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authorPaul Mundt <lethal@linux-sh.org>2009-01-08 12:04:47 +0000
committerDavid Howells <dhowells@redhat.com>2009-01-08 12:04:47 +0000
commitdd8632a12e500a684478fea0951f380478d56fed (patch)
tree1a12f441f9de14fd233faa92cf13a5fbb0319f41 /kernel
parent8feae13110d60cc6287afabc2887366b0eb226c2 (diff)
NOMMU: Make mmap allocation page trimming behaviour configurable.
NOMMU mmap allocates a piece of memory for an mmap that's rounded up in size to the nearest power-of-2 number of pages. Currently it then discards the excess pages back to the page allocator, making that memory available for use by other things. This can, however, cause greater amount of fragmentation. To counter this, a sysctl is added in order to fine-tune the trimming behaviour. The default behaviour remains to trim pages aggressively, while this can either be disabled completely or set to a higher page-granular watermark in order to have finer-grained control. vm region vm_top bits taken from an earlier patch by David Howells. Signed-off-by: Paul Mundt <lethal@linux-sh.org> Signed-off-by: David Howells <dhowells@redhat.com> Tested-by: Mike Frysinger <vapier.adi@gmail.com>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/sysctl.c14
1 files changed, 14 insertions, 0 deletions
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 92f6e5bc3c2..89d74436318 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -82,6 +82,9 @@ extern int percpu_pagelist_fraction;
extern int compat_log;
extern int latencytop_enabled;
extern int sysctl_nr_open_min, sysctl_nr_open_max;
+#ifndef CONFIG_MMU
+extern int sysctl_nr_trim_pages;
+#endif
#ifdef CONFIG_RCU_TORTURE_TEST
extern int rcutorture_runnable;
#endif /* #ifdef CONFIG_RCU_TORTURE_TEST */
@@ -1102,6 +1105,17 @@ static struct ctl_table vm_table[] = {
.mode = 0644,
.proc_handler = &proc_dointvec
},
+#else
+ {
+ .ctl_name = CTL_UNNUMBERED,
+ .procname = "nr_trim_pages",
+ .data = &sysctl_nr_trim_pages,
+ .maxlen = sizeof(sysctl_nr_trim_pages),
+ .mode = 0644,
+ .proc_handler = &proc_dointvec_minmax,
+ .strategy = &sysctl_intvec,
+ .extra1 = &zero,
+ },
#endif
{
.ctl_name = VM_LAPTOP_MODE,