Re: swapper: page allocation failure.

["Haar János" <djani22@netcenter.hu>]

----- Original Message ----- 
From: "Nick Piggin" <nickpiggin@yahoo.com.au>
To: "Chris Wedgwood" <cw@f00f.org>
Cc: "Haar J?nos" <djani22@netcenter.hu>; <linux-kernel@vger.kernel.org>
Sent: Sunday, May 21, 2006 2:01 PM
Subject: Re: swapper: page allocation failure.


> Chris Wedgwood wrote:
> > On Sun, May 21, 2006 at 11:31:12AM +0200, Haar J?nos wrote:
> >
> >
> >>[root@st-0001 /]# uname -a
> >>Linux st-0001 2.6.17-rc3-git1 #2 SMP Sun May 21 01:12:22 CEST 2006 i686
i686 i386 GNU/Linux
> >
> >
> > did earlier kernels work OK?
> >
> >
> >>This is a simple disk node.
> >>It serves the md0 array, and uses mem for buffering-caching.
> >
> >
> > odd, i looks like you've leaked alot of lowmem but i can't think why
> >
> > i've got major (induced) brain-fog right now so i'll have to think
> > about it tomorrow sorry
>
> The buffers are buffercache rather than the usual pagecache; due to
> nbd I guess. Buffercache cannot be satisfied by highmem.
>
> This would be a relatively uncommon setup, which explains why it
> isn't working 100%. I don't know of any reason why reclaim speed
> should be worse for buffercache, however one notable thing will be
> that zone_normal's lowmem reserve that is untouchable by pagecache
> will be eaten by buffercache...
>
> Anyway, increasing /proc/sys/vm/min_free_kbytes should help. Janos,
> perhaps you could try doubling it and see how you go?

I did it allready, and it looks like solves the problem.
Yesterday i have more than 6 random reboots, and after i set from 3800 to
16000 the min free limit, i have none at this point. :-)

 15:51:45 up  7:21,  1 user,  load average: 0.85, 0.79, 0.67

Anyway, i interested about cache/buffer mechanism, because i have some
performance problems too, and i can see, these systems wastes the half of
memory instead of speeds up the operation.

Thanks,
Janos

>
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> SUSE Labs, Novell Inc.
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