The patch titled
writeback: remove the internal 5% low bound on dirty_ratio
has been added to the -mm tree. Its filename is
writeback-remove-the-internal-5%-low-bound-on-dirty_ratio.patch
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------------------------------------------------------
Subject: writeback: remove the internal 5% low bound on dirty_ratio
From: Wu Fengguang <fengguang.wu@xxxxxxxxx>
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@xxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Proposed-by: Con Kolivas <kernel@xxxxxxxxxxx>
Acked-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Reviewed-by: Rik van Riel <riel@xxxxxxxxxx>
Reviewed-by: Neil Brown <neilb@xxxxxxx>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
Cc: Michael Rubin <mrubin@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/fs-writeback.c | 2 +-
mm/page-writeback.c | 16 +++++-----------
2 files changed, 6 insertions(+), 12 deletions(-)
diff -puN fs/fs-writeback.c~writeback-remove-the-internal-5%-low-bound-on-dirty_ratio fs/fs-writeback.c
--- a/fs/fs-writeback.c~writeback-remove-the-internal-5%-low-bound-on-dirty_ratio
+++ a/fs/fs-writeback.c
@@ -593,7 +593,7 @@ static inline bool over_bground_thresh(v
global_dirty_limits(&background_thresh, &dirty_thresh);
return (global_page_state(NR_FILE_DIRTY) +
- global_page_state(NR_UNSTABLE_NFS) >= background_thresh);
+ global_page_state(NR_UNSTABLE_NFS) > background_thresh);
}
/*
diff -puN mm/page-writeback.c~writeback-remove-the-internal-5%-low-bound-on-dirty_ratio mm/page-writeback.c
--- a/mm/page-writeback.c~writeback-remove-the-internal-5%-low-bound-on-dirty_ratio
+++ a/mm/page-writeback.c
@@ -415,14 +415,8 @@ void global_dirty_limits(unsigned long *
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 a
* 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 a
* 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;
_
Patches currently in -mm which might be from fengguang.wu@xxxxxxxxx are
linux-next.patch
fs-inodec-work-around-bug.patch
vfs-introduce-fmode_neg_offset-for-allowing-negative-f_pos.patch
vfs-introduce-fmode_neg_offset-for-allowing-negative-f_pos-fix.patch
documentation-filesystems-proctxt-improve-smaps-field-documentation.patch
mm-smaps-export-mlock-information.patch
writeback-remove-nonblocking-encountered_congestion-references.patch
mm-compaction-fix-compactpagefailed-counting.patch
memory-hotplug-fix-notifiers-return-value-check.patch
memory-hotplug-unify-is_removable-and-offline-detection-code.patch
mm-add-account_page_writeback.patch
writeback-add-nr_dirtied-and-nr_written-to-proc-vmstat.patch
writeback-add-nr_dirtied-and-nr_written-to-proc-vmstat-update.patch
writeback-add-sys-devices-system-node-node-vmstat.patch
writeback-add-sys-devices-system-node-node-vmstat-update.patch
writeback-report-dirty-thresholds-in-proc-vmstat.patch
tracing-vmscan-add-trace-events-for-lru-list-shrinking.patch
writeback-account-for-time-spent-congestion_waited.patch
vmscan-synchronous-lumpy-reclaim-should-not-call-congestion_wait.patch
vmscan-narrow-the-scenarios-lumpy-reclaim-uses-synchrounous-reclaim.patch
vmscan-remove-dead-code-in-shrink_inactive_list.patch
vmscan-isolated_lru_pages-stop-neighbour-search-if-neighbour-cannot-be-isolated.patch
writeback-do-not-sleep-on-the-congestion-queue-if-there-are-no-congested-bdis.patch
writeback-do-not-sleep-on-the-congestion-queue-if-there-are-no-congested-bdis-or-if-significant-congestion-is-not-being-encountered-in-the-current-zone.patch
writeback-do-not-sleep-on-the-congestion-queue-if-there-are-no-congested-bdis-or-if-significant-congestion-is-not-being-encounted-in-the-current-zone-fix.patch
writeback-remove-the-internal-5%-low-bound-on-dirty_ratio.patch
--
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