[Jikesrvm-researchers] dynamic pretenuring

[Jeremy S. <js...@cs...>]

Hi all,

I am doing some dynamic pretenuring tests using Jikes RVM 2.4.6, with
GenMS gc on IA32. The only existing RVM source code I could find to
guide me is from Jump/Blackburn/McKinley - "Dynamic Object Sampling for
Pretenuring" in ISMM 04.

I make a pretenuring decision in
com.ibm.JikesRVM.memoryManagers.mmInterface.MM_Interface
rather than in the MMTk code. This is because the inputs I use for the
pretenuring decision are not available in MMTk.

My scheme looks like this:

    boolean pretenure = ...; // pretenuring decision
    if (pretenure && allocator==Plan.ALLOC_DEFAULT) {
      allocator = Gen.ALLOC_MATURE;
    }

This decision comes at the start of the MM_Interface.allocateScalar()
method. Is this a reasonable way to hack pretenuring decisions into the
allocation process? Basically I want to divert long-lived objects from
the nursery space into the mature generation as efficiently as I can.

Thanks for any advice,
Jeremy