On Tue, Jul 03, 2012 at 02:35:28PM +0200, Andreas Heinlein wrote: > On 02.07.2012 21:07, Jeff Layton wrote: > >On Mon, 02 Jul 2012 11:43:48 +0200 > >Andreas Heinlein <aheinlein@xxxxxxx> wrote: > > > >>Hello, > >> > >>we have a strange NFS problem with a newly setup Linux server, and I > >>hope someone here can help. > >> > >>The symptom is that, slowly over time (speaking of several days up to 2 > >>weeks), the kernel nfsd processes/threads consume more and more CPU > >>until the system finally becomes unresponsive. We recorded system > >>activity with sar, which shows that CPU (system) usage slowly rises > >>after reboot from about 1% to nearly 100% over the course of several > >>days. Load averages stay around 0.1-0.3 until 100% are reached, up to > >>this point the problem is almost not noticable from the clients. Then > >>load averages climb up to 30.0; at this point the system becomes more or > >>less unusable and has to be restarted. 'top' output shows the CPU usage > >>evenly distributed across all nfsd threads. > >> > >>The system is a fairly recent, though entry level server with a Core i3 > >>and 4G RAM, hosting the home directories for about 15-20 clients. CPU > >>activity does not drop at night, when no clients are connected. It is > >>running Debian 6.0 with linux 3.2.0 (from the backports repository), > >>with nfs-utils 1.2.5 (also from the backports repository). I suspect > >>that these backports might be the culprit, but since we need this kernel > >>for other purposes, and I cannot reboot that machine during office > >>hours, I'd rather not try going back to the official Debian kernel > >>without good reasons. If there are known problems, I'd give it a try. > >> > >Find the pid of one of the nfsd threads that's spinning, then get a > >stack trace from it: > > > > # cat /proc/<pidofnfsd>/stack > > > >...that should give us some idea of what it's doing. > > > >-- > >Jeff Layton <jlayton@xxxxxxxxxx> > >-- > >To unsubscribe from this list: send the line "unsubscribe linux-nfs" in > >the body of a message to majordomo@xxxxxxxxxxxxxxx > >More majordomo info at http://vger.kernel.org/majordomo-info.html > Hello, > > I've run into the problem again, and did a 'watch cat > /proc/<pidofnfsd>/stack'. It actually seems to be doing something, > because the stack trace changes every now and then, but mostly looks > like > > [<c1038be2>] try_to_wake_up+0x144/0x14d > [<c1045d26>] lock_timer_base+0x19/0x34 > [<c10462fd>] __mod_timer+0x10c/0x116 > [<c1045d41>] process_timeout+0x0/0x5 > [<f858a243>] svc_recv+0x2e2/0x698 [sunrpc] > [<c1038beb>] default_wake_function+0x0/0x8 > [<f8640748>] nfsd+0x90/0x108 [nfsd] > [<f86406b8>] nfsd+0x0/0x108 [nfsd] > [<c105176b>] kthread+0x63/0x68 > [<c1051708>] kthread+0x0/0x68 > [<c12dadbe>] kernel_thread_helper+0x6/0x10 > [<ffffffff>] 0xffffffff > > Meanwhile, I've found a quite recent thread on this list named "3.0+ > NFS issues", and within two links to Ubuntu bug reports > (https://bugs.launchpad.net/ubuntu/+source/nfs-utils/+bug/879334 and > https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1006446) and There are a number of problems reported here, and it's not clear that they're the same. > again to a kernel bug > (https://bugzilla.kernel.org/show_bug.cgi?id=40912), all suggesting That one appears to be only reproduceable on dmcrypt with the nfsd threads reniced. > that this is indeed a kernel 3.0 problem. > > So I will try going back to 2.6.32 and hope this issue gets fixed soon. I don't know enough to be confident of that yet. > Thanks for your help! If you have the chance to test any intermediate kernels that might also give us some useful data points. --b. -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
