Newsgroups: comp.parallel
From: Suresh Kalathur <suresh@cs.brandeis.edu>
Subject: Maspar MP-2  Router vs rfetch
Organization: Brandeis University
Date: Fri, 23 Jun 1995 02:49:24 GMT
Message-ID: <3sda3k$d51@news.cs.brandeis.edu>


Hi 

   Here is an example with the 'router' and
   'rfetch' commands on the Maspar MP2
   written in MPL C.


    proc : 0 1 2 3 4 5 6 7 8 9  10 11 12 13 14 15
    pos  : 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 0
    ---------------------------------------------
    vec  : 0 1 2 3 4 5 6 7 8 9  10 11 12 13 14 15
             vec = router[pos].vec;
    vec  : 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 0
            Perfect
    ---------------------------------------------
    vec  : 0 1 2 3 4 5 6 7 8 9  10 11 12 13 14 15
             ss_rfetch(pos, &vec, &vec, sizeof(int));
    vec  : 1 2 3 5 5 6 7 9 9 10 11 13 13 14 15 1 
          Ha! Processors  3 7 11 15 have a wrong value
    ---------------------------------------------
    vec  : 0 1 2 3 4 5 6 7 8 9  10 11 12 13 14 15
             ss_rfetch(pos, &vec, &vec1, sizeof(int));
    vec1 : 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 0
            Perfect
    ---------------------------------------------

  I could see the wrong values fetched in symmetric
  positions. Is this a feature or ?

Suresh Kalathur
 suresh@cs.brandeis.edu

  
--
Suresh Kalathur               suresh@cs.brandeis.edu
Computer Science Dept         http://www.cs.brandeis.edu/~suresh
Brandeis University
Waltham, MA 02254


