ixgbe/NFS m_defrag() instrumentation
John Baldwin
jhb at freebsd.org
Tue Feb 11 19:49:55 UTC 2014
On Wednesday, February 05, 2014 12:27:15 am Garrett Wollman wrote:
> I instrumented calls to m_defrag() in ixgbe. As expected, it gets
> called *a lot* when NFS is running with the default read size of 64k.
> A simple benchmark (single-threaded sequential read of a 128 GB file
> which I didn't even run to completion) tells the tale:
>
> $ sysctl dev.ix.0.mbuf_defrag_attempted
> dev.ix.0.mbuf_defrag_attempted: 1737994
>
> (There's already a similar counter for m_defrag() failures, which made
> it easy to add this counter. Unfortunately, there is no analogous
> instrumentation in cxgbe so I couldn't do likewise for that NIC.)
Is this due to the other thread Rick has about TSO interacting with NFS?
Do these go away if you disable TSO on the interface?
--
John Baldwin
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