From mboxrd@z Thu Jan 1 00:00:00 1970 Received: by ey-out-1920.google.com with SMTP id 21so1755247eyc.44 for ; Thu, 09 Oct 2008 00:31:51 -0700 (PDT) Message-ID: <48EDB373.2050704@gmail.com> Date: Thu, 09 Oct 2008 09:32:03 +0200 From: Andrea Righi Reply-To: righi.andrea@gmail.com MIME-Version: 1.0 Subject: Re: [PATCH] documentation: clarify dirty_ratio and dirty_background_ratio description References: <48EC90EC.8060306@gmail.com> <20081009105157.dd47d109.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20081009105157.dd47d109.kamezawa.hiroyu@jp.fujitsu.com> Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: KAMEZAWA Hiroyuki Cc: Randy Dunlap , Michael Kerrisk , Peter Zijlstra , Andrew Morton , Michael Rubin , KOSAKI Motohiro , linux-mm@kvack.org, LKML List-ID: KAMEZAWA Hiroyuki wrote: > On Wed, 08 Oct 2008 12:52:28 +0200 > Andrea Righi wrote: > >> 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. >> > Right. > >> Better to be more explicit to clarify this concept. >> >> Signed-off-by: Andrea Righi > > But I wonder "reclaimable memory" seems to be a difficult word for users.... > > "free pages + mapped pages + file cache, not including locked page and HugePage" > ? > Anyway, > Acked-by: KAMEZAWA Hiroyuki Sounds better. I'll add these details and post a new patch. Thanks, -Andrea > >> --- >> 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