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SubjectRe: Fwd: kswapd issues + kernel 2.4.21-32.0.1.ELsmp
On Sat, Mar 31, 2007 at 01:11:29AM -0700, Pedram M wrote:
> Hi,
>
> I've seen this around, and have heard about it in forums and else-where,
> could somebody enlighten me with more information or with experiences
> they have had. Looks like kswapd begins to eat CPU dramatically till the
> box eventually locks up.

My experience with kswapd eating a lot of CPU tells that this particular
problem with Linux 2.4 manifests itself on this scenario:

* No swap is configured (we are blessed with RAM).

_AND_:

* A lot of memory is allocated (for my case: a lot of anonymous pages
used for applications).

Looking at this problem with kdb, I noticed that the CPU spends a lot
of time in swap_out(), even though there are no swap devices...

So...

mm/vmscan.c, replace swap_out with this:

static int swap_out(zone_t * classzone)
{
return 0;
}

Now, this might raise some eyebrows for those MM gurus reading this
mail but I assure you I've been doing this for a lot of time (and
a lot of machines) on 2.4.27, and it took care of my kswapd issues
quite nicely.

I hope it helps...

--
Dan Aloni
XIV LTD, http://www.xivstorage.com
da-x (at) monatomic.org, dan (at) xiv.co.il
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