Re: Memory issues with Opteron 6220

[Ingo Molnar <mingo@elte.hu>]

* Eric Dumazet <eric.dumazet@gmail.com> wrote:

> Le jeudi 09 février 2012 à 09:33 +0100, Ingo Molnar a écrit :
> > * Anders Ossowicki <aowi@novozymes.com> wrote:
> > 
> > > Hey,
> > > 
> > > We're seeing unexpected slowdowns and other memory issues with a new system.
> > > Enough to render it unusable. For example:
> > > 
> > > Error: open3: fork failed: Cannot allocate memory
> > > 
> > > at times where there's no real memory pressure:
> > >                    total       used       free     shared    buffers     cached
> > >       Mem:     132270720  131942388     328332          0     299768  103334420
> > >       -/+ buffers/cache:   28308200  103962520
> > >       Swap:      7811068      13760    7797308
> > >
> > > [...]
> > 
> > > The system is a Dell Poweredge R715, with two eight-core 
> > > Opteron 6220 processors and 128G of memory. We have several 
> > > similar systems, such as the one this should replace: R715, 
> > > 2x8 core Opteron 6140, 128G memory, and they do not exhibit 
> > > any similar symptoms.
> > 
> > 130 MB of RAM visible to Linux isn't the expected bootup default 
> > indeed. Around 130 *GB* would be expected ...
> 
> Not sure what you mean, I see 128GB in the "free" output, as 
> expected.

Erm, yes. I plead temporary blindness!

So all RAM is visible properly. This error:

> > > Error: open3: fork failed: Cannot allocate memory

suggests allocation failure. How is that possible with so much 
RAM?

Thanks,

	Ingo