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Subject: Re: [OMPI devel] SM init failures
From: Eugene Loh (Eugene.Loh_at_[hidden])
Date: 2009-03-30 19:01:33


Jeff Squyres wrote:

> On Mar 30, 2009, at 1:40 PM, Patrick Geoffray wrote:
>
>> > we will have to find a
>> > pretty smart way to do this or we will completely break the memory
>> > affinity stuff.
>>
>> I didn't look at the code, but I sure hope that the SM init code does
>> touch each page to force allocation, otherwise there is no memory
>> affinity stuff at all...
>
> Why not? The "owning" process can do the touch; then it'll be
> affinity'ed properly. Right?

So far as I can tell, the code has two mechanisms for memory placement.
One is to create a different mpool for each affinity pool. The second
is to have the correct owner perform the first touch. (It's not clear
to me that the first mechanism is working, makes sense, is necessary,
etc. I just don't know.) Anyhow, we do indeed want proper first touch
and the code seems to respect that.