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Subject: Re: [OMPI devel] SM init failures
From: George Bosilca (bosilca_at_[hidden])
Date: 2009-03-30 13:34:29


Then it looks like the safest solution is the use either ftruncate or
the lseek method and then touch the first byte of all memory pages.
Unfortunately, I see two problems with this. First, there is a clear
performance hit on the startup time. And second, we will have to find
a pretty smart way to do this or we will completely break the memory
affinity stuff.

   george.

On Mar 30, 2009, at 13:24 , Iain Bason wrote:

>
> On Mar 30, 2009, at 12:05 PM, Jeff Squyres wrote:
>
>> But don't we need the whole area to be zero filled?
>
> It will be zero-filled on demand using the lseek/touch method.
> However, the OS may not reserve space for the skipped pages or disk
> blocks. Thus one could still get out of memory or file system full
> errors at arbitrary points. Presumably one could also get segfaults
> from an mmap'ed segment whose pages couldn't be allocated when the
> demand came.
>
> Iain
>
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