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Re: Timing graphics in the real world

  • To: mathgroup at smc.vnet.net
  • Subject: [mg123009] Re: Timing graphics in the real world
  • From: Ralph Dratman <ralph.dratman at gmail.com>
  • Date: Sun, 20 Nov 2011 05:37:12 -0500 (EST)
  • Delivered-to: l-mathgroup@mail-archive0.wolfram.com
  • References: <201111191145.GAA18886@smc.vnet.net>

Thank you, Bobby. I understand that. Now how do I speed up the
graphics? I am prepared to spend $ if necessary! Or... maybe I am
asking this particular question in the wrong forum. If so... my
apologies. I don't wish to be a pest.

Ralph

On Sat, Nov 19, 2011 at 3:24 PM, DrMajorBob <btreat1 at austin.rr.com> wrote:
> A quote from Help:
>
> "AbsoluteTiming[expr] measures only the time involved in actually evaluating
> expr, not time involved in formatting the result."
>
> Graphics rendering occurs in the FrontEnd, not the Kernel, so AbsoluteTiming
> doesn't count it.
>
> Bobby
>
> On Sat, 19 Nov 2011 05:45:59 -0600, Ralph Dratman <ralph.dratman at gmail.com>
> wrote:
>
>> I am trying to find out why a piece of 3D graphics code takes a long
>> time when scaled up to a lot of little objects. For this purpose I
>> begin by timing ten runs of a small instance. Here's what my function
>> calls look like:
>>
>> noneOfThat[] :=
>>  Module[{}, {drawSolidCube[], drawSolidCube[], drawSolidCube[],
>>   drawSolidCube[], drawSolidCube[], drawSolidCube[], drawSolidCube[],
>>    drawSolidCube[], drawSolidCube[], drawSolidCube[]}]
>>
>> where SolidCube is actually not solid, but rather an aggregate of
>> about 20 cubelets per image in this first test case.
>>
>> AbsoluteTiming[noneOfThat[]]
>> {0.072105,  ...}
>>
>> or if you prefer,
>>
>> Timing[noneOfThat[]]
>> {0.071197,  ...}
>>
>> The timing answers are consistent within about 10% across several tries.
>> Nice.
>>
>> Just one problem: here in my universe, on a Core Duo Mac Mini at 2.4
>> GHz with about 2 GB of free memory, the actual process described above
>> takes about 10 seconds. The cores stay at around 50% usage (each)
>> while this is happening. Drawing is taking about 140 times longer than
>> Mathematica says!
>>
>> Next I try the same task with a 2x increase in linear size of the
>> cube, leading to an 8x increase in volume and number of objects, with
>> again 10 repetitions in straight-line Mathematica code.
>>
>> AbsoluteTiming then says 0.62970 while Timing says 0.574067, both in
>> the neighborhood of 8 times the earlier figures. Real-world time is
>> about 85 seconds, also in line with the 8x scaling.
>>
>> Again the processors seem to be about half busy, and once again it
>> takes about 140 times as long to do the real drawing as Mathematica
>> reports.
>>
>> I'm speculating all this means Mathematica is sending my graphics
>> hardware a bunch of asynchronous drawing calls while simultaneously
>> announcing, "Done!"
>>
>> I infer that a faster graphics card might make a world of difference.
>> To make that possible, I could switch to a Windows or Linux system if
>> necessary.
>>
>> If possible, I would like the new real-world drawing time to be at
>> least ten times better than the figures reported here.
>>
>> Comments, please? I would be particularly interested to learn about
>> any specific hardware that might improve the speed.
>>
>> Thank you very much.
>>
>> Ralph Dratman
>>
>
>
> --
> DrMajorBob at yahoo.com
>



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