8k fft and L2 cache

pman · 2012-05-23, 12:02

I need clarification.

I want to test cpu by only running 8k fft for 12 hours, custom test.

my cpu is quad core with 64k L1 and 1024k L2 cache per core.

Is 8k fft enough to stress all of my L1/2 caches ?

I read in some places that 8k is all you need to test for cpu only...
I am not overclocking cpu. I am only undervolting, and then testing for stability.

Prime95 · 2012-05-23, 14:00

Each FFT element uses 8 bytes. Therefore, an 8K FFT uses 64KB data. There is some sin/cos data and code too, so I'm guessing total mem usage will be in the 120KB - 150KB area. This will easily fit in your L1/L2 caches. I'd think you can test FFT sizes from 8K to 32K.

Make sure you choose "in-place" testing.

2012-05-23, 12:02	#1
pman May 2012 1 Posts	8k fft and L2 cache I need clarification. I want to test cpu by only running 8k fft for 12 hours, custom test. my cpu is quad core with 64k L1 and 1024k L2 cache per core. Is 8k fft enough to stress all of my L1/2 caches ? I read in some places that 8k is all you need to test for cpu only... I am not overclocking cpu. I am only undervolting, and then testing for stability.

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2012-05-23, 14:00	#2
Prime95 P90 years forever! Aug 2002 Yeehaw, FL 2×4,079 Posts	Each FFT element uses 8 bytes. Therefore, an 8K FFT uses 64KB data. There is some sin/cos data and code too, so I'm guessing total mem usage will be in the 120KB - 150KB area. This will easily fit in your L1/L2 caches. I'd think you can test FFT sizes from 8K to 32K. Make sure you choose "in-place" testing.