[Vm-dev] Performance of primitiveFailFor: and use of primFailCode

[Igor Stasenko]

On 24 May 2011 14:00, David T. Lewis <lewis at mail.msen.com> wrote:
>
> On Tue, May 24, 2011 at 10:46:02AM +0200, Igor Stasenko wrote:
>>
>> >
>> > No mistake, the performance problem was real.
>> >
>> > Good news - I found the cause. Better news - this may be good for a
>> > performance boost on StackVM and possibly Cog also.
>> >
>> > The performance hit was due almost entirely to InterpreterPrimitives>>failed,
>> > and perhaps a little bit to #successful and #success: also.
>> >
>> > This issue with #failed is due to "^primFailCode ~= 0" which, for purposes
>> > of C translation, can be recoded as "^primFailCode" with an override in
>> > the simulator as "^primFailCode ~= 0". This produces a significant speed
>> > improvement, at least as fast as for the original interpreter implementation
>> > using successFlag.
>> >
>> > I expect that the same change applied to StackInterpreter may give a similar
>> > 10% improvement (though I have not tried it). I don't know what to expect
>> > with Cog, but it may give a boost there as well.
>> >
>> > Changes attached, also included in VMMaker-dtl.237 on SqueakSource.
>> >
>> > Dave
>> >
>> >
>> >
>>
>> added to http://code.google.com/p/cog/issues/detail?id=45
>
> Thanks Igor.
>
>>
>> it is strange that such small detail  could make a lot of difference in speed.
>
> Yes, I was very surprised to see it also. It will be interesting to see
> if it has a similar effect for StackInterpreter. I probably will not have
> time to check this for a while, so if you try it please let us know
> what you find.
>

What you using to measure difference in speed?

> Dave
>
>



-- 
Best regards,
Igor Stasenko AKA sig.