Messages in this thread | | | Date | Thu, 09 Oct 2008 09:32:03 +0200 | From | Andrea Righi <> | Subject | Re: [PATCH] documentation: clarify dirty_ratio and dirty_background_ratio description |
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KAMEZAWA Hiroyuki wrote: > On Wed, 08 Oct 2008 12:52:28 +0200 > Andrea Righi <righi.andrea@gmail.com> 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 <righi.andrea@gmail.com> > > 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 <kamezawa.hiroyu@jp.fujitsu.com>
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 >> ------------------------- >>
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