Prime95 version 27.7 / 27.9

[Rodrigo]

And here's the file for 27.9 (only one attachment per post allowed).

[flashjh]

Originally Posted by Rodrigo

So, I'm not sure what the benefit of 27.9 is supposed to be over 27.7. I'm probably doing something wrong...?

None expected, see here.

[Rodrigo]

Originally Posted by flashjh

None expected, see here.

Thanks -- so then the improvements have to do with avoiding errors when using HT, rather than with improvements in per-iteration times.

Remarkably, when using 27.7 on the i5-3210M if I set two workers each to use two CPUs for their own exponents instead of one CPU apiece, the total CPU load jumps to 100% but LL per-iteration times stay the same.

I'll have to go back and see how the i7-3770 handles this; my recollection is that the times get lower (they improve) if you assign more than one CPU to the same worker.

Rodrigo

[TheJudger]

Originally Posted by TheJudger

Xyzzy: yepp, I think this has to do with multithreading, too.

I'm doing some multithreaded P-1 (one worker per mprime process, multiple mprime processes per machine), everytime I add new work via worktodo.add I've to check whether the workers keep going or end in a endless loop (two different symptoms ^*1).

• 1 thread per worker: never happened
• 2 threads per worker: very, very rare
• 4 threads per worker: sometimes
• 8 threads per worker: often (>80%)

While mprime is running this can happen when starting a new exponent (start stage #1) or when switching from stage #1 to stage #2 (start stage #2), too.

Linux, mprime 27.7 64bit, 1 thread per core, running on a network share (NFS).
This happens with AVX code (Sandy Bridge), I can't exactly remember about SSE code.

I've the feeling that it happens more often on faster CPU.

Oliver

^*1

• endless loop: "SUMOUT error occurred"; wait 5 minutes
• endless loop: "Possible roundoff error (<some number>), backtracking to last save file."

So far this didn't occur with mprime 27.9.

Oliver

[koekie]

On one of my machines with i5-2400 proc AVX is (no longer) detected in version 27.9 (64 bit) on another machine with same proc AVX is detected in 27.9 as is AVX seen in CPU-Z. Is there an undoc.txt option to force AVX codepath?

[Prime95]

Originally Posted by koekie

On one of my machines with i5-2400 proc AVX is (no longer) detected in version 27.9 (64 bit) on another machine with same proc AVX is detected in 27.9 as is AVX seen in CPU-Z. Is there an undoc.txt option to force AVX codepath?

Yes, CPUSupportsAVX=1

[LaurV]

Small nitpicking:

In the last version of undoc.txt there is a copy/paste error:

Originally Posted by undoc.txt

You can have the program output residues every n iterations. The default value is the InterimFiles value.

it should read as "InterimResidues". [edit, in fact the second sentence can be at all eliminated, to be in line with the above and below paragraphs]

[Prime95]

Originally Posted by LaurV

it should read as "InterimResidues".

Actually, this is correct. If you set InterimFiles, InterimResidues is also set.

[bcp19]

I'm still having problems with my 2500k erroring out when trying to contact the server. It's the same for both the GIMPS server and when I try using the proxy at GPU72. I talked to chalsall about noticing assignments that 'allocated' to it but aren't in the worktodo, and have figured out that my system will get a send request ouit for a new assignment then crash before receiving it. There seems to be nothing I can do as it likely is an inherent flaw in the BIOS for this motherboard that causes the crash. I have automatic talking to Primenet shutoff since P95 only crashing when trying to communicate.

My question though, is it possible to somehow manually report results so the this system gets credit for it? The ones I have submitted so far, even though I include the (UID: bcp19/Main-2500k) it credits it to Manual Testing.

If the above question is no, can P95 be set to NOT delete the final save file upon determining an exponent is composite? I looked all through undoc.txt and trying searching the forum (I don't seem to be able to narrow the search enough to find an answer) so any help with this is appreciated.

[chalsall]

Originally Posted by bcp19

I'm still having problems with my 2500k erroring out when trying to contact the server. It's the same for both the GIMPS server and when I try using the proxy at GPU72. I talked to chalsall about noticing assignments that 'allocated' to it but aren't in the worktodo, and have figured out that my system will get a send request ouit for a new assignment then crash before receiving it.

Very interesting...

Another user was having a very similar issue. But his was a bit more complex. Sometimes his machine would get an assignment from the GPU72 proxy, but then immediately ignore the proxy settings and talk directly to Primenet seconds later.

Other times, the client would talk through the proxy for several days, and then suddenly ignore the proxy.

The user in question didn't have control of the firewall, so we couldn't debug this further. But your information suggests this might be a bug with the Prime95/mprime client.

[bcp19]

Originally Posted by chalsall

Very interesting...

Another user was having a very similar issue. But his was a bit more complex. Sometimes his machine would get an assignment from the GPU72 proxy, but then immediately ignore the proxy settings and talk directly to Primenet seconds later.

Other times, the client would talk through the proxy for several days, and then suddenly ignore the proxy.

The user in question didn't have control of the firewall, so we couldn't debug this further. But your information suggests this might be a bug with the Prime95/mprime client.

I don't think it is P95. When the program crashes on me, I restart it about 5-10 times before it stops crashing and runs(I'm thinking when it lasts long enough to finish talking to the server). From the assignments I saw on GPU72, it's apparent during these restarts that the program lasts long enough to request a new assignment 2-3 times before it lasts long enough to accept the response and continue running.
When I was running the 332M exp, I had the program set to only talk to primenet every 7 days cause it would crash too often otherwise and I hated losing several hours of work time for each crash. After having switched to 7 day reports, P95 would report anywhere from 1-4 times before crashing (1 week to 1 month give or take).
Since completing that exp, I first started doing DCs then switched to P-1 until I realized they finished too quickly and the program crashed too often. To offset this, I switched to LL and finally decided to stop it from talking to primenet and just manually report the results.