[mpich-discuss] Using 32 bit as rank

[wei huang]

Hi list,

We here are trying to run mvapich2, which is based on mpich2-1.0.7, on
more than 32k processes. However, we find that MPIDI_Message_match
structure uses only int16_t as the rank. This is not enough for job larger
than 32k. It looks like the follow change that uses int32_t for rank is
needed to scale. Would you consider integrate this change in future mpich2
releases? Thanks.

Index: src/mpid/ch3/include/mpidpre.h
===================================================================
--- src/mpid/ch3/include/mpidpre.h      (revision 2891)
+++ src/mpid/ch3/include/mpidpre.h      (revision 2892)
@@ -65,7 +65,7 @@
 typedef struct MPIDI_Message_match
 {
     int32_t tag;
-    int16_t rank;
+    int32_t rank;
     int16_t context_id;
 }
 MPIDI_Message_match;


Regards,
Wei Huang

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