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Re: [Help-smalltalk] .. surprising results

From: Paolo Bonzini
Subject: Re: [Help-smalltalk] .. surprising results
Date: Wed, 22 Sep 2004 09:00:44 +0200
User-agent: Mozilla Thunderbird 0.5 (Windows/20040207)

I just ran for run, and got the following figures, on my
Pentium IV 2.8Ghz 512Kb cache machine:

     72,644,721 bytecodes/sec; 2,460,329 sends/sec
     66,832,006 bytecodes/sec; 2,447,278 sends/sec
     71,438,537 bytecodes/sec; 2,187,121 sends/sec

These are 3 times the reported values for a Pentium II 300Mhz machine.
It makes me wonder if there is some machine tick (which is constant)
related performance constraint in the vm.

The Pentium 4 is absolutely not suited to bytecode interpretation. Indeed the faster VM is almost 50% faster on the Pentium 4 because it executes fewer bytecodes (longer traces in the P4's trace cache and fewer stalls due to indirect jumps).

Most of the mprotect's are outside the inner loop (GC's happen outside it).

Am I wrong? should I not expect a more significant improvement from a
machine an order of magnitude faster mhz + bus etc, + paolo's 20% faster
VM ?
I would have tried with --enable-jit, but:

Thanks, I'll look into this.


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