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Subject: Re: Speedup?

Author: Slater Wold

Date: 05:14:31 09/06/02

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On September 06, 2002 at 01:41:25, Dave Gomboc wrote:

>On September 05, 2002 at 22:37:18, Slater Wold wrote:
>
>>On September 05, 2002 at 21:33:40, Dann Corbit wrote:
>>
>>>On September 05, 2002 at 21:29:09, martin fierz wrote:
>>>
>>>>On September 05, 2002 at 21:18:42, Slater Wold wrote:
>>>>
>>>>>Any comments/thoughts/ideas/suggestions welcome.
>>>>
>>>>great stuff slater!
>>>>what i'd like to see is not only an average speedup (defined as time ratio, not
>>>>nps ratio - i think that time ratio is what counts) as you give, but rather a
>>>>list of all 300 speedups you observed, so we can see how the values are
>>>>distributed (you gave 2 extreme examples) - or you can just give us the standard
>>>>error on the speedup. what would also be interesting is if you reran the 2 CPU
>>>>test (maybe more than once....), and recomputed the average, and looked how
>>>>variable the average speedup is over such a large number of test positions. i'd
>>>>think that at least the average should be fairly stable, but even that seems to
>>>>be unclear...
>>>
>>>By what means are you limiting the search?
>>>
>>>Did you set time in seconds or depth in plies or what?  It will make a very big
>>>difference on how we might interpret the results.
>>>
>>>Hash tables can share hits and mask speedup.
>>>
>>>Timed searches can suffer from the same effect.
>>>
>>>Depth in ply searches are probably the most reliable comparisons, but it is
>>>impossible to know which ply level is sensible since some problems may take
>>>weeks to reach ten plies and others may reach 32 plies in a few seconds.
>>>
>>>In short, the real difficulty here is designing the experiment.  Quite frankly,
>>>I don't know the best way to proceed.
>>
>>I understand what you're getting out, but I do not agree.  Simply because the
>>definition of "relative speedup" is "the ratio of the
>>serial run time of a parallel application for solving a problem on a
>>single processor, to the time taken by the same parallel application
>>to solve the same problem on n processors".  It's all about "run time" and less
>>about "run parameters".  IMO.
>>
>>As long as both runs were using the *same exact* settings, I think all would be
>>fair.
>>
>>
>>Also, I simply used 'st 60' in Crafty.  A *lot* of positions were thrown out
>>because a.) they were solved at root or b.) the search time was less than 60
>>seconds.
>
>Don't you want to be doing something like 'sd 10' and computing
>time(2cpu)/time(1cpu)?
>
>Dave

*I* don't think so.  Because the classic definition of "relative speedup" is
based on runtime.  Not depth.



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