Module Name: src
Committed By: simonb
Date: Sat Jul 24 13:42:05 UTC 2021
Modified Files:
src/usr.bin/systat: vmstat.c
Log Message:
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.
To generate a diff of this commit:
cvs rdiff -u -r1.88 -r1.89 src/usr.bin/systat/vmstat.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/usr.bin/systat/vmstat.c
diff -u src/usr.bin/systat/vmstat.c:1.88 src/usr.bin/systat/vmstat.c:1.89
--- src/usr.bin/systat/vmstat.c:1.88 Mon Mar 2 09:50:12 2020
+++ src/usr.bin/systat/vmstat.c Sat Jul 24 13:42:05 2021
@@ -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,
