xprtrdma: Avoid using Write list for small NFS READ requests
Avoid the latency and interrupt overhead of registering a Write chunk when handling NFS READ requests of a few hundred bytes or less. This change does not interoperate with Linux NFS/RDMA servers that do not have commit 9d11b51c ('svcrdma: Fix send_reply() scatter/gather set-up'). Commit 9d11b51c was introduced in v4.3, and is included in 4.2.y, 4.1.y, and 3.18.y. Oracle bug 22925946 has been filed to request that the above fix be included in the Oracle Linux UEK4 NFS/RDMA server. Red Hat bugzillas 1327280 and 1327554 have been filed to request that RHEL NFS/RDMA server backports include the above fix. Workaround: Replace the "proto=rdma,port=20049" mount options with "proto=tcp" until commit 9d11b51c is applied to your NFS server. Signed-off-by:Chuck Lever <chuck.lever@oracle.com> Tested-by:
Steve Wise <swise@opengridcomputing.com> Reviewed-by:
Sagi Grimberg <sagi@grimberg.me> Signed-off-by:
Anna Schumaker <Anna.Schumaker@Netapp.com>
parent
302d3deb
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