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authorChuck Lever <chuck.lever@oracle.com>2020-05-29 14:14:40 -0400
committerAnna Schumaker <Anna.Schumaker@Netapp.com>2020-06-11 13:33:48 -0400
commitba838a75e73f55a780f1ee896b8e3ecb032dba0f (patch)
tree77afff1e2a6b81553cfa3d640411553a473d39d7 /include
parentSUNRPC: rpc_xprt lifetime events should record xprt->state (diff)
downloadwireguard-linux-ba838a75e73f55a780f1ee896b8e3ecb032dba0f.tar.xz
wireguard-linux-ba838a75e73f55a780f1ee896b8e3ecb032dba0f.zip
NFS: Fix direct WRITE throughput regression
I measured a 50% throughput regression for large direct writes. The observed on-the-wire behavior is that the client sends every NFS WRITE twice: once as an UNSTABLE WRITE plus a COMMIT, and once as a FILE_SYNC WRITE. This is because the nfs_write_match_verf() check in nfs_direct_commit_complete() fails for every WRITE. Buffered writes use nfs_write_completion(), which sets req->wb_verf correctly. Direct writes use nfs_direct_write_completion(), which does not set req->wb_verf at all. This leaves req->wb_verf set to all zeroes for every direct WRITE, and thus nfs_direct_commit_completion() always sets NFS_ODIRECT_RESCHED_WRITES. This fix appears to restore nearly all of the lost performance. Fixes: 1f28476dcb98 ("NFS: Fix O_DIRECT commit verifier handling") Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
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