Does Cray mpich have a 64 bit integer MPI variable?
<p>I am using cray-mpich/7.4.0. When I do</p>

<pre><code> printf("Size:%d",sizeof(MPI_UINT64_T));
</code></pre>

<p>It print 4 instead of 8. Why is that? The cluster machine is 64 bit for sure. </p>

<p>I have tried this with openmpi/1.10.2 on another cluster and that prints 8. </p>