On 05/17/2011 11:33 AM, Emmanuel Kasper wrote: > Hello > On a relatively busy xen server, running 10 VM, I noticed soft lock > coming regularly, around 06:25. > > > kern.log.2.gz:May 2 06:27:15 vaduz kernel: [10156409.027744] INFO: task > dpkg-query:24275 blocked for more than 120 seconds. > kern.log.2.gz:May 4 06:27:13 vaduz kernel: [10329259.982553] INFO: task > locate:6752 blocked for more than 120 seconds. > syslog.6.gz:May 12 06:27:17 vaduz kernel: [11020672.410138] INFO: task > update-dlocated:9078 blocked for more than 120 seconds. > syslog.7.gz:May 11 06:27:22 vaduz kernel: [10934249.078237] INFO: task > dlocate:15949 blocked for more than 120 seconds. > syslog.7.gz:May 11 06:27:28 vaduz kernel: [10934255.518954] INFO: task > kjournald:1297 blocked for more than 120 seconds. > syslog.7.gz:May 11 06:27:45 vaduz kernel: [10934272.704136] INFO: task > pdflush:244 blocked for more than 120 seconds. > > I guess every debian sysadmin around here will recognize the time at > which the daily crontab jobs :) > > Am I right to think here that my server is simply starving for I/O ? I > am thinking of split cron jobs out between 5:00 and 7:00, would that be > the right thing to do ? A lot of people is suffering this bug and still is unknown where exactly is the problem. For me started to happen with the upgrade to Squeeze. I workarounded it downgrading the kernel to lenny's one. It will be very useful that you report it on the bugzilla's kernel. The bug number is the following: https://bugzilla.kernel.org/show_bug.cgi?id=18632 If you know how to reproduce it or when will it happen please do the following when it is happening (as root) echo t >/proc/sysrq-trigger As a trick you can left the following dirty loop on a screen waiting for it to happen: while sleep 5; do dmesg |grep -q 'blocked for more than 120 seconds' && echo t >/proc/sysrq-trigger && break; done And then a lot of info about the internal kernel status will be printed to /var/log/kern.log Upload that info with a brief description of what the system was doing when it happened among useful information about your system like filesystems in use, kind of cpu, modules loaded... > > BTW if I understand right this kernel log is an INFO message, so it > means the kernel will not kill the process ? Or will he ? > No, the kernel will not kill anything. Only is letting you know that a process was blocked for more than 120 seconds because the kernel was unable to give the process the slot for I/O that it was requesting.
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