Re: Misleading OOM messages

[Pavel Machek]

On Fri 2009-05-15 17:15:54, Christoph Lameter wrote:
> On Fri, 15 May 2009, Pavel Machek wrote:
> 
> > > Nope. If you have too little memory for your app then the kernel pages
> > > portions of the app out to disk. Thats is why you have a VM (VIRTUAL
> > > machine). The app is not running with physical memory.
> >
> > Try running your machine with mem=8M, then tell me how virtual memory
> > works.
> 
> Well that is of course not enough memory.

Ok, so in the end, there are two reasons for OOM:

1) Out of virtual memory.

   there's simply not enough ram+swap to fit the data. You go OOM.
   This seems to be common on small machines. 8M is pushing it, but
   64M ram + 64M swap + todays gnome would probably do that.

   And maybe the way to hint people would be printing 'out of
   _virtual_ memory'.

2) Something goes very wrong with reclaim

   this seems to be common on very  big machines you have experience
   with.

Perhaps 1 and 2 can be told appart by zero swap free in the 1) case?
And perhaps you can invent some better message for 2) case?
								Pavel
-- 
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(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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