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| author | Chuck Lever <chuck.lever@oracle.com> | 2020-05-29 21:14:40 +0300 |
|---|---|---|
| committer | Anna Schumaker <Anna.Schumaker@Netapp.com> | 2020-06-11 20:33:48 +0300 |
| commit | ba838a75e73f55a780f1ee896b8e3ecb032dba0f (patch) | |
| tree | 77afff1e2a6b81553cfa3d640411553a473d39d7 | |
| 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>
| -rw-r--r-- | fs/nfs/direct.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c index bb63e2b93ff7..1b79dd5cf661 100644 --- a/fs/nfs/direct.c +++ b/fs/nfs/direct.c @@ -731,6 +731,8 @@ static void nfs_direct_write_completion(struct nfs_pgio_header *hdr) nfs_list_remove_request(req); if (request_commit) { kref_get(&req->wb_kref); + memcpy(&req->wb_verf, &hdr->verf.verifier, + sizeof(req->wb_verf)); nfs_mark_request_commit(req, hdr->lseg, &cinfo, hdr->ds_commit_idx); } |