Re: [rvm-research] How to record objects' read/write times

Thanks for Robin and Eliot 's heap!

This problem is complex and I don't make it clear. When I make
progress  ,I will post it here.

Now I'm working on some basic problems. And one of these problems is
how to confirm the nurser's size.( in GenImmix config )
I want to know the nursery(CopySpace)'s  exact size when the jikesrvm
is running.  So I insert some Log.writeln into the source code.


The  x86_64-linux.properties content is:

 13 target.arch=ia32
 14 target.os=Linux
 15 target.bootimage.code.address=0x64000000
 16 target.bootimage.data.address=0x60000000
 17 target.bootimage.rmap.address=0x67000000
 18 #target.max-mappable.address=0xb0000000
 19 target.max-mappable.address=0xa0000000
 20 target.address.size=32
 21 target.dll-ext=.so
 22 target.dll-prefix=lib
 23 target.jni-suffix=${target.dll-ext}
 24 target.arch.sse2=full
 25 target.arch.hw_fsqrt=true


I insert some Log.writeln in the CopyLocal.java

  public CopyLocal(CopySpace space) {
    super(space, true);

    //debug
    Log.writeln("In CopyLocal");
    Log.writeln("heap start:"+space.HEAP_START.toLong());
    Log.writeln("heap end:"+space.HEAP_END.toLong());
    Log.writeln("heap name:"+space.getName());
    Log.writeln("nursery space start:"+space.getStart().toLong());
    Log.writeln("nursery space extent:"+space.getExtent().toLong());
  }


I got the output as below:

   2 In CopyLocal
   3 heap start:1610612736  //0x6000 0000
   4 heap end:2684354560  // 0xA000 0000
   5 heap name:nursery
   6 nursery space start:2537553920  //0x9740 0000
   7 nursery space extent:146800640   //0x8c00 0000


The heap size is matching to the config in the x86_64-linux.properties
(1G) ; and the nursery size is 15% of the heap (140M),  just as the
NURSERY_VM_FRACTION = 0.15f;

And I know this is just  the limit of the heap size and nursery size
,not the exact size when the jikesRVM is running. So I insert some
other Log.writeln into the function " public void
collectionPhase(short phaseId)" in Gen.java , see below:


  public void collectionPhase(short phaseId) {  //Initialize?  every
phase need to be  initialized ??

    if (phaseId == SET_COLLECTION_KIND) {
      super.collectionPhase(phaseId);
      gcFullHeap = requiresFullHeapCollection(); // gcFullHeap is a
boolean, what's the flag use for ?
      return;
    }

    if (phaseId == PREPARE) {

    Log.writeln("In Gen.java/PREPARE");
    Log.writeln("nursery lowerbound:"+Options.nurserySize.getMinNursery());
    Log.writeln("nursery uppperbound"+Options.nurserySize.getMaxNursery());

    nurserySpace.prepare(true);

      if (traceFullHeap()){
        if (gcFullHeap) {
          if (Stats.gatheringStats()) fullHeap.set();
          fullHeapTime.start();
        }
        super.collectionPhase(phaseId);

        // we can throw away the remsets (but not modbuf) for a full heap GC
        remsetPool.clearDeque(1);
        arrayRemsetPool.clearDeque(2);
      }
      return;
    }

    if (phaseId == CLOSURE) {
    //debug
    Log.writeln("In Gen.java/CLOSURE");
    Log.writeln("nursery lowerbound:"+Options.nurserySize.getMinNursery());
    Log.writeln("nursery uppperbound"+Options.nurserySize.getMaxNursery());

      if (!traceFullHeap()) {
        nurseryTrace.prepare();
      }
      return;
    }

    if (phaseId == RELEASE) {

    Log.writeln("In Gen.java/RELEASE");
    Log.writeln("nursery lowerbound:"+Options.nurserySize.getMinNursery());
    Log.writeln("nursery uppperbound"+Options.nurserySize.getMaxNursery());


      nurserySpace.release();
      switchNurseryZeroingApproach(nurserySpace);
      modbufPool.clearDeque(1);
      remsetPool.clearDeque(1);
      arrayRemsetPool.clearDeque(2);
      if (!traceFullHeap()) {
        nurseryTrace.release();
      } else {
        super.collectionPhase(phaseId);
        if (gcFullHeap) fullHeapTime.stop();
      }
      nextGCFullHeap = (getPagesAvail() < Options.nurserySize.getMinNursery());
      return;
    }

    super.collectionPhase(phaseId);
  }



When I run :  rvm

the output is  matching  to the default config :

2685 In Gen.java/PREPARE
2686 nursery lowerbound:512      // 2MB
2687 nursery uppperbound8192   // 32MB

2085 In Gen.java/CLOSURE
2086 nursery lowerbound:512
2087 nursery uppperbound8192

2694 In Gen.java/RELEASE
2695 nursery lowerbound:512
2696 nursery uppperbound8192


And I know this is only the config of the option ,not the exact
nursery size. It's just the upper bound and lower bound.

When I run : rvm -X:gc:fixedNursery=10m  -jar dacapo-9.12-bach.jar h2

The output is :

1143 In Gen.java/CLOSURE
1144 nursery lowerbound:2560   // 10MB
1145 nursery uppperbound2560

1110 In Gen.java/RELEASE
1111 nursery lowerbound:2560
1112 nursery uppperbound2560

Yeah, Now the option of the nursery size is fixed 10MB.

My questions are :

1) I want to know how do the default  parameters pass to the PagesOption.value ?

I insert Log.writln into the NurserySize and  FixedNursery 's
constructor ,but print nothing ! And just as above, The
Options.nurserySize.getMinNursery() output is the default parameters.
So I think the object  fixedNursery must be built.


  public NurserySize() {

    //debug
    Log.writeln("In NurserySize.java:Init NurserySize");

    boundedNursery = new BoundedNursery();
    fixedNursery = new FixedNursery(boundedNursery);
  }


  public FixedNursery(BoundedNursery boundedNursery) {
    super(Options.set, "Fixed Nursery",
        "Fix the minimum and maximum size of the nursery to this value",
        Plan.DEFAULT_MIN_NURSERY);
    this.boundedNursery = boundedNursery;

    //debug
    Log.writeln("In fixedNursery");
    Log.writeln("Plan.DEFAULT_MIN_NURSERY"+Plan.DEFAULT_MIN_NURSERY);
    Log.writeln("Plan.DEFAULT_MIN_NURSERY"+Plan.DEFAULT_MIN_NURSERY);
  }



2) If I want to know the exact size of the nursery (GenImmix), Where
can I insert the Log.writeln ?


Thank you very much.



On Tue, May 12, 2015 at 12:35 PM, Robin Garner <[email protected]> wrote:
> On 11/05/15 17:53, 王晨曦 wrote:
>> Hi,every one
>>
>>    I want to record objects' read and write times. As far as I know,
>> the Write Barrier is inserted before every Pointer update( object
>> assignment ), so I can modify the Write Barrier to record the
>> reference  times of the source object. But I know the reference times
>> is not equal to the write times of the   source object. Such as:
>>
>> class a{
>>    ........
>> }
>>
>> class b{
>>
>> a test =new a();
>>
>> double array_double[ ];
>> int   array_int[];
>>
>> ....
>> }
>>
>>
>> and the write barrier will only be inserted before the: (Is this right ?)
>>
>> b.test=a ; //pointer update
>>
>> but these assignment below will be ignored. But I think these
>> assignments will contribute the main read/write times.
>>
>> for(i=0;i<Const;i++)
>>     array[i]=...
>>     array_int[i]===
>>
>
> If you look at the MutatorContext class you will see that there is not
> just one write barrier, but one per type plus a couple of special cases,
> so there should be opportunities to instrument every field access.
>
> I can't emphasize Eliot's point (3) enough: be very careful of the code
> you invoke in a barrier.  You need to be certain you don't trigger
> another barrier, and if you are instrumenting all types you must use the
> methods in org.mmtk.vm.Barriers to do *all* heap writes.
>
> Regards,
> Robin
>
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-- 
ChenXi.Wang
ICT.CAS China

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