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authorMel Gorman <mel@csn.ul.ie>2007-05-06 14:49:30 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-05-07 12:12:53 -0700
commit3b1d92c56514987010bb0201b5c71aeb633fc4f8 (patch)
treef31a72692c35eb27fc94590964ba389776c0439f /mm
parent8da3430d8a7f885c2bf65121181d76c9d290a86e (diff)
Do not disable interrupts when reading min_free_kbytes
The sysctl handler for min_free_kbytes calls setup_per_zone_pages_min() on read or write. This function iterates through every zone and calls spin_lock_irqsave() on the zone LRU lock. When reading min_free_kbytes, this is a total waste of time that disables interrupts on the local processor. It might even be noticable machines with large numbers of zones if a process started constantly reading min_free_kbytes. This patch only calls setup_per_zone_pages_min() only on write. Tested on an x86 laptop and it did the right thing. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Christoph Lameter <clameter@engr.sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/page_alloc.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index f564717d22f..542fc088ff5 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3199,7 +3199,8 @@ int min_free_kbytes_sysctl_handler(ctl_table *table, int write,
struct file *file, void __user *buffer, size_t *length, loff_t *ppos)
{
proc_dointvec(table, write, file, buffer, length, ppos);
- setup_per_zone_pages_min();
+ if (write)
+ setup_per_zone_pages_min();
return 0;
}