Thanks Oliver; I'm getting a welcome 1% increase in performance.

GTX690
GPUSieveProcessSize=8
GPUSieveSize=128
GPUSievePrimes=107500

Now, looks like mfaktc has been immortalized by Andy Warhol! ;-)

[QUOTE=Mark Rose;395704]Also, I noticed this is still in the mfaktc.ini file at least in the Linux source download:

# GPU sieving is supported on GPUs with compute capability 2.0 or higher.
# (e.g. Geforce 400 series or newer)[/QUOTE]

Good catch, this is a bug somehow!
I would say a minor bug so don't expect a 0.21p1 just because of this.

Oliver

Renaming of the worktodo.txt file disappeared from the ini file. Is it gone from the features too? Something to do with the new ".add" feature? It would be a pity, because some of us use different worktodo files, changing the ini (possible with a batch) when we want the card only partial busy, etc.

Hi,

yes, worktodo.txt is now static, just like all the other files mfaktc.exe accesses. Last part of the first sentence is the reason why I did so.
Can you simple rename the different worktodo files with the logic which renames the mfaktc.ini file?

Oliver

Yes, we can live with it.
Just installed it and it is faster for me too, about 1% faster on a Titan and on the 580 which paints the screens, and bout 2% faster on the other 580's, all with the default gpu sieve primes (the 82k and some). Didn't tune yet, 2:00 AM here... maybe during the weekend.
Good job! :tu:

Uh-oh: Symantec's Norton Power Eraser thinks that MFAKTC is bad:

I'm not worried, but I wonder what might be leading NPE to consider it "untrustworthy."

Rodrigo

[QUOTE=Rodrigo;395918]Uh-oh: Symantec's Norton Power Eraser thinks that MFAKTC is bad:

I'm not worried, but I wonder what might be leading NPE to consider it "untrustworthy."

Rodrigo[/QUOTE]

Norton Internet Security gave the same complaint. I believe that such flags are based on the application being unknown in the Norton Community database. There are no direct heuristics indicating malware aside from the file having very restricted distribution.

I just tried 0.21 on a small exponent (~500K) from 61 to 62 bits. To my surprise, the usage of CPU was virtually 0%, as if the sieving was being entirely performed on the GPU. The usage of GPU was consistently at 99%, which is also in line with sieving performed on it According to the post by Oliver presenting 0.21 to the community, I thouhgt that feature (GPU Sieving for bit levels lower than 64 bits) was to be implemented on version 0.22 only. Is that so, or something changed the plans?

[I]EDIT: I just went back and couldn´t find the reference to sieving for < 64 bits implementation on ver 0.22 anymore. So probably it was already foreseen as a 0.21 feature and the reference was edited out of the post by the OP or some watchful moderator...
[/I]
All in all, another great improvement. Thanks a lot!

Hi,

there is GPU sieving below 2[SUP]64[/SUP] in mfaktc 0.21 BUT this is not really a [U]fast[/U] kernel. Should be the [I]75bit_mul32_gs[/I] kernel. I guess you'll see a nice speed increase when going above 2[SUP]64[/SUP] when it switches to some barrett based kernel. If it is a modern GPU I *guess* you'll see 80-95% more throughput when going above 2[SUP]64[/SUP].

To be honest: I won't focus much on performance below 2[SUP]64[/SUP].

Oliver

[QUOTE=TheJudger;395930]

To be honest: I won't focus much on performance below 2[SUP]64[/SUP].

Oliver[/QUOTE]

Fair enough, I appreciate that. It´s already a good thing 0.21 allows <1M exponents and the sieving for lower bit levels, even if the performance is not really tuned. In fact, I have also used 0.21 for higher bit levels, and the throughput is way better.

To give an idea: (GTX 560Ti, GPU@900MHz)

500 k , 61-62 bits: 130 GHz-d/d

500 k, 62-63 bits: 205 GHZ-d/d

500 k, 64-65 bits: 357 GHz d/d

I´ll probably run some more benchies and keep you posted.