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| author | Bron Gondwana <brong@fastmail.fm> | 2008-02-04 22:29:20 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2008-02-05 09:44:18 -0800 |
| commit | 195cf453d2c3d789cbe80e3735755f860c2fb222 (patch) | |
| tree | fad48a8167744b6c091c8ca499bc78b859af8957 /mm/page-writeback.c | |
| parent | 3dfa5721f12c3d5a441448086bee156887daa961 (diff) | |
| download | lwn-195cf453d2c3d789cbe80e3735755f860c2fb222.tar.gz lwn-195cf453d2c3d789cbe80e3735755f860c2fb222.zip | |
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 <brong@fastmail.fm>
Cc: Ethan Solomita <solo@google.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: WU Fengguang <wfg@mail.ustc.edu.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/page-writeback.c')
| -rw-r--r-- | mm/page-writeback.c | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 8137482abd6e..c689b60af000 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -69,6 +69,12 @@ 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 */ int vm_dirty_ratio = 10; @@ -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 */ } |