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 <[EMAIL PROTECTED]>
---
page_alloc.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff -rup -X /usr/src/patchset-0.6/bin//dontdiff
linux-2.6.21-rc4-mm1-norsdl/mm/page_alloc.c
linux-2.6.21-rc4-mm1-nodisable_on_read_minfree/mm/page_alloc.c
--- linux-2.6.21-rc4-mm1-norsdl/mm/page_alloc.c 2007-03-26 09:56:32.000000000
+0100
+++ linux-2.6.21-rc4-mm1-nodisable_on_read_minfree/mm/page_alloc.c
2007-03-26 10:39:46.000000000 +0100
@@ -3956,7 +3956,8 @@ int min_free_kbytes_sysctl_handler(ctl_t
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;
}
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [EMAIL PROTECTED]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
