Messages in this thread Patch in this message | | | Date | Mon, 26 Mar 2007 11:03:29 +0100 | Subject | [PATCH] Do not disable interrupts when reading min_free_kbytes | From | (Mel Gorman) |
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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> ---
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 majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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