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From: Brian Barrett (bbarrett_at_[hidden])
Date: 2007-07-10 14:37:13


On Jul 10, 2007, at 11:40 AM, Scott Atchley wrote:

> On Jul 10, 2007, at 1:14 PM, Christopher D. Maestas wrote:
>
>> Has anyone seen the following message with Open MPI:
>> ---
>> warning:regcache incompatible with malloc
>> ---
>>
>> <snip>
>>
>> ---
>>
>> We don't see this message with mpich-mx-1.2.7..4
>
> MX has an internal registration cache that can be enabled with
> MX_RCACHE=1 or disabled with MX_RCACHE=0 (the default before MX-1.2.1
> was off, and starting with 1.2.1 the default is on). If it is on, MX
> checks to see if the application is trying to override malloc() and
> other memory handling functions. If so, it prints the error that you
> are seeing and fails to use the registration cache.
>
> Open MPI can use the regcache if you set MX_RCACHE=2. This tells MX
> to skip the malloc() check and use the cache regardless. In the case
> of Open MPI, this is believed to be safe. That will not be true for
> all applications.
>
> MPICH-MX does not manage memory, so MX_RCACHE=1 is safe to use unless
> the user's application manages memory.

Scott -

I'm having trouble getting the warning to go away with Open MPI.
I've disabled our copy of ptmalloc2, so we're not providing a malloc
anymore. I'm wondering if there's also something with the use of
DSOs to load libmyriexpress? Is your belief that MX_RCACHE=2 is safe
just for the BTL or for the MTL as well?

Brian

-- 
   Brian W. Barrett
   Networking Team, CCS-1
   Los Alamos National Laboratory