System experiences memory shortage when using nxge with jumbo frames and NFS

(Doc ID 1353254.1)

Last updated on AUGUST 01, 2016

Applies to:

Solaris Operating System - Version 10 3/05 to 10 9/10 U9 [Release 10.0]
Information in this document applies to any platform.

Symptoms

This issue typically happens for NFS clients with 1MB wsize parameter set (this is the default in most cases) - and only when using an nxge interface with jumbo frames.   

Verify the wsize setting with "nfsstat -m".   

Memory utilization in the "kmem_oversize" area is affected.  View kernel memory utilization info with the mdb "kmastat" dcmd:

  # echo ::kmastat | mdb -k

The kmem_oversize area will indicate a very large amount of memory in use.  Note that this is typically somewhat high - a few GB on large memory machines is not abnormal.    Seeing kmem_oversize extremely large, and growing when NFS writes are being done is the signature of this issue.

Changes

The issue is only seen with nxge interfaces using jumbo frames, and large data transfers from  above - typically NFS using 1MB wsize parameter is involved.  

It may be possible that an application issuing writes of at least 1MB can trigger this memory leak as well.   

Cause

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