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| author |   Chuck Lever <chuck.lever@oracle.com> | 2021-09-30 19:10:03 -0400 |
|---|---|---|
| committer | Chuck Lever <chuck.lever@oracle.com> | 2021-12-13 13:42:59 -0500 |
| commit | 7578b2f628db27281d3165af0aa862311883a858 (patch) | |
| tree | 5c034380b0eb3c31f47eeb37a669ec52ac00c44d | |
| parent | NFS: switch the callback service back to non-pooled. (diff) | |
| download | linux-dev-7578b2f628db27281d3165af0aa862311883a858.tar.xz linux-dev-7578b2f628db27281d3165af0aa862311883a858.zip | |
NFSD: Remove be32_to_cpu() from DRC hash function
Commit 7142b98d9fd7 ("nfsd: Clean up drc cache in preparation for
global spinlock elimination"), billed as a clean-up, added
be32_to_cpu() to the DRC hash function without explanation. That
commit removed two comments that state that byte-swapping in the
hash function is unnecessary without explaining whether there was
a need for that change.
On some Intel CPUs, the swab32 instruction is known to cause a CPU
pipeline stall. be32_to_cpu() does not add extra randomness, since
the hash multiplication is done /before/ shifting to the high-order
bits of the result.
As a micro-optimization, remove the unnecessary transform from the
DRC hash function.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
| -rw-r--r-- | fs/nfsd/nfscache.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/nfsd/nfscache.c b/fs/nfsd/nfscache.c index 6e0b6f3148dc..a4a69ab6ab28 100644 --- a/fs/nfsd/nfscache.c +++ b/fs/nfsd/nfscache.c @@ -87,7 +87,7 @@ nfsd_hashsize(unsigned int limit) static u32 nfsd_cache_hash(__be32 xid, struct nfsd_net *nn) { - return hash_32(be32_to_cpu(xid), nn->maskbits); + return hash_32((__force u32)xid, nn->maskbits); } static struct svc_cacherep * |