[PATCH] mm/page-writeback.c: remove outdated comment

[PATCH] mm/page-writeback.c: remove outdated comment

[Jianyu Zhan]

There is an orphaned prehistoric comment , which used to be against
get_dirty_limits(), the dawn of global_dirtyable_memory().

Back then, the implementation of get_dirty_limits() is complicated and
full of magic numbers, so this comment is necessary. But we now
use the clear and neat global_dirtyable_memory(), which renders this
comment ambiguous and useless. Remove it.

Signed-off-by: Jianyu Zhan <nasa4836@gmail.com>
---
 mm/page-writeback.c | 18 ------------------
 1 file changed, 18 deletions(-)

diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index a4317da..f2683ac 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -156,24 +156,6 @@ static unsigned long writeout_period_time = 0;
 #define VM_COMPLETIONS_PERIOD_LEN (3*HZ)
 
 /*
- * Work out the current dirty-memory clamping and background writeout
- * thresholds.
- *
- * The main aim here is to lower them aggressively if there is a lot of mapped
- * memory around.  To avoid stressing page reclaim with lots of unreclaimable
- * pages.  It is better to clamp down on writers than to start swapping, and
- * performing lots of scanning.
- *
- * We only allow 1/2 of the currently-unmapped memory to be dirtied.
- *
- * We don't permit the clamping level to fall below 5% - that is getting rather
- * excessive.
- *
- * We make sure that the background writeout level is below the adjusted
- * clamping level.
- */
-
-/*
  * In a memory zone, there is a certain amount of pages we consider
  * available for the page cache, which is essentially the number of
  * free and reclaimable pages, minus some zone reserves to protect
-- 
2.0.0

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Re: [PATCH] mm/page-writeback.c: remove outdated comment

[Johannes Weiner]

On Mon, Jun 02, 2014 at 05:47:20PM +0800, Jianyu Zhan wrote:
> There is an orphaned prehistoric comment , which used to be against
> get_dirty_limits(), the dawn of global_dirtyable_memory().
> 
> Back then, the implementation of get_dirty_limits() is complicated and
> full of magic numbers, so this comment is necessary. But we now
> use the clear and neat global_dirtyable_memory(), which renders this
> comment ambiguous and useless. Remove it.
> 
> Signed-off-by: Jianyu Zhan <nasa4836@gmail.com>

Acked-by: Johannes Weiner <hannes@cmpxchg.org>

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