[gpfsug-discuss] strange waiters + filesystem deadlock
Aaron Knister
aaron.s.knister at nasa.gov
Fri Mar 24 17:32:26 GMT 2017
heh, yep we're on sles :)
here's a screenshot of the fs manager from the deadlocked filesystem. I
don't think there's an nsd server or manager node that's running full
throttle across all cpus. There is one that's got relatively high CPU
utilization though (300-400%). I'll send a screenshot of it in a sec.
no zimon yet but we do have other tools to see cpu utilization.
-Aaron
On 3/24/17 1:22 PM, Sven Oehme wrote:
> you must be on sles as this segfaults only on sles to my knowledge :-)
>
> i am looking for a NSD or manager node in your cluster that runs at 100%
> cpu usage.
>
> do you have zimon deployed to look at cpu utilization across your nodes ?
>
> sven
>
>
>
> On Fri, Mar 24, 2017 at 10:08 AM Aaron Knister <aaron.s.knister at nasa.gov
> <mailto:aaron.s.knister at nasa.gov>> wrote:
>
> Hi Sven,
>
> Which NSD server should I run top on, the fs manager? If so the CPU load
> is about 155%. I'm working on perf top but not off to a great start...
>
> # perf top
> PerfTop: 1095 irqs/sec kernel:61.9% exact: 0.0% [1000Hz
> cycles], (all, 28 CPUs)
> ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
> Segmentation fault
>
> -Aaron
>
> On 3/24/17 1:04 PM, Sven Oehme wrote:
> > while this is happening run top and see if there is very high cpu
> > utilization at this time on the NSD Server.
> >
> > if there is , run perf top (you might need to install perf command) and
> > see if the top cpu contender is a spinlock . if so send a screenshot of
> > perf top as i may know what that is and how to fix.
> >
> > sven
> >
> >
> > On Fri, Mar 24, 2017 at 9:43 AM Aaron Knister <aaron.s.knister at nasa.gov <mailto:aaron.s.knister at nasa.gov>
> > <mailto:aaron.s.knister at nasa.gov <mailto:aaron.s.knister at nasa.gov>>> wrote:
> >
> > Since yesterday morning we've noticed some deadlocks on one of our
> > filesystems that seem to be triggered by writing to it. The waiters on
> > the clients look like this:
> >
> > 0x19450B0 ( 6730) waiting 2063.294589599 seconds, SyncHandlerThread:
> > on ThCond 0x1802585CB10 (0xFFFFC9002585CB10) (InodeFlushCondVar), reason
> > 'waiting for the flush flag to commit metadata'
> > 0x7FFFDA65E200 ( 22850) waiting 0.000246257 seconds,
> > AllocReduceHelperThread: on ThCond 0x7FFFDAC7FE28 (0x7FFFDAC7FE28)
> > (MsgRecordCondvar), reason 'RPC wait' for allocMsgTypeRelinquishRegion
> > on node 10.1.52.33 <c0n3271>
> > 0x197EE70 ( 6776) waiting 0.000198354 seconds,
> > FileBlockWriteFetchHandlerThread: on ThCond 0x7FFFF00CD598
> > (0x7FFFF00CD598) (MsgRecordCondvar), reason 'RPC wait' for
> > allocMsgTypeRequestRegion on node 10.1.52.33 <c0n3271>
> >
> > (10.1.52.33/c0n3271 <http://10.1.52.33/c0n3271>
> <http://10.1.52.33/c0n3271> is the fs manager
> > for the filesystem in question)
> >
> > there's a single process running on this node writing to the filesystem
> > in question (well, trying to write, it's been blocked doing nothing for
> > half an hour now). There are ~10 other client nodes in this situation
> > right now. We had many more last night before the problem seemed to
> > disappear in the early hours of the morning and now its back.
> >
> > Waiters on the fs manager look like this. While the individual waiter is
> > short it's a near constant stream:
> >
> > 0x7FFF60003540 ( 8269) waiting 0.001151588 seconds, Msg handler
> > allocMsgTypeRequestRegion: on ThMutex 0x1802163A2E0 (0xFFFFC9002163A2E0)
> > (AllocManagerMutex)
> > 0x7FFF601C8860 ( 20606) waiting 0.001115712 seconds, Msg handler
> > allocMsgTypeRelinquishRegion: on ThMutex 0x1802163A2E0
> > (0xFFFFC9002163A2E0) (AllocManagerMutex)
> > 0x7FFF91C10080 ( 14723) waiting 0.000959649 seconds, Msg handler
> > allocMsgTypeRequestRegion: on ThMutex 0x1802163A2E0 (0xFFFFC9002163A2E0)
> > (AllocManagerMutex)
> > 0x7FFFB03C2910 ( 12636) waiting 0.000769611 seconds, Msg handler
> > allocMsgTypeRequestRegion: on ThMutex 0x1802163A2E0 (0xFFFFC9002163A2E0)
> > (AllocManagerMutex)
> > 0x7FFF8C092850 ( 18215) waiting 0.000682275 seconds, Msg handler
> > allocMsgTypeRelinquishRegion: on ThMutex 0x1802163A2E0
> > (0xFFFFC9002163A2E0) (AllocManagerMutex)
> > 0x7FFF9423F730 ( 12652) waiting 0.000641915 seconds, Msg handler
> > allocMsgTypeRequestRegion: on ThMutex 0x1802163A2E0 (0xFFFFC9002163A2E0)
> > (AllocManagerMutex)
> > 0x7FFF9422D770 ( 12625) waiting 0.000494256 seconds, Msg handler
> > allocMsgTypeRequestRegion: on ThMutex 0x1802163A2E0 (0xFFFFC9002163A2E0)
> > (AllocManagerMutex)
> > 0x7FFF9423E310 ( 12651) waiting 0.000437760 seconds, Msg handler
> > allocMsgTypeRelinquishRegion: on ThMutex 0x1802163A2E0
> > (0xFFFFC9002163A2E0) (AllocManagerMutex)
> >
> > I don't know if this data point is useful but both yesterday and today
> > the metadata NSDs for this filesystem have had a constant aggregate
> > stream of 25MB/s 4kop/s reads during each episode (very low latency
> > though so I don't believe the storage is a bottleneck here). Writes are
> > only a few hundred ops and didn't strike me as odd.
> >
> > I have a PMR open for this but I'm curious if folks have seen this in
> > the wild and what it might mean.
> >
> > -Aaron
> >
> > --
> > Aaron Knister
> > NASA Center for Climate Simulation (Code 606.2)
> > Goddard Space Flight Center
> > (301) 286-2776 <tel:(301)%20286-2776> <tel:(301)%20286-2776>
> > _______________________________________________
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> >
> >
> >
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> >
>
> --
> Aaron Knister
> NASA Center for Climate Simulation (Code 606.2)
> Goddard Space Flight Center
> (301) 286-2776 <tel:(301)%20286-2776>
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--
Aaron Knister
NASA Center for Climate Simulation (Code 606.2)
Goddard Space Flight Center
(301) 286-2776
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