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authorWu Fengguang <fengguang.wu@intel.com>2010-10-26 14:21:45 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2010-10-26 16:52:08 -0700
commit4cbec4c8b9fda9ec784086fe7f74cd32a8adda95 (patch)
tree669c3df27982345b52d0bfca8026e3f275e64a03 /mm
parent0e093d99763eb4cea09f8ca4f1d01f34e121d10b (diff)
downloadvexpress-lsk-4cbec4c8b9fda9ec784086fe7f74cd32a8adda95.tar.gz
writeback: remove the internal 5% low bound on dirty_ratio
The dirty_ratio was silently limited in global_dirty_limits() to >= 5%. This is not a user expected behavior. And it's inconsistent with calc_period_shift(), which uses the plain vm_dirty_ratio value. Let's remove the internal bound. At the same time, fix balance_dirty_pages() to work with the dirty_thresh=0 case. This allows applications to proceed when dirty+writeback pages are all cleaned. And ">" fits with the name "exceeded" better than ">=" does. Neil thinks it is an aesthetic improvement as well as a functional one :) Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> Cc: Jan Kara <jack@suse.cz> Proposed-by: Con Kolivas <kernel@kolivas.org> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Reviewed-by: Rik van Riel <riel@redhat.com> Reviewed-by: Neil Brown <neilb@suse.de> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Michael Rubin <mrubin@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/page-writeback.c16
1 files changed, 5 insertions, 11 deletions
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 4dd91f7fd39..b840afa8976 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -415,14 +415,8 @@ void global_dirty_limits(unsigned long *pbackground, unsigned long *pdirty)
if (vm_dirty_bytes)
dirty = DIV_ROUND_UP(vm_dirty_bytes, PAGE_SIZE);
- else {
- int dirty_ratio;
-
- dirty_ratio = vm_dirty_ratio;
- if (dirty_ratio < 5)
- dirty_ratio = 5;
- dirty = (dirty_ratio * available_memory) / 100;
- }
+ else
+ dirty = (vm_dirty_ratio * available_memory) / 100;
if (dirty_background_bytes)
background = DIV_ROUND_UP(dirty_background_bytes, PAGE_SIZE);
@@ -510,7 +504,7 @@ static void balance_dirty_pages(struct address_space *mapping,
* catch-up. This avoids (excessively) small writeouts
* when the bdi limits are ramping up.
*/
- if (nr_reclaimable + nr_writeback <
+ if (nr_reclaimable + nr_writeback <=
(background_thresh + dirty_thresh) / 2)
break;
@@ -542,8 +536,8 @@ static void balance_dirty_pages(struct address_space *mapping,
* the last resort safeguard.
*/
dirty_exceeded =
- (bdi_nr_reclaimable + bdi_nr_writeback >= bdi_thresh)
- || (nr_reclaimable + nr_writeback >= dirty_thresh);
+ (bdi_nr_reclaimable + bdi_nr_writeback > bdi_thresh)
+ || (nr_reclaimable + nr_writeback > dirty_thresh);
if (!dirty_exceeded)
break;