On 09/21/10 00:01, David Xu wrote: > Lawrence Stewart wrote: >> On 09/21/10 02:21, David Xu wrote: >> >>> jhell wrote: >>> >>>> On Mon, 20 Sep 2010 10:26, David Xu wrote: >>>> In Message-Id: <4c976f14.8000...@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 >>> >> >> As an extra data point, running "/usr/bin/time sysctl -b >> kern.geom.confdot" repeatedly on my amd64 8.1-STABLE desktop varies >> between 0s and 2s. It reports 0 majority of the time but every 5 or so >> runs it'll stall for 1 or 2 seconds. So the problem isn't isolated to >> head. >> >> Cheers, >> Lawrence >> > > I happened to set kern.sched.preempt_thresh=200, so the kernel is more > aggressive > than default on thread preemption. it is easier than default to > reproduce the > problem, my desktop machine is idle, but it still stalls 1 or 2 > seconds on the sysctl.
heh, from /etc/sysctl.conf on the machine I tested with: # 4/9/2010 # should give more responsiveness on desktop suggested # by David Xu <davi...@freebsd.org> on freebsd-stable@ kern.sched.preempt_thresh=220 This machine is my primary kde4 desktop at home. Cheers, Lawrence _______________________________________________ freebsd-current@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-current To unsubscribe, send any mail to "freebsd-current-unsubscr...@freebsd.org"
