lkml.org 
[lkml]   [2011]   [May]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[PATCH 3/3] swap-token: add a comment for priority aging
Add to a few comment of design decision of swap token aging.

Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
---
mm/thrash.c | 11 +++++++++++
1 files changed, 11 insertions(+), 0 deletions(-)
diff --git a/mm/thrash.c b/mm/thrash.c
index 0504e8a..8832edb 100644
--- a/mm/thrash.c
+++ b/mm/thrash.c
@@ -50,6 +50,17 @@ void grab_swap_token(struct mm_struct *mm)
if (!swap_token_mm)
goto replace_token;

+ /*
+ * Usually, we don't need priority aging because long interval faults
+ * makes priority decrease quickly. But there is one exception. If the
+ * token owner task is sleeping, it never make long interval faults.
+ * Thus, we need a priority aging mechanism instead. The requirements
+ * of priority aging are
+ * 1) An aging interval is reasonable enough long. Too short aging
+ * interval makes quick swap token lost and decrease performance.
+ * 2) The swap token owner task have to get priority aging even if
+ * it's under sleep.
+ */
if ((global_faults - last_aging) > TOKEN_AGING_INTERVAL) {
swap_token_mm->token_priority /= 2;
last_aging = global_faults;
--
1.7.3.1




\
 
 \ /
  Last update: 2011-05-25 05:15    [from the cache]
©2003-2011 Jasper Spaans