[M3devel] optimization [ was Re: Performance issues with CM3 ]

[Mika Nystrom]

How would I know?  I'm trying to turn on profiling but it seems to be a
bit involved.  Involves re-building all the libraries?

(cm3 -profile seems to look for FreeBSD4p instead of plain FreeBSD4...)

     Mika

Tony Hosking writes:
>Hmm.  Interesting.  What about exception scopes?
>
>On 27 Apr 2009, at 11:17, Mika Nystrom wrote:
>
>> Tony Hosking writes:
>> ...
>>>> With lots of tweaks and adjustments, I now see my code running about
>>>> 100% slower under CM3 than the same code does under PM3 (on the
>>>> same machine).  This is including my typecase hacks, as described
>>>> earlier today.  I'm guessing most of it is the FreeBSD pthreads
>>>> implementation in libc_r + the calls to PushEFrame.
>>>
>> Yikes!  How much of this is module initialization (startup) time?
>>>
>>
>> Ok, I re-checked just to make sure.  As far as I know, exactly the  
>> same code,
>> no initialization overhead (program's already running):
>>
>> CM3:
>>
>>> (time-call (lambda()(make-standard-stuff "Example")))
>> 1.309586018207483
>>>
>>
>> PM3:
>>
>>> (time-call (lambda()(make-standard-stuff "Example")))
>> 0.5641579627990723
>>>
>>
>> Bear in mind this is pretty close to a worst-case test for the  
>> "delta" between
>> PM3 and CM3.  Lots of small procedures, lots of typecases.
>>
>> Well, actually, I can make it worse.  Turn on locking in the Scheme  
>> environments
>> (so that they could be used by multi-threaded interpreters):
>>
>> CM3:
>>
>>> (time-call (lambda()(make-standard-stuff "Example")))
>> 2.1610950572649017
>>>
>>
>> PM3:
>>
>>> (time-call (lambda()(make-standard-stuff "Example")))
>> 0.6010241508483887
>>>
>>
>> CM3 without my change to RTType:
>>
>>> (time-call (lambda()(make-standard-stuff "Example")))
>> 2.2972461158642545
>>>
>>
>> 250% slower.
>>
>> But it is very demanding on pthreads.  Lots of little procedures,
>> lots of typecases, lots of locking.  (No contention, though.)
>>
>>    Mika
>>
>> P.S. the code in question is a scheme-m3 stub generator; it's making
>> stub interfaces in the tests above.
>