Author: mjg
Date: Thu Dec 29 08:41:25 2016
New Revision: 310767
URL: https://svnweb.freebsd.org/changeset/base/310767
Log:
cache: depessimize hashing macros/inlines
All hash sizes are power-of-2, but the compiler does not know that for sure
and 'foo % size' forces doing a division.
Store the size - 1 and use 'foo & hash' instead which allows mere shift.
Modified:
head/sys/kern/vfs_cache.c
Modified: head/sys/kern/vfs_cache.c
==============================================================================
--- head/sys/kern/vfs_cache.c Thu Dec 29 08:34:50 2016 (r310766)
+++ head/sys/kern/vfs_cache.c Thu Dec 29 08:41:25 2016 (r310767)
@@ -242,26 +242,29 @@ static struct neglist ncneg_hot;
static int shrink_list_turn;
-static u_int numneglists;
+#define numneglists (ncneghash + 1)
+static u_int ncneghash;
static inline struct neglist *
NCP2NEGLIST(struct namecache *ncp)
{
- return (&neglists[(((uintptr_t)(ncp) >> 8) % numneglists)]);
+ return (&neglists[(((uintptr_t)(ncp) >> 8) & ncneghash)]);
}
-static u_int numbucketlocks;
+#define numbucketlocks (ncbuckethash + 1)
+static u_int ncbuckethash;
static struct rwlock_padalign *bucketlocks;
#define HASH2BUCKETLOCK(hash) \
- ((struct rwlock *)(&bucketlocks[((hash) % numbucketlocks)]))
+ ((struct rwlock *)(&bucketlocks[((hash) & ncbuckethash)]))
-static u_int numvnodelocks;
+#define numvnodelocks (ncvnodehash + 1)
+static u_int ncvnodehash;
static struct mtx *vnodelocks;
static inline struct mtx *
VP2VNODELOCK(struct vnode *vp)
{
- return (&vnodelocks[(((uintptr_t)(vp) >> 8) % numvnodelocks)]);
+ return (&vnodelocks[(((uintptr_t)(vp) >> 8) & ncvnodehash)]);
}
/*
@@ -1369,9 +1372,10 @@ cache_lock_vnodes_cel_3(struct celocksta
cache_assert_vlp_locked(cel->vlp[0]);
cache_assert_vlp_locked(cel->vlp[1]);
MPASS(cel->vlp[2] == NULL);
- MPASS(vp != NULL);
+ MPASS(vp != NULL);
vlp = VP2VNODELOCK(vp);
+
ret = true;
if (vlp >= cel->vlp[1]) {
mtx_lock(vlp);
@@ -1774,21 +1778,21 @@ nchinit(void *dummy __unused)
NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT);
nchashtbl = hashinit(desiredvnodes * 2, M_VFSCACHE, &nchash);
- numbucketlocks = cache_roundup_2(mp_ncpus * 64);
- if (numbucketlocks > nchash + 1)
- numbucketlocks = nchash + 1;
+ ncbuckethash = cache_roundup_2(mp_ncpus * 64) - 1;
+ if (ncbuckethash > nchash)
+ ncbuckethash = nchash;
bucketlocks = malloc(sizeof(*bucketlocks) * numbucketlocks, M_VFSCACHE,
M_WAITOK | M_ZERO);
for (i = 0; i < numbucketlocks; i++)
rw_init_flags(&bucketlocks[i], "ncbuc", RW_DUPOK | RW_RECURSE);
- numvnodelocks = cache_roundup_2(mp_ncpus * 64);
+ ncvnodehash = cache_roundup_2(mp_ncpus * 64) - 1;
vnodelocks = malloc(sizeof(*vnodelocks) * numvnodelocks, M_VFSCACHE,
M_WAITOK | M_ZERO);
for (i = 0; i < numvnodelocks; i++)
mtx_init(&vnodelocks[i], "ncvn", NULL, MTX_DUPOK | MTX_RECURSE);
ncpurgeminvnodes = numbucketlocks;
- numneglists = 4;
+ ncneghash = 3;
neglists = malloc(sizeof(*neglists) * numneglists, M_VFSCACHE,
M_WAITOK | M_ZERO);
for (i = 0; i < numneglists; i++) {
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