From 3b1d92c56514987010bb0201b5c71aeb633fc4f8 Mon Sep 17 00:00:00 2001 From: Mel Gorman Date: Sun, 6 May 2007 14:49:30 -0700 Subject: [PATCH] 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 Acked-by: Christoph Lameter Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/page_alloc.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index f564717..542fc08 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; } -- 2.7.4