Bug 114654

Summary:	[vm] [patch] make vm_page_max_wired tunnable at run time
Product:	Base System	Reporter:	Eugene Grosbein <ports>
Component:	kern	Assignee:	Alan Cox <alc>
Status:	Closed FIXED
Severity:	Affects Only Me
Priority:	Normal
Version:	6.2-STABLE
Hardware:	Any
OS:	Any

Description Eugene Grosbein 2007-07-17 12:50:02 UTC

	The kernel limits number of pages mlock()'ed by a process
	to one third of vm.stats.vm.v_free_count to prevent damage
	from broken processes. However, sometimes there is a need to allow
	a process to mlock() more than half of free pages pool,
	one example is /usr/ports/sysutils/memtest.
	Let's make vm_page_max_wired tunnable at run time.

Fix: Running kernel with the following patch, I may increase
	sysctl vm.max_wired value upto, say, 1.5Gb
	for the system having 2Gb RAM and still run memtest from X.org's
	xterm session (top shows "1802M Free" here).



Eugene Grosbein--mzUjhPbKqyaLzGWhnh4FijxbkHiPQLS0MwuOUUoJ3i6Z01lK
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--- sys/vm/vm_pageout.c.orig	Tue Jul 17 19:18:56 2007
+++ sys/vm/vm_pageout.c	Tue Jul 17 19:33:52 2007
@@ -203,6 +203,8 @@
 int vm_pageout_page_count = VM_PAGEOUT_PAGE_COUNT;
 
 int vm_page_max_wired;		/* XXX max # of wired pages system-wide */
+SYSCTL_INT(_vm, OID_AUTO, max_wired,
+	CTLFLAG_RW, &vm_page_max_wired, 0, "System-wide limit to wired page count");
 
 #if !defined(NO_SWAPPING)
 static void vm_pageout_map_deactivate_pages(vm_map_t, long);
How-To-Repeat: 	I've installed second 1Gb memory module to my system and
	want to quick-check (most part of) it. I've raised kern.maxdsize
	but the kernel still does not allow memtest to mlock() so many pages.

	Yes, I know the best method is to boot the system from floppy
	of CD with special memory tester. But I'd glad to see this
	way allowed too.

Comment 1 K. Macy freebsd_committer

2007-11-16 08:02:20 UTC

Responsible Changed
From-To: freebsd-bugs->alc


This seems reasonable to me. 
alc - please let me know what you think, and close if you think it is 
simply a bad idea.

Comment 2 Alan Cox freebsd_committer

2007-11-23 00:31:21 UTC

State Changed
From-To: open->patched

Patch applied to HEAD.

Comment 3 dfilter service freebsd_committer

2007-11-23 04:39:00 UTC

alc         2007-11-23 00:30:19 UTC

  FreeBSD src repository

  Modified files:
    sys/vm               vm_pageout.c 
  Log:
  Add a read/write sysctl for reconfiguring the maximum number of physical
  pages that can be wired.
  
  Submitted by:   Eugene Grosbein
  PR:             114654
  MFC after:      6 weeks
  
  Revision  Changes    Path
  1.293     +2 -0      src/sys/vm/vm_pageout.c
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Comment 4 dfilter service freebsd_committer

2008-05-25 08:00:17 UTC

alc         2008-05-25 07:00:07 UTC

  FreeBSD src repository

  Modified files:        (Branch: RELENG_7)
    sys/vm               vm_pageout.c 
  Log:
  MFC revision 1.293
    Add a read/write sysctl for reconfiguring the maximum number of physical
    pages that can be wired.
  
  PR: 114654
  
  Revision   Changes    Path
  1.292.2.1  +2 -0      src/sys/vm/vm_pageout.c
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Comment 5 dfilter service freebsd_committer

2008-05-25 08:38:16 UTC

alc         2008-05-25 07:38:09 UTC

  FreeBSD src repository

  Modified files:        (Branch: RELENG_6)
    sys/vm               vm_pageout.c 
  Log:
  MFC revision 1.293
    Add a read/write sysctl for reconfiguring the maximum number of physical
    pages that can be wired.
  
  PR: 114654
  
  Revision   Changes    Path
  1.268.2.5  +2 -0      src/sys/vm/vm_pageout.c
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Comment 6 Alan Cox freebsd_committer

2008-05-25 08:38:45 UTC

State Changed
From-To: patched->closed

Patch applied to RELENG_7 and RELENG_6.