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authorChuck Lever <chuck.lever@oracle.com>2021-09-30 19:10:03 -0400
committerChuck Lever <chuck.lever@oracle.com>2021-12-13 13:42:59 -0500
commit7578b2f628db27281d3165af0aa862311883a858 (patch)
tree5c034380b0eb3c31f47eeb37a669ec52ac00c44d /fs/nfsd/nfscache.c
parent23a1a573c61ccb5e7829c1f5472d3e025293a031 (diff)
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>
Diffstat (limited to 'fs/nfsd/nfscache.c')
-rw-r--r--fs/nfsd/nfscache.c2
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 *