[rvm-research] ImmixConstants MAX_COLLECTORS value

Hi all,

I just compiled a production build of Jikes RVM on my shiny new 32 core x86_64-linux box. RVM built ok but when I ran it with the DaCapo avrora benchmark it died on the first major GC, failing this assertion:

[snip]
  at [0x70e52ee4, 0x64ec6f56] Lorg/jikesrvm/mm/mmtk/Assert; _assert(Z)V at line 55
   at [0x70e52ee4, 0x64ec6f56] Lorg/mmtk/policy/immix/ImmixSpace; prepare(Z)V at line 139

The assertion in ImmixSpace.java line 139 is:

VM.activePlan.collectorCount() <= MAX_COLLECTORS

I checked MAX_COLLECTORS, which is set to 16 in 
MMTk/src/org/mmtk/policy/immix/ImmixConstants.java

I bumped the MAX_COLLECTORS value to 64, and now the benchmark completes successfully.

I guess this issue may trip up a number of unsuspecting people, especially as core counts are increasing. My question is, should we automatically generate the value for MAX_COLLECTORS using something like Linux nproc at source code generation time? Or at least, flag this issue somewhere sensible so people know what's happening?

Many thanks,
Jeremy

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http://www.dcs.gla.ac.uk/~jsinger

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