On Feb 12, 2007, at 7:52 AM, Robert Milkowski wrote:
Hello Roch,
Monday, February 12, 2007, 3:54:30 PM, you wrote:
RP> Duh!.
RP> Long sync (which delays the next sync) are also possible on
RP> a write intensive workloads. Throttling heavy writters, I
RP> think, is the key to fixing this.
Well, then maybe it's not the cause to our problems.
Nevertheless 60-90s for unlink() is just plain wrong especially when
you've got <10ms IOs to array, almost zero writes, plenty of CPU free,
etc.
Definitely something is wrong here.
Looks like spa_sync() via the txg_sync_thread thread is taking way
too long, which is causing new (NFS) requests to be delayed (such as
unlink).
Is this just a NFS server, or is there local activity as well?
A complete threadlist would be interesting, as would memory usage.
Have you increased the load on this machine? I have seen a similar
situation (new requests being blocked waiting for the sync thread to
finish), but that's only been when either 1) the hardware is broken
and taking too long or 2) the server is way overloaded.
eric
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