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author | Chuck Lever <chuck.lever@oracle.com> | 2020-05-29 21:14:40 +0300 |
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committer | Anna Schumaker <Anna.Schumaker@Netapp.com> | 2020-06-11 20:33:48 +0300 |
commit | ba838a75e73f55a780f1ee896b8e3ecb032dba0f (patch) | |
tree | 77afff1e2a6b81553cfa3d640411553a473d39d7 /net/sunrpc/auth_gss | |
parent | 94afd9c489fe6720ea3f49084125344e22610880 (diff) | |
download | linux-ba838a75e73f55a780f1ee896b8e3ecb032dba0f.tar.xz |
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>
Diffstat (limited to 'net/sunrpc/auth_gss')
0 files changed, 0 insertions, 0 deletions