Prime95 version 26.5

[Prime95]

Originally Posted by S34960zz

However, v26.5b2 mis-reports the processor speed at 3192 MHz; v25.11b2 gets it right at 1862 MHz. +++++

According to http://ark.intel.com/Product.aspx?id=43125 your max CPU speed is 3.2 GHz with one core running. So the new speed detection code worked - kinda.

[Prime95]

Build 3 is now available. If you have a multi-core hyperthreaded machine please test this version out. Let me know if it properly detects which logical cpus constitute a physical CPU. A message is output at startup.

If it isn't working, add the line "DebugAffinityScramble=1" to prime.txt and post the startup output.

[James Heinrich]

Seems to work properly for an i7-920:

Optimizing for CPU architecture: Core i3/i5/i7, L2 cache size: 256 KB, L3 cache size: 8 MB
Logical CPUs 0,1 form one physical CPU.
Logical CPUs 2,3 form one physical CPU.
Logical CPUs 4,5 form one physical CPU.
Logical CPUs 6,7 form one physical CPU.

And the LowMemWhileRunning issue is fixed!

Entering a period of low memory usage because C:\PROGRAM FILES\PTGUI\PTGUI.EXE is running.
Entering a period of low memory usage because C:\PROGRAM FILES\ADOBE\ADOBE PHOTOSHOP CS5 (64 BIT)\PHOTOSHOP.EXE is running.

[drh]

Works on my Quad Core X5355

Optimizing for CPU architecture: Core 2, L2 cache size: 4 MB
Logical CPUs 0,1 form one physical CPU.
Logical CPUs 2,3 form one physical CPU.
Logical CPUs 4,5 form one physical CPU.
Logical CPUs 6,7 form one physical CPU.

[drh]

Also works on my i7 Q720 Quad Core

Optimizing for CPU architecture: Core i3/i5/i7, L2 cache size: 256 KB, L3 cache size: 6 MB
Logical CPUs 0,1 form one physical CPU.
Logical CPUs 2,3 form one physical CPU.
Logical CPUs 4,5 form one physical CPU.
Logical CPUs 6,7 form one physical CPU.

[drh]

On my i7 machine, I just noticed my worker windows have the following lines in them ...

[Feb 18 19:05] Setting affinity to run worker on logical CPUs 0,1,2,3,4,5,6,7,31
[Feb 18 19:05] Setting affinity to run helper thread 1 on logical CPUs 0,1,2,3,4,5,6,7,31
[Feb 18 19:05] Resuming primality test of M49025983 using Core2 type-3 FFT length 2560K, Pass1=640, Pass2=4K, 2 threads
[Feb 18 19:05] Iteration: 23493594 / 49025983 [47.92%].

On my X5355 machine, I'm running 8 worker windows, and the CPU's match the worker windows.

[Prime95]

Originally Posted by James Heinrich

And the LowMemWhileRunning issue is fixed!

Alas, I did nothing to fix this. I could not reproduce the problem. It is a subtle bug, sure to reveal itself again at a later date.

[engracio]

Originally Posted by Prime95

This is a side effect of a bug fix in 26.4. I've coded up a fix for 26.5 build 3.

Upgraded to 26.5b3 and downloaded new wu. Worktodo.txt was updated properly when P-1 completed for a PRP test.

Thanks.

e

[Prime95]

Originally Posted by drh

On my i7 machine, I just noticed my worker windows have the following lines in them ...

[Feb 18 19:05] Setting affinity to run worker on logical CPUs 0,1,2,3,4,5,6,7,31
[Feb 18 19:05] Setting affinity to run helper thread 1 on logical CPUs 0,1,2,3,4,5,6,7,31

It looks like you have 8 worker windows each with a helper thread (16 threads total). This is very non-optimal. You likely better off just running 4 worker windows with no helper threads.

I'll investigate the mysterious cpu 31

[drh]

Sorry, more specifically, on my i7, I'm running 4 worker windows, each with a helper, (8 threads total), not 8 windows with 8 helpers. This can be seen by my post #71.

[Prime95]

Originally Posted by drh

Sorry, more specifically, on my i7, I'm running 4 worker windows, each with a helper, (8 threads total), not 8 windows with 8 helpers. This can be seen by my post #71.

Did you set the affinity for each thread to "run on any cpu"? That is the only explanation I have for the output you are seeing. (I've coded up a fix for the CPU #31 bug).

Two things you should do to try and get better throughput:

1) See if you get better timings with smart-affinity rather than run-on-any-CPU
2) See if you get better timings by not using a helper thread for each worker.