About pass1 and pass2 on worker message

jxwleong · 2021-05-20, 06:12

Hi,
May I know what's the meaning of Pass1 and Pass2 in mprime?
Thanks

Quote:

[Worker #7 May 20 09:02] Test 1, 3200000 Lucas-Lehmer iterations of M172031 using FMA3 FFT length 8K, Pass1=128, Pass2=64.
[Worker #2 May 20 09:02] Test 1, 3200000 Lucas-Lehmer iterations of M172031 using FMA3 FFT length 8K, Pass1=128, Pass2=64.
[Worker #4 May 20 09:02] Test 1, 3200000 Lucas-Lehmer iterations of M172031 using FMA3 FFT length 8K, Pass1=128, Pass2=64.
[Worker #3 May 20 09:02] Test 1, 3200000 Lucas-Lehmer iterations of M172031 using FMA3 FFT length 8K, Pass1=128, Pass2=64.
[Worker #8 May 20 09:02] Test 1, 3200000 Lucas-Lehmer iterations of M172031 using FMA3 FFT length 8K, Pass1=128, Pass2=64.
[Worker #5 May 20 09:02] Test 1, 3200000 Lucas-Lehmer iterations of M172031 using FMA3 FFT length 8K, Pass1=128, Pass2=64.
[Worker #1 May 20 09:02] Test 1, 3200000 Lucas-Lehmer iterations of M172031 using FMA3 FFT length 8K, Pass1=128, Pass2=64.
[Worker #6 May 20 09:02] Test 1, 3200000 Lucas-Lehmer iterations of M172031 using FMA3 FFT length 8K, Pass1=128, Pass2=64.
[Worker #2 May 20 09:04] Self-test 8K passed!
[Worker #2 May 20 09:04] Test 1, 3200000 Lucas-Lehmer iterations of M163839 using FMA3 FFT length 8K, Pass1=128, Pass2=64.
[Worker #5 May 20 09:04] Self-test 8K passed!
[Worker #5 May 20 09:04] Test 1, 3200000 Lucas-Lehmer iterations of M163839 using FMA3 FFT length 8K, Pass1=128, Pass2=64.
[Worker #6 May 20 09:04] Self-test 8K passed!
[Worker #6 May 20 09:04] Test 1, 3200000 Lucas-Lehmer iterations of M163839 using FMA3 FFT length 8K, Pass1=128, Pass2=64.
[Worker #1 May 20 09:04] Self-test 8K passed!
[Worker #1 May 20 09:04] Test 1, 3200000 Lucas-Lehmer iterations of M163839 using FMA3 FFT length 8K, Pass1=128, Pass2=64.
[Worker #4 May 20 09:04] Self-test 8K passed!
[Worker #4 May 20 09:04] Test 1, 3200000 Lucas-Lehmer iterations of M163839 using FMA3 FFT length 8K, Pass1=128, Pass2=64.
[Worker #8 May 20 09:04] Self-test 8K passed!
[Worker #7 May 20 09:04] Self-test 8K passed!
[Worker #8 May 20 09:04] Test 1, 3200000 Lucas-Lehmer iterations of M163839 using FMA3 FFT length 8K, Pass1=128, Pass2=64.
[Worker #7 May 20 09:04] Test 1, 3200000 Lucas-Lehmer iterations of M163839 using FMA3 FFT length 8K, Pass1=128, Pass2=64.
[Worker #3 May 20 09:04] Self-test 8K passed!
[Worker #3 May 20 09:04] Test 1, 3200000 Lucas-Lehmer iterations of M163839 using FMA3 FFT length 8K, Pass1=128, Pass2=64.

retina · 2021-05-20, 06:15

The FFT multiply is split into multiple passes to break down the input into the FFT domain.

So the numbers you see are the "length" of the FFT for each pass.

kruoli · 2021-05-20, 07:20

You will also see that pass1 × pass2 = FFT length. Here it is 128 × 64 = 8192 (8K).

For most (all?) of the FFTs, there are multiple ways implemented how it might be divided into pass1 and pass2. There are usually somewhat different in speed. So for optimal computing or stress testing, Prime95/mprime tries to pick the "best" combination of these values.

jxwleong · 2021-05-21, 08:18

Get it now, thanks for the reply.

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2021-05-20, 06:15	#2
retina Undefined "The unspeakable one" Jun 2006 My evil lair 6,793 Posts	The FFT multiply is split into multiple passes to break down the input into the FFT domain. So the numbers you see are the "length" of the FFT for each pass.

2021-05-20, 07:20	#3
kruoli "Oliver" Sep 2017 Porta Westfalica, DE 661₁₆ Posts	You will also see that pass1 × pass2 = FFT length. Here it is 128 × 64 = 8192 (8K). For most (all?) of the FFTs, there are multiple ways implemented how it might be divided into pass1 and pass2. There are usually somewhat different in speed. So for optimal computing or stress testing, Prime95/mprime tries to pick the "best" combination of these values. Last fiddled with by kruoli on 2021-05-20 at 07:23 Reason: Additional information.

2021-05-21, 08:18	#4
jxwleong May 2021 2² Posts	Get it now, thanks for the reply.