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If we're only doing a count-only kern.buf sysctl, just return the number 

of active members in the pool cache (plus some slop) instead of looking
in all the free buffer list.  Should reduce CPU usage for "systat vm"
to << 1% especially for machines with a larger number of buffers.
This commit is contained in:
simonb 2021-07-25 06:06:40 +00:00
parent ccad6aa52f
commit 6947b62866
1 changed files with 10 additions and 4 deletions
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14
sys/kern/vfs_bio.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: vfs_bio.c,v 1.300 2021/07/24 13:28:14 simonb Exp $ */
/* $NetBSD: vfs_bio.c,v 1.301 2021/07/25 06:06:40 simonb Exp $ */
/*-
* Copyright (c) 2007, 2008, 2009, 2019, 2020 The NetBSD Foundation, Inc.
@ -123,7 +123,7 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: vfs_bio.c,v 1.300 2021/07/24 13:28:14 simonb Exp $");
__KERNEL_RCSID(0, "$NetBSD: vfs_bio.c,v 1.301 2021/07/25 06:06:40 simonb Exp $");
#ifdef _KERNEL_OPT
#include "opt_bufcache.h"
@ -1804,6 +1804,14 @@ sysctl_dobuf(SYSCTLFN_ARGS)
elem_size < 1 || elem_count < 0)
return (EINVAL);
if (oldp == NULL) {
/* count only, don't run through the buffer queues */
needed = pool_cache_nget(buf_cache) - pool_cache_nput(buf_cache);
*oldlenp = (needed + KERN_BUFSLOP) * elem_size;
return 0;
}
error = 0;
needed = 0;
sysctl_unlock();
@ -1848,8 +1856,6 @@ sysctl_dobuf(SYSCTLFN_ARGS)
sysctl_relock();
*oldlenp = needed;
if (oldp == NULL)
*oldlenp += KERN_BUFSLOP * elem_size;
return (error);
}