Re: swapper: page allocation failure.

[Haar János]

----- Original Message ----- 
From: "Con Kolivas" <kernel@xxxxxxxxxxx>
To: <linux-kernel@xxxxxxxxxxxxxxx>
Cc: "Haar János" <djani22@xxxxxxxxxxxx>; "Nick Piggin"
<nickpiggin@xxxxxxxxxxxx>; <cw@xxxxxxxx>
Sent: Monday, May 22, 2006 1:17 PM
Subject: Re: swapper: page allocation failure.


> On Monday 22 May 2006 17:41, Haar János wrote:
> > ----- Original Message -----
> > From: "Nick Piggin" <nickpiggin@xxxxxxxxxxxx>
> > > Yeah, as I said, block device's pagecache (aka buffercache) can't
> > > use highmem. If nbd can export regular files as block devices, or
> > > you use loop devices from regular files, that might help (or slow
> > > things down :P).
> >
> > Hmm.
> > That sounds bad.
> > I think, if highmem is unreachable some times that makes lowmem more
> > valuable!
> > The kernel needs to keep (reserve) it free as much as possible.
> > The buffer-cache is an unimportant thing next to keeping lowmem free,
but
> > it is blocks the performance and wastes the systems resources!
> >
> > It is possible any workaround?
>
> Try with one of the alternative vmsplit options that gives you more
lowmem?
> That might break certain applications though.

             total       used       free     shared    buffers     cached
Mem:       4049724    4021196      28528          0      16384    3217288
Low:       4049724    4021196      28528
High:            0          0          0
-/+ buffers/cache:     787524    3262200
Swap:            0          0          0

This is an 64 bit machine, the "concentrator".

It looks like use all, the 4G ram as "lowmem".
If i replace the cpu on my nodes to 64bit capable ones, i can use all the
memory as buffer-cache? :-)

Cheers,
Janos



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