Aren
/
NetBSD
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Instead of getting an estimate of the number of kernel buffers, 

allocating memory for them, requesting all the metadata contents of
these buffers (and repeating in the unlikely case of the number of
buffers increasing too much since the estimate) and then straight away
throwing all the contents out just to count how many buffers there were,
just get the initial estimate from the kernel and subtract the slop.

Reduces system CPU usage of "systat vm" by approx 80% for any system
with a reasonable number of buffers.
This commit is contained in:
simonb 2021-07-24 13:42:05 +00:00
parent 44f4ec8e31
commit 12d3157b50
1 changed files with 3 additions and 22 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

25
usr.bin/systat/vmstat.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: vmstat.c,v 1.88 2020/03/02 09:50:12 mrg Exp $ */
/* $NetBSD: vmstat.c,v 1.89 2021/07/24 13:42:05 simonb Exp $ */
/*-
* Copyright (c) 1983, 1989, 1992, 1993
@ -34,7 +34,7 @@
#if 0
static char sccsid[] = "@(#)vmstat.c 8.2 (Berkeley) 1/12/94";
#endif
__RCSID("$NetBSD: vmstat.c,v 1.88 2020/03/02 09:50:12 mrg Exp $");
__RCSID("$NetBSD: vmstat.c,v 1.89 2021/07/24 13:42:05 simonb Exp $");
#endif /* not lint */
/*
@ -481,10 +481,8 @@ showvmstat(void)
static int relabel = 0;
static int last_disks = 0;
static u_long bufmem;
struct buf_sysctl *buffers;
int mib[6];
size_t size;
int extraslop = 0;
if (relabel) {
labelvmstat();
@ -528,14 +526,12 @@ showvmstat(void)
/* Get number of metadata buffers */
size = 0;
buffers = NULL;
mib[0] = CTL_KERN;
mib[1] = KERN_BUF;
mib[2] = KERN_BUF_ALL;
mib[3] = KERN_BUF_ALL;
mib[4] = (int)sizeof(struct buf_sysctl);
mib[5] = INT_MAX; /* we want them all */
again:
if (sysctl(mib, 6, NULL, &size, NULL, 0) < 0) {
error("can't get buffers size: %s\n", strerror(errno));
return;
@ -544,23 +540,8 @@ again:
error("buffers size is zero: %s\n", strerror(errno));
return;
}
size += extraslop * sizeof(struct buf_sysctl);
buffers = malloc(size);
if (buffers == NULL) {
error("can't allocate buffers: %s\n", strerror(errno));
return;
}
if (sysctl(mib, 6, buffers, &size, NULL, 0) < 0) {
free(buffers);
if (extraslop < 1000) {
extraslop += 100;
goto again;
}
error("can't get buffers: %s\n", strerror(errno));
return;
}
free(buffers); /* XXX there must be a better way! */
nbuf = size / sizeof(struct buf_sysctl);
nbuf -= KERN_BUFSLOP;
putint((int) (bufmem / 1024), MEMROW + 3, MEMCOL + 5, 12);
putint((int) ((bufmem * 100) + 0.5) / s.uvmexp.pagesize / s.uvmexp.npages,