[PATCH 4/5] mm: Remove low limit from sync_writeback_pages()

[Jan Kara]

sync_writeback_pages() limited minimal amount of pages to write
in balance_dirty_pages() to 3/2*ratelimit_pages (6 MB) to submit
reasonably sized IO. Since we do not submit any IO anymore, be more
fair and let the task wait only for 3/2*(the amount dirtied).

CC: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
CC: Christoph Hellwig <hch@xxxxxxxxxxxxx>
CC: Dave Chinner <david@xxxxxxxxxxxxx>
CC: Wu Fengguang <fengguang.wu@xxxxxxxxx>
CC: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Signed-off-by: Jan Kara <jack@xxxxxxx>
---
 mm/page-writeback.c |    9 ++-------
 1 files changed, 2 insertions(+), 7 deletions(-)

diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 697dd8e..ff07280 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -43,16 +43,11 @@
 static long ratelimit_pages = 32;
 
 /*
- * When balance_dirty_pages decides that the caller needs to perform some
- * non-background writeback, this is how many pages it will attempt to write.
- * It should be somewhat larger than dirtied pages to ensure that reasonably
- * large amounts of I/O are submitted.
+ * When balance_dirty_pages decides that the caller needs to wait for some
+ * writeback to happen, this is how many pages it will attempt to write.
  */
 static inline long sync_writeback_pages(unsigned long dirtied)
 {
-	if (dirtied < ratelimit_pages)
-		dirtied = ratelimit_pages;
-
 	return dirtied + dirtied / 2;
 }
 
-- 
1.7.1


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