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kern_subr.c:

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Added a new type to uiomove - "UIO_NOCOPY" which causes it to update
pointers and counts, but doesn't do any data copying. This is needed
for upcoming changes to the way that the vnode pager does its page
outs.
Added a new hash init function call "phashinit" that allocates and
initializes a prime number sized hash table.

vfs_cache.c:
Changed hashing algorithm to use the remainder of dividing by a prime
number to improve the distribution characteristcs. Uses new phashinit
function in kern_subr.c.
This commit is contained in:
David Greenman 1995-04-04 02:01:13 +00:00
parent 2e837708b1
commit 22e53424b2
2 changed files with 41 additions and 6 deletions
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37
sys/kern/kern_subr.c
View File

@ -36,7 +36,7 @@
* SUCH DAMAGE.
*
* @(#)kern_subr.c 8.3 (Berkeley) 1/21/94
* $Id: kern_subr.c,v 1.3 1994/08/02 07:42:14 davidg Exp $
* $Id: kern_subr.c,v 1.4 1995/02/12 09:11:47 davidg Exp $
*/
#include <sys/param.h>
@ -90,6 +90,8 @@ uiomove(cp, n, uio)
else
bcopy(iov->iov_base, (caddr_t)cp, cnt);
break;
case UIO_NOCOPY:
break;
}
iov->iov_base += cnt;
iov->iov_len -= cnt;
@ -213,3 +215,36 @@ hashinit(elements, type, hashmask)
*hashmask = hashsize - 1;
return (hashtbl);
}
#define NPRIMES 24
static int primes[] = { 61, 127, 251, 509, 761, 1021, 1531, 2039, 2557,
3067, 3583, 4093, 4603, 5119, 5623, 6143, 6653,
7159, 7673, 8191, 12281, 16381, 24571, 32749 };
/*
* General routine to allocate a prime number sized hash table.
*/
void *
phashinit(elements, type, nentries)
int elements, type;
u_long *nentries;
{
long hashsize;
LIST_HEAD(generic, generic) *hashtbl;
int i;
if (elements <= 0)
panic("hashinit: bad cnt");
for (i = 1, hashsize = primes[1]; hashsize <= elements;) {
i++;
if (i == NPRIMES)
break;
hashsize = primes[i];
}
hashsize = primes[i - 1];
hashtbl = malloc((u_long)hashsize * sizeof(*hashtbl), type, M_WAITOK);
for (i = 0; i < hashsize; i++)
LIST_INIT(&hashtbl[i]);
*nentries = hashsize;
return (hashtbl);
}

10
sys/kern/vfs_cache.c
View File

@ -33,7 +33,7 @@
* SUCH DAMAGE.
*
* @(#)vfs_cache.c 8.3 (Berkeley) 8/22/94
* $Id: vfs_cache.c,v 1.11 1995/03/12 02:01:20 phk Exp $
* $Id: vfs_cache.c,v 1.12 1995/03/19 09:33:51 davidg Exp $
*/
#include <sys/param.h>
@ -72,7 +72,7 @@
*/
LIST_HEAD(nchashhead, namecache) *nchashtbl; /* Hash Table */
TAILQ_HEAD(, namecache) nclruhead; /* LRU chain */
u_long nchash; /* size of hash table - 1 */
u_long nchash; /* size of hash table */
struct nchstats nchstats; /* cache effectiveness statistics */
struct vnode nchENOENT; /* our own "novnode" */
int doingcache = 1; /* 1 => enable the cache */
@ -134,7 +134,7 @@ cache_lookup(dvp, vpp, cnp)
return (0);
}
ncpp = &nchashtbl[(dvp->v_id + cnp->cn_hash) & nchash];
ncpp = &nchashtbl[(dvp->v_id + cnp->cn_hash) % nchash];
for (ncp = ncpp->lh_first; ncp != 0; ncp = nnp) {
nnp = ncp->nc_hash.le_next;
/* If one of the vp's went stale, don't bother anymore. */
@ -235,7 +235,7 @@ cache_enter(dvp, vp, cnp)
ncp->nc_nlen = cnp->cn_namelen;
bcopy(cnp->cn_nameptr, ncp->nc_name, (unsigned)ncp->nc_nlen);
TAILQ_INSERT_TAIL(&nclruhead, ncp, nc_lru);
ncpp = &nchashtbl[(dvp->v_id + cnp->cn_hash) & nchash];
ncpp = &nchashtbl[(dvp->v_id + cnp->cn_hash) % nchash];
LIST_INSERT_HEAD(ncpp, ncp, nc_hash);
}
@ -248,7 +248,7 @@ nchinit()
{
TAILQ_INIT(&nclruhead);
nchashtbl = hashinit(desiredvnodes, M_CACHE, &nchash);
nchashtbl = phashinit(desiredvnodes, M_CACHE, &nchash);
nchENOENT.v_id = 1;
}