From 195cf453d2c3d789cbe80e3735755f860c2fb222 Mon Sep 17 00:00:00 2001 From: Bron Gondwana Date: Mon, 4 Feb 2008 22:29:20 -0800 Subject: mm/page-writeback: highmem_is_dirtyable option Add vm.highmem_is_dirtyable toggle A 32 bit machine with HIGHMEM64 enabled running DCC has an MMAPed file of approximately 2Gb size which contains a hash format that is written randomly by the dbclean process. On 2.6.16 this process took a few minutes. With lowmem only accounting of dirty ratios, this takes about 12 hours of 100% disk IO, all random writes. Include a toggle in /proc/sys/vm/highmem_is_dirtyable which can be set to 1 to add the highmem back to the total available memory count. [akpm@linux-foundation.org: Fix the CONFIG_DETECT_SOFTLOCKUP=y build] Signed-off-by: Bron Gondwana Cc: Ethan Solomita Cc: Peter Zijlstra Cc: WU Fengguang Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/page-writeback.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) (limited to 'mm/page-writeback.c') diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 8137482abd6..c689b60af00 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -68,6 +68,12 @@ static inline long sync_writeback_pages(void) */ int dirty_background_ratio = 5; +/* + * free highmem will not be subtracted from the total free memory + * for calculating free ratios if vm_highmem_is_dirtyable is true + */ +int vm_highmem_is_dirtyable; + /* * The generator of dirty data starts writeback at this percentage */ @@ -287,7 +293,10 @@ static unsigned long determine_dirtyable_memory(void) x = global_page_state(NR_FREE_PAGES) + global_page_state(NR_INACTIVE) + global_page_state(NR_ACTIVE); - x -= highmem_dirtyable_memory(x); + + if (!vm_highmem_is_dirtyable) + x -= highmem_dirtyable_memory(x); + return x + 1; /* Ensure that we never return 0 */ } -- cgit v1.2.3