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Re: IDL Matrix Multiply and Dual-Core CPUs [message #60251 is a reply to message #60250]

Fri, 09 May 2008 11:20

Foldy Lajos
Messages: 268
Registered: October 2001

Senior Member

oops, I have written IDL 7 time to the ATLAS test. Corrected below.

lajos

I have run some tests on a quad-core Intel Core2 Q6600 / linux 64 bit
machine.

On Fri, 9 May 2008, s.haenger@gmail.com wrote:

Hi,

I have a Problem with IDL 7.0
We have to multiply large matrices. With some matrix sizes, the CPU
usage is 100% but for most of the matrices it is 50%. (I'm runnning it
on a Intel T7250 (Dual Core, 2GHz, 2MB L2 Cache))

The CPU System Variable is configured like this:
IDL> print, !CPU
{ 0 0 2 2
100000 0}

Now we do this:
matA = randomn(42, 2000, 2200)
matB = randomn(43, 2020, 2000)
matIdl = matA##matB

So now i've got a CPU usage of 100%

# of threads IDL 7 time
1 12.476210
2 6.5931890
3 5.2085290
4 4.9191489

it scales well for two cores, so the CPU usage should be near 100% for two
threads.

but with this:
matA = randomn(42, 2500, 2500)
matB = randomn(43, 2520, 2500)
matIdl = matA##matB

the cpu usage is around 50%-60%

# of threads IDL 7 time
1 22.034877
2 11.681226
3 9.7771089
4 9.3093379

again, CPU usage should be near 100% for two cores.

Just for comparison, ATLAS (http://math-atlas.sf.net) times:

# of threads ATLAS time
1 4.4285851
4 1.1784132

and

# of threads ATLAS time
1 7.8148808
4 2.1345751

regards,
lajos
>

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[Message index]

		Re: IDL Matrix Multiply and Dual-Core CPUs By: Pierre V. on Fri, 09 May 2008 11:34
		Re: IDL Matrix Multiply and Dual-Core CPUs By: s.haenger on Fri, 09 May 2008 11:28
		Re: IDL Matrix Multiply and Dual-Core CPUs By: Foldy Lajos on Fri, 09 May 2008 11:20
		Re: IDL Matrix Multiply and Dual-Core CPUs By: Foldy Lajos on Fri, 09 May 2008 11:16
		Re: IDL Matrix Multiply and Dual-Core CPUs By: Bringfried Stecklum on Fri, 09 May 2008 09:09
		Re: IDL Matrix Multiply and Dual-Core CPUs By: s.haenger on Tue, 20 May 2008 00:21
		Re: IDL Matrix Multiply and Dual-Core CPUs By: Karl[1] on Tue, 20 May 2008 11:19
		Re: IDL Matrix Multiply and Dual-Core CPUs By: s.haenger on Thu, 17 July 2008 01:42

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