From mboxrd@z Thu Jan 1 00:00:00 1970 Received: by mu-out-0910.google.com with SMTP id i2so3400414mue.6 for ; Wed, 08 Oct 2008 03:52:32 -0700 (PDT) Message-ID: <48EC90EC.8060306@gmail.com> Date: Wed, 08 Oct 2008 12:52:28 +0200 From: Andrea Righi Reply-To: righi.andrea@gmail.com MIME-Version: 1.0 Subject: [PATCH] documentation: clarify dirty_ratio and dirty_background_ratio description Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Randy Dunlap , Michael Kerrisk Cc: Peter Zijlstra , KAMEZAWA Hiroyuki , Andrew Morton , Michael Rubin , KOSAKI Motohiro , linux-mm@kvack.org, LKML List-ID: The current documentation of dirty_ratio and dirty_background_ratio is a bit misleading. In the documentation we say that they are "a percentage of total system memory", but the current page writeback policy, intead, is to apply the percentages to the dirtyable memory, that means free pages + reclaimable pages. Better to be more explicit to clarify this concept. Signed-off-by: Andrea Righi --- Documentation/filesystems/proc.txt | 11 ++++++----- 1 files changed, 6 insertions(+), 5 deletions(-) diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt index f566ad9..be69c8b 100644 --- a/Documentation/filesystems/proc.txt +++ b/Documentation/filesystems/proc.txt @@ -1380,15 +1380,16 @@ causes the kernel to prefer to reclaim dentries and inodes. dirty_background_ratio ---------------------- -Contains, as a percentage of total system memory, the number of pages at which -the pdflush background writeback daemon will start writing out dirty data. +Contains, as a percentage of the dirtyable system memory (free pages + +reclaimable pages), the number of pages at which the pdflush background +writeback daemon will start writing out dirty data. dirty_ratio ----------------- -Contains, as a percentage of total system memory, the number of pages at which -a process which is generating disk writes will itself start writing out dirty -data. +Contains, as a percentage of the dirtyable system memory (free pages + +reclaimable pages), the number of pages at which a process which is generating +disk writes will itself start writing out dirty data. dirty_writeback_centisecs ------------------------- -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org