Re: How to benchmark memory managers?

>> We use exact object reachability traces [27, 28] as an oracle to 
>> indicate when objects should be deallocated. By implementing this 
>> oracle inside a detailed architectural simulator, we can execute and 
>> precisely measure unaltered Java applications as if they were written 
>> using explicit memory management.
> 
> by using an oracle, you eliminate the cost of the explicit management 
> that a programmer using explicit memory management would have had to 
> implement in order to determine when objects become garbage. Thus any 
> cost of explicit destruction or reference counting which may have to be 
> done is not accounted for. So I think this methodology is biased since 
> it completely eliminates the cost on one side that is being counted on 
> the other.

As we describe in the paper, the system inserts calls to free whenever the
oracle (object reachability trace) determines that an object can be deallocated.
  Because the programs are run in a simulator, I capture the full cost of these
deallocation calls without adding any overhead for the oracle.  Since the
results in our paper include the full costs of both explicit and implicit memory
management, we stand by our conclusions.

Matthew Hertz
[email protected]