Revision 195cb14fa3955986d950210d3779c7f52c8a2bbb authored by Alan Cox on 10 November 2011, 16:50:36 UTC, committed by Alan Cox on 10 November 2011, 16:50:36 UTC
Speed up vm_page_cache() and vm_page_remove() by checking for a few common cases that can be handled in constant time. Approved by: re (kib)
1 parent c577a7c
kinfo_getvmmap.c
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/user.h>
#include <sys/sysctl.h>
#include <stdlib.h>
#include <string.h>
#include "libutil.h"
struct kinfo_vmentry *
kinfo_getvmmap(pid_t pid, int *cntp)
{
int mib[4];
int error;
int cnt;
size_t len;
char *buf, *bp, *eb;
struct kinfo_vmentry *kiv, *kp, *kv;
*cntp = 0;
len = 0;
mib[0] = CTL_KERN;
mib[1] = KERN_PROC;
mib[2] = KERN_PROC_VMMAP;
mib[3] = pid;
error = sysctl(mib, 4, NULL, &len, NULL, 0);
if (error)
return (NULL);
len = len * 4 / 3;
buf = malloc(len);
if (buf == NULL)
return (NULL);
error = sysctl(mib, 4, buf, &len, NULL, 0);
if (error) {
free(buf);
return (NULL);
}
/* Pass 1: count items */
cnt = 0;
bp = buf;
eb = buf + len;
while (bp < eb) {
kv = (struct kinfo_vmentry *)(uintptr_t)bp;
bp += kv->kve_structsize;
cnt++;
}
kiv = calloc(cnt, sizeof(*kiv));
if (kiv == NULL) {
free(buf);
return (NULL);
}
bp = buf;
eb = buf + len;
kp = kiv;
/* Pass 2: unpack */
while (bp < eb) {
kv = (struct kinfo_vmentry *)(uintptr_t)bp;
/* Copy/expand into pre-zeroed buffer */
memcpy(kp, kv, kv->kve_structsize);
/* Advance to next packed record */
bp += kv->kve_structsize;
/* Set field size to fixed length, advance */
kp->kve_structsize = sizeof(*kp);
kp++;
}
free(buf);
*cntp = cnt;
return (kiv); /* Caller must free() return value */
}
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