Date: Wed, 5 Feb 2014 00:27:15 -0500 From: Garrett Wollman <wollman@freebsd.org> To: freebsd-net@freebsd.org Cc: rmacklem@freebsd.org Subject: ixgbe/NFS m_defrag() instrumentation Message-ID: <21233.52147.912022.488615@hergotha.csail.mit.edu>
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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.) -GAWollman
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