.org> <alpine.BSF.2.00.1009200326330.44058@pragry.qngnvk.ybpny>
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jhell wrote: > > On Mon, 20 Sep 2010 10:26, David Xu wrote: > In Message-Id: <4C976F14.8000408@freebsd.org> > >> 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. >> > > > Inspecting the output of sysctl -b kern.geom.confdot will give you what > you currently have configured in the system as disks and what not > through geom. If this seems to be bailing at that point, which is an > opaque MIB/OID which doesn't come up other than when you use the "-o" > switch to sysctl(1) then could you check your labels for your disks for > any weird characters in the labels ? > > ( sysctl -bo kern.geom ) > > Also does this have the same effect when run in a xterm, cons25 terminal ? > > And same for the above but with the C, *_COUNTRY.UTF-8 or your normal > locale ? > > ( env LANG=C sysctl kern.geom ) > > Looking at the output from mine there are quite a few unprintable > characters present. Maybe these are having an impact with one of your > labels. > > I redirect all output to a disk file, and it still needs 1 second to complete, this machine is dual-core pentium E5500, faster than previous one which is a dual-core AMD 5000+ machine, the 5000+ needs 2 seconds to complete. $/usr/bin/time sysctl -b kern.geom.confdot > sysctl_geom_confdot.txt 1.00 real 0.00 user 0.00 sys the file is here: http://people.freebsd.org/~davidxu/sysctl_geom_confdot.txt
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