[GHC] #15049: NUMA not detected on Win10 with AMD Ryzen Threadripper

[GHC]

#15049: NUMA not detected on Win10 with AMD Ryzen Threadripper
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        Reporter:  kanetw          |                Owner:  (none)
            Type:  bug             |               Status:  new
        Priority:  normal          |            Milestone:  8.6.1
       Component:  Runtime System  |              Version:  8.4.1
      Resolution:                  |             Keywords:
Operating System:  Windows         |         Architecture:  x86_64 (amd64)
 Type of failure:  None/Unknown    |            Test Case:
      Blocked By:                  |             Blocking:
 Related Tickets:                  |  Differential Rev(s):
       Wiki Page:                  |
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Comment (by kanetw):

 I think I found the reason:
 win32/OSMem.c
 {{{
 bool osNumaAvailable(void)
 {
     return osNumaNodes() > 1;
 }

 uint32_t osNumaNodes(void)
 {
     /* Cache the amount of NUMA values. */
     static ULONG numNumaNodes = 0;

     /* Cache the amount of NUMA nodes. */
     if (!numNumaNodes && !GetNumaHighestNodeNumber(&numNumaNodes))
     {
         numNumaNodes = 1;
     }

     return numNumaNodes;
 }
 }}}
 Looks like a off by one. GetNumaHighestNodeNumber is 0 on non-NUMA
 systems, and >0 on NUMA systems, but osNumaAvailable() checks for >1

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15049#comment:2>
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