From: Andrew Morton <akpm@osdl.org>
To: Christoph Lameter <clameter@sgi.com>
Cc: Linus Torvalds <torvalds@osdl.org>,
Aucoin <aucoin@houston.rr.com>,
'Nick Piggin' <nickpiggin@yahoo.com.au>,
'Tim Schmielau' <tim@physik3.uni-rostock.de>,
Linux Memory Management List <linux-mm@kvack.org>
Subject: Re: la la la la ... swappiness
Date: Tue, 5 Dec 2006 12:02:56 -0800 [thread overview]
Message-ID: <20061205120256.b1db9887.akpm@osdl.org> (raw)
In-Reply-To: <Pine.LNX.4.64.0612051130200.18569@schroedinger.engr.sgi.com>
On Tue, 5 Dec 2006 11:32:21 -0800 (PST)
Christoph Lameter <clameter@sgi.com> wrote:
> On Tue, 5 Dec 2006, Linus Torvalds wrote:
> > On Tue, 5 Dec 2006, Christoph Lameter wrote:
> > > We do not support swapping / reclaim for huge pages.
> >
> > Well, Louis doesn't actually _want_ swapping or reclaim on them. He just
> > wants the system to run well with the remaining 400MB of memory in his
> > machine.
> >
> > Which it doesn't. It just OOM's for some reason.
>
> If you take huge chunks of memory out of a zone then the dirty limits as
> well as the min free kbytes etc are all off. As a result the VM may
> behave strangely. F.e. too many dirty pages may cause an OOM since we do
> not enter synchrononous writeout during reclaim.
yes, it's quite possible that this setup would cause the page reclaim
arithmetic to go wrong.
But otoh, it's a very common scenario, and nobody has observed it before.
For example:
akpm2:/home/akpm# echo 4000 > /proc/sys/vm/nr_hugepages
Free memory on this box instantly fell from 7G down to ~250MB. It's now
happily chuggling its way through a `dbench 512' run.
But this is a 64-bit machine. Could be that there are problems on 32-bit.
--
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next prev parent reply other threads:[~2006-12-05 20:02 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <200612050641.kB56f7wY018196@ms-smtp-06.texas.rr.com>
2006-12-05 16:17 ` Linus Torvalds
2006-12-05 16:59 ` Andrew Morton
2006-12-05 17:41 ` aucoin, Andrew Morton
2006-12-05 18:31 ` Christoph Lameter
2006-12-05 18:44 ` Linus Torvalds
2006-12-05 19:32 ` Christoph Lameter
2006-12-05 20:02 ` Andrew Morton [this message]
2006-12-05 20:15 ` Christoph Lameter
2006-12-05 20:48 ` Andrew Morton
2006-12-05 20:59 ` Christoph Lameter
2006-12-05 21:39 ` Andrew Morton
2006-12-05 23:20 ` Christoph Lameter
2006-12-12 15:12 ` Aucoin
2006-12-05 20:52 ` Andrew Morton
2006-12-05 20:39 ` aucoin, Linus Torvalds
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