lkml.org 
[lkml]   [2001]   [Dec]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: 2.4.16 & OOM killer screw up (fwd)
On Wed, Dec 12, 2001 at 07:45:45AM -0200, Rik van Riel wrote:
> On Wed, 12 Dec 2001, Andrea Arcangeli wrote:
> > On Wed, Dec 12, 2001 at 12:44:17AM -0800, Andrew Morton wrote:
> > > Oh. Maybe the core design (whatever it is :)) is not finished,
> > > because it retains the bone-headed, dumb-to-the-point-of-astonishing
> > > misfeature which Linux VM has always had:
> > >
> > > If someone is linearly writing (or reading) a gigabyte file on a 64
> > > megabyte box they *don't* want the VM to evict every last little scrap
> > > of cache on behalf of data which they *obviously* do not want
> > > cached.
> >
> > The current design tries to detect this, at least much much better than
> > 2.2. This is why I disagree with Rik's patch of yesterday. detecting
> > cache pollution is good also on the lowmem boxes (not only for DB).
>
> Oh, absolutely. The problem just is that the current design
> has even worse problems where it doesn't put any pressure on
> pages which were touched twice an hour ago.

it does. See the refill_inactive pass.

> This leads to the situation that applications get OOM-killed
> to preserve buffer cache memory which hasn't been touched
> since bootup time.

It doesn't happen here.

At the very least the fix is the two liner from Andrew that forces a
nr_pages refile from active list, that will guarantee that whatever
happens we always roll the active list too, but the oom killing you are
experiencing is a problem of mainline, it definitely doesn't happen here
and the refill_inactive(0) cannot be the culprit because the active list
grows always to a relevant size and if during oom a few pages stays
untouched into the active list that's fine, those two pages couldn't
save us anyways so they'd better stay there so we don't trash.

>
> There are ways to both have good behaviour on bulk IO and
> flush out old data which was in active use but no longer is.
> I believe these are called page aging and drop-behind.
> I've been thinking about achieving the wanted behaviour
> without these two, but haven't been able to come up with
> any algorithm which doesn't have some very bad side effects.
>
> If you know a way of doing bulk IO properly and flushing out
> an old working set correctly, please let us know.
>
> regards,
>
> Rik
> --
> Shortwave goes a long way: irc.starchat.net #swl
>
> http://www.surriel.com/ http://distro.conectiva.com/


Andrea
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 13:14    [W:0.069 / U:0.272 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site