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From: George Bosilca (bosilca_at_[hidden])
Date: 2007-07-14 14:42:39


If the OMPI_HAVE_THREAD_SUPPORT is not set the LIFO fall back to a
default version where atomic operations are not required. We can even
remove the dependency on the atomic.h header if the thread support is
not enabled.

Unfortunately, our shared memory device require the atomic operations
plus the memory barriers. Therefore, we cannot do anything more fine
grained (such as non-existence of atomic compare-and-swap disable
only the threading support and the non-existence of the memory
barrier disable only the shared memory support).

   george.

On Jul 14, 2007, at 1:27 PM, Brian Barrett wrote:

> On Jul 14, 2007, at 11:16 AM, George Bosilca wrote:
>
>> Instead of failing at configure time, we might want to disable the
>> threading features and the shared memory device if we detect that we
>> don't have support for atomics on a specified platform. In a non
>> threaded build, the shared memory device is the only place where we
>> need support for memory barrier. I'll look in the code to see why we
>> need support for compare-and-swap on a non threaded build.
>
> George -
>
> Disabling SM and threads if there's no atomic support would
> definitely be one option. The compare-and-swap is used by the LIFO
> used for ompi free lists.
>
> Brian
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