There is a setting on the PrimeGrid preferences page called "GeneferCUDA Block Size". This can be used to vary the kernel size within GeneferCUDA.

For any specific computer, there is a particular value of the block size that produces the fastest calculations at each value of n. This optimal value is likely to be different for the Short work units and the Long (World Record) work units.

Besides changing the speed of the calculation, making this number larger generally reduces the amount of CPU usage, but may increase screen lag.

Decreasing this number may help with screen lag, but may increase CPU usage.

The default value is zero, which lets Genefer choose the best value. Under Windows, this value is 7 for the short (N=524288) work units and 8 for the long (World Record, N=4194304) work units. The default values for both Linux and Mac are 7 for the short work units and 9 for the long work units.

Usually, there will be no need to change this value. However, as we start searching the larger N values we will be working in an environment that is new, and it may be necessary to adjust these values. Therefore, it may be beneficial for this setting to be easily adjustable.

EDIT: Updated with more up to date information about the effects of changing the block size.
____________
Please do not PM me with support questions. They will usually go unanswered. Ask on the forums instead. Thank you!

My lucky number is 75898^524288+1

http://www.primegrid.com/result.php?resultid=339565550

Here's the first wu I've run since I changed the block size to 10. From what I can see there's absolutely no difference but then I'm not sure I changed the block size enough or what I need to be looking at on the unit. It's also possible the older wu's didnt take advantage of the block size. If 10 is the default size for the unit then I see why it made no difference.

So, suggestions on block sizes to try?

Raising the setting above 8 might show a reduction in CPU usage, but you're not going to get the app to run much faster than it already is since the utilization is pegged at 99% right now.

In any event, the setting doesn't do anything until 1.05 gets released.

The primary purpose for this is mitigating lag, if there turns out to be a problem at higher Ns.
____________
Please do not PM me with support questions. They will usually go unanswered. Ask on the forums instead. Thank you!

My lucky number is 75898^524288+1

After some testing, it seems that, at least for N=262144, valid values for the block size are 3 through 10. Anything outside of that causes an error. I'll have to wait for the WU to complete to be sure those values are OK.

If you enter a value outside of that range, the setting will be ignored.

It appears as if a value of 10 causes a slowdown of the GPU.

I'd recommend not changing the default setting, unless you're willing to do your own timing tests to see what works best on your hardware.

____________
Please do not PM me with support questions. They will usually go unanswered. Ask on the forums instead. Thank you!

My lucky number is 75898^524288+1

You might want to wait until 1.05 is released. The setting doesn't do anything with 1.04.
____________
Please do not PM me with support questions. They will usually go unanswered. Ask on the forums instead. Thank you!

My lucky number is 75898^524288+1

Rick, you inspired me to add a new command line option: "-b2 n", where n is the small n in a GFN, namely b^2^n+1.

GeneferCUDA-boinc 1.05 (CUDA3.2) based on GeneferCUDA 1.049 and Genefer 2.2.1
Copyright (C) 2001-2003, Yves Gallot (v1.3)
Copyright (C) 2009-2011, Mark Rodenkirch, David Underbakke (v2.2.1)
Copyright (C) 2010-2012, Shoichiro Yamada (CUDA)
Portions of this software written by Michael Goetz 2011-2012 (BOINC)
A program for finding large probable generalized Fermat primes.


Command line: GeneferCUDA-boinc-windows.exe -b2 18

Generalized Fermat Number Bench 2
SHIFT=3 710492^262144+1 Time: 27.7 ms/mul. Err: 5.00e-001 1533952 digits
SHIFT=4 710492^262144+1 Time: 7.06 ms/mul. Err: 4.21e-001 1533952 digits
SHIFT=5 710492^262144+1 Time: 1.89 ms/mul. Err: 4.21e-001 1533952 digits
SHIFT=6 710492^262144+1 Time: 1.05 ms/mul. Err: 4.21e-001 1533952 digits
SHIFT=7 710492^262144+1 Time: 1.04 ms/mul. Err: 4.21e-001 1533952 digits
SHIFT=8 710492^262144+1 Time: 1.11 ms/mul. Err: 4.21e-001 1533952 digits
SHIFT=9 710492^262144+1 Time: 1.76 ms/mul. Err: 4.21e-001 1533952 digits
SHIFT=10 710492^262144+1 Time: 3.83 ms/mul. Err: 4.21e-001 1533952 digits

So the next question is, do the timing results reflect real WUs? Let's do some real tests, but at N=8192 (because it's much faster). I got rid of SHIFT=3 because it's way too slow and takes too long to run.

GeneferCUDA-boinc 1.05 beta 1 (CUDA3.2) based on GeneferCUDA 1.049 and Genefer 2.2.1
Copyright (C) 2001-2003, Yves Gallot (v1.3)
Copyright (C) 2009-2011, Mark Rodenkirch, David Underbakke (v2.2.1)
Copyright (C) 2010-2012, Shoichiro Yamada (CUDA)
Portions of this software written by Michael Goetz 2011-2012 (BOINC)
A program for finding large probable generalized Fermat primes.


Command line: GeneferCUDA-boinc-windows.exe -b2 13

Generalized Fermat Number Bench 2
SHIFT=4 2009574^8192+1 Time: 349 us/mul. Err: 3.82e-001 51636 digits
SHIFT=5 2009574^8192+1 Time: 188 us/mul. Err: 3.82e-001 51636 digits
SHIFT=6 2009574^8192+1 Time: 161 us/mul. Err: 3.82e-001 51636 digits
SHIFT=7 2009574^8192+1 Time: 207 us/mul. Err: 3.82e-001 51636 digits
SHIFT=8 2009574^8192+1 Time: 403 us/mul. Err: 3.82e-001 51636 digits
GeneferCUDA-boinc.cu(193) : cufftSafeCall() CUFFT error: 6.

GeneferCUDA-boinc 1.05 beta 1 (CUDA3.2) based on GeneferCUDA 1.049 and Genefer 2.2.1
Copyright (C) 2001-2003, Yves Gallot (v1.3)
Copyright (C) 2009-2011, Mark Rodenkirch, David Underbakke (v2.2.1)
Copyright (C) 2010-2012, Shoichiro Yamada (CUDA)
Portions of this software written by Michael Goetz 2011-2012 (BOINC)
A program for finding large probable generalized Fermat primes.


Command line: GeneferCUDA-boinc-windows.exe -shift 8 -q 2009574^8192+1

Testing 2009574^8192+1...
maxErr during b^N initialization = 0.0000 (0.023 seconds).
2009574^8192+1 is a probable composite. (RES=ab752d28c1e60445) (51636 digits) (err = 0.2070) (time = 0:01:09) 23:31:48

GeneferCUDA-boinc 1.05 beta 1 (CUDA3.2) based on GeneferCUDA 1.049 and Genefer 2.2.1
Copyright (C) 2001-2003, Yves Gallot (v1.3)
Copyright (C) 2009-2011, Mark Rodenkirch, David Underbakke (v2.2.1)
Copyright (C) 2010-2012, Shoichiro Yamada (CUDA)
Portions of this software written by Michael Goetz 2011-2012 (BOINC)
A program for finding large probable generalized Fermat primes.


Command line: GeneferCUDA-boinc-windows.exe -shift 6 -q 2009574^8192+1

Testing 2009574^8192+1...
maxErr during b^N initialization = 0.0000 (0.030 seconds).
2009574^8192+1 is a probable composite. (RES=ab752d28c1e60445) (51636 digits) (err = 0.2070) (time = 0:01:10) 23:34:12

Mike, is this setting only active when you change the default value?
I see no switch in my client_state.xml-file.
____________
Best wishes. Knowledge is power. by jjwhalen

Mike, is this setting only active when you change the default value?
I see no switch in my client_state.xml-file.

It seems the benchmarks were fine. The -shift parameter wasn't working right, so all of the real runs were with the default shift value.

You might want to sit down for this one...

At the default value of 8:

Command line: GeneferCUDA-boinc-windows.exe -shift 8 -q 2009574^8192+1

Testing 2009574^8192+1...
maxErr during b^N initialization = 0.0000 (0.023 seconds).
2009574^8192+1 is a probable composite. (RES=ab752d28c1e60445) (51636 digits) (err = 0.2070) (time = 0:01:09) 23:31:48

Command line: GeneferCUDA-boinc-windows.exe -shift 6 -q 2009574^8192+1

Testing 2009574^8192+1...
maxErr during b^N initialization = 0.0000 (0.022 seconds).
2009574^8192+1 is a probable composite. (RES=ab752d28c1e60445) (51636 digits) (err = 0.2070) (time = 0:00:28) 07:01:18

Here are my benchmarks on a GTX 460 and a C2Q Q6600. YMMV.

Command line: GeneferCUDA-boinc-windows.exe -b2 18

Generalized Fermat Number Bench 2
SHIFT=4 710492^262144+1 Time: 7.01 ms/mul. Err: 4.21e-001 1533952 digits
SHIFT=5 710492^262144+1 Time: 1.9 ms/mul. Err: 4.21e-001 1533952 digits
SHIFT=6 710492^262144+1 Time: 1.05 ms/mul. Err: 4.21e-001 1533952 digits
SHIFT=7 710492^262144+1 Time: 1.04 ms/mul. Err: 4.21e-001 1533952 digits
SHIFT=8 710492^262144+1 Time: 1.1 ms/mul. Err: 4.21e-001 1533952 digits
SHIFT=9 710492^262144+1 Time: 1.74 ms/mul. Err: 4.21e-001 1533952 digits
SHIFT=10 710492^262144+1 Time: 3.81 ms/mul. Err: 4.21e-001 1533952 digits

Command line: GeneferCUDA-boinc-windows.exe -b2 19

Generalized Fermat Number Bench 2
SHIFT=4 577098^524288+1 Time: 13.9 ms/mul. Err: 2.01e-001 3020555 digits
SHIFT=5 577098^524288+1 Time: 3.62 ms/mul. Err: 2.01e-001 3020555 digits
SHIFT=6 577098^524288+1 Time: 2.08 ms/mul. Err: 2.01e-001 3020555 digits
SHIFT=7 577098^524288+1 Time: 1.96 ms/mul. Err: 2.03e-001 3020555 digits
SHIFT=8 577098^524288+1 Time: 2.04 ms/mul. Err: 2.01e-001 3020555 digits
SHIFT=9 577098^524288+1 Time: 2.48 ms/mul. Err: 2.01e-001 3020555 digits
SHIFT=10 577098^524288+1 Time: 4.54 ms/mul. Err: 2.01e-001 3020555 digits

Command line: GeneferCUDA-boinc-windows.exe -b2 20

Generalized Fermat Number Bench 2
SHIFT=4 468750^1048576+1 Time: 27.7 ms/mul. Err: 1.72e-001 5946413 digits
SHIFT=5 468750^1048576+1 Time: 7.05 ms/mul. Err: 1.64e-001 5946413 digits
SHIFT=6 468750^1048576+1 Time: 4.25 ms/mul. Err: 1.64e-001 5946413 digits
SHIFT=7 468750^1048576+1 Time: 3.94 ms/mul. Err: 1.64e-001 5946413 digits
SHIFT=8 468750^1048576+1 Time: 3.88 ms/mul. Err: 1.64e-001 5946413 digits
SHIFT=9 468750^1048576+1 Time: 4.13 ms/mul. Err: 1.72e-001 5946413 digits
SHIFT=10 468750^1048576+1 Time: 5.93 ms/mul. Err: 1.64e-001 5946413 digits

Command line: GeneferCUDA-boinc-windows.exe -b2 21

Generalized Fermat Number Bench 2
SHIFT=4 380742^2097152+1 Time: 55.3 ms/mul. Err: 3.63e-001 11703432 digits
SHIFT=5 380742^2097152+1 Time: 14.1 ms/mul. Err: 3.63e-001 11703432 digits
SHIFT=6 380742^2097152+1 Time: 8.88 ms/mul. Err: 3.63e-001 11703432 digits
SHIFT=7 380742^2097152+1 Time: 8.31 ms/mul. Err: 3.63e-001 11703432 digits
SHIFT=8 380742^2097152+1 Time: 8.09 ms/mul. Err: 3.63e-001 11703432 digits
SHIFT=9 380742^2097152+1 Time: 8.2 ms/mul. Err: 3.63e-001 11703432 digits
SHIFT=10 380742^2097152+1 Time: 9.66 ms/mul. Err: 3.63e-001 11703432 digits

Command line: GeneferCUDA-boinc-windows.exe -b2 22

Generalized Fermat Number Bench 2
SHIFT=4 309258^4194304+1 Time: 110 ms/mul. Err: 1.56e-001 23028076 digits
SHIFT=5 309258^4194304+1 Time: 27.7 ms/mul. Err: 1.56e-001 23028076 digits
SHIFT=6 309258^4194304+1 Time: 17.8 ms/mul. Err: 1.56e-001 23028076 digits
SHIFT=7 309258^4194304+1 Time: 16.6 ms/mul. Err: 1.56e-001 23028076 digits
SHIFT=8 309258^4194304+1 Time: 16.2 ms/mul. Err: 1.56e-001 23028076 digits
SHIFT=9 309258^4194304+1 Time: 15.9 ms/mul. Err: 1.56e-001 23028076 digits
SHIFT=10 309258^4194304+1 Time: 16 ms/mul. Err: 1.56e-001 23028076 digits

Holy crap :) those are some MAJOR differences in run times. Wish I hadn't gone to bed and read this first. I will have to test this out this evening if I can.

How soon with 1.05 be published?

It looks to me that part of the difference will be based on each gpu card and how it handles the blocks because in your case 6 seems to be the magic number not 8

You may now download 1.05 Beta 2. It uses the actual computation software for the benchmarks, so they should be a very accurate representation of how quickly the software will run real WUs.

Here's the benchmark results:

Command line: GeneferCUDA-boinc-windows.exe -b2 18

Generalized Fermat Number Bench 2
SHIFT=5 710492^262144+1 Time: 1.89 ms/mul. Err: 1.88e-001 1533952 digits
SHIFT=6 710492^262144+1 Time: 1.04 ms/mul. Err: 1.88e-001 1533952 digits
SHIFT=7 710492^262144+1 Time: 1.01 ms/mul. Err: 2.03e-001 1533952 digits
SHIFT=8 710492^262144+1 Time: 1.05 ms/mul. Err: 1.88e-001 1533952 digits
SHIFT=9 710492^262144+1 Time: 1.66 ms/mul. Err: 1.88e-001 1533952 digits
SHIFT=10 710492^262144+1 Time: 3.63 ms/mul. Err: 1.88e-001 1533952 digits

Command line: GeneferCUDA-boinc-windows.exe -b2 19

Generalized Fermat Number Bench 2
SHIFT=5 577098^524288+1 Time: 3.62 ms/mul. Err: 1.88e-001 3020555 digits
SHIFT=6 577098^524288+1 Time: 2.06 ms/mul. Err: 1.72e-001 3020555 digits
SHIFT=7 577098^524288+1 Time: 1.92 ms/mul. Err: 1.88e-001 3020555 digits
SHIFT=8 577098^524288+1 Time: 1.96 ms/mul. Err: 1.88e-001 3020555 digits
SHIFT=9 577098^524288+1 Time: 2.36 ms/mul. Err: 1.72e-001 3020555 digits
SHIFT=10 577098^524288+1 Time: 4.33 ms/mul. Err: 1.72e-001 3020555 digits

Command line: GeneferCUDA-boinc-windows.exe -b2 20

Generalized Fermat Number Bench 2
SHIFT=5 468750^1048576+1 Time: 7.03 ms/mul. Err: 1.64e-001 5946413 digits
SHIFT=6 468750^1048576+1 Time: 4.23 ms/mul. Err: 1.72e-001 5946413 digits
SHIFT=7 468750^1048576+1 Time: 3.91 ms/mul. Err: 1.56e-001 5946413 digits
SHIFT=8 468750^1048576+1 Time: 3.81 ms/mul. Err: 1.72e-001 5946413 digits
SHIFT=9 468750^1048576+1 Time: 4.01 ms/mul. Err: 1.64e-001 5946413 digits
SHIFT=10 468750^1048576+1 Time: 5.77 ms/mul. Err: 1.72e-001 5946413 digits

Command line: GeneferCUDA-boinc-windows.exe -b2 21

Generalized Fermat Number Bench 2
SHIFT=5 380742^2097152+1 Time: 14 ms/mul. Err: 1.64e-001 11703432 digits
SHIFT=6 380742^2097152+1 Time: 8.85 ms/mul. Err: 1.64e-001 11703432 digits
SHIFT=7 380742^2097152+1 Time: 8.26 ms/mul. Err: 1.64e-001 11703432 digits
SHIFT=8 380742^2097152+1 Time: 7.99 ms/mul. Err: 1.64e-001 11703432 digits
SHIFT=9 380742^2097152+1 Time: 8.03 ms/mul. Err: 1.72e-001 11703432 digits
SHIFT=10 380742^2097152+1 Time: 9.42 ms/mul. Err: 1.76e-001 11703432 digits

Command line: GeneferCUDA-boinc-windows.exe -b2 22

Generalized Fermat Number Bench 2
SHIFT=5 60000^4194304+1 Time: 28 ms/mul. Err: 6.35e-003 20041019 digits
SHIFT=6 60000^4194304+1 Time: 17.8 ms/mul. Err: 6.10e-003 20041019 digits
SHIFT=7 60000^4194304+1 Time: 16.6 ms/mul. Err: 5.86e-003 20041019 digits
SHIFT=8 60000^4194304+1 Time: 16.2 ms/mul. Err: 6.35e-003 20041019 digits
SHIFT=9 60000^4194304+1 Time: 16 ms/mul. Err: 5.86e-003 20041019 digits
SHIFT=10 60000^4194304+1 Time: 16.1 ms/mul. Err: 5.86e-003 20041019 digits

Please note that there is a bug in beta 2: it does not update Boinc's progress counter.

I'll release a beta 3 build in an hour or so once it's completed a WU and there's no other obvious errors. In the meantime, you can use beta 2 if you wish; it just won't update the progress meter in the Boinc manager.


____________
Please do not PM me with support questions. They will usually go unanswered. Ask on the forums instead. Thank you!

My lucky number is 75898^524288+1

Beta 3 can now be downloaded from here: http://www.asgoodasitgoetz.com/distribution/geneferCUDA-boinc.1.05beta3.7z

Same as beta 2 except that the boinc progress meter works.


____________
Please do not PM me with support questions. They will usually go unanswered. Ask on the forums instead. Thank you!

My lucky number is 75898^524288+1

Michael Goetz,
http://www.primegrid.com/result.php?resultid=339575564

I don't know what did you wanted hide, but the last row of log shows the whole number view:

568204^262144+1 is a probable composite. (RES=e62a18ec02671c3e) (1508509 digits) (err = 0.1270) (time = 1:19:48) 23:38:46

Command line: ./GeneferCUDA-boinc -b2 18

Generalized Fermat Number Bench 2
SHIFT=5 710492^262144+1 Time: 1.64 ms/mul. Err: 1.88e-01 1533952 digits CPU=75%
SHIFT=6 710492^262144+1 Time: 529 us/mul. Err: 1.88e-01 1533952 digits CPU=27%
SHIFT=7 710492^262144+1 Time: 255 us/mul. Err: 1.72e-01 1533952 digits CPU=14%
SHIFT=8 710492^262144+1 Time: 188 us/mul. Err: 1.88e-01 1533952 digits CPU=9%
SHIFT=9 710492^262144+1 Time: 185 us/mul. Err: 1.88e-01 1533952 digits CPU=6%
SHIFT=10 710492^262144+1 Time: 183 us/mul. Err: 1.72e-01 1533952 digits CPU=3%

Command line: ./GeneferCUDA-boinc -b2 19

Generalized Fermat Number Bench 2
SHIFT=5 577098^524288+1 Time: 3.46 ms/mul. Err: 1.80e-01 3020555 digits CPU=78%
SHIFT=6 577098^524288+1 Time: 886 us/mul. Err: 1.72e-01 3020555 digits CPU=23%
SHIFT=7 577098^524288+1 Time: 347 us/mul. Err: 1.72e-01 3020555 digits CPU=9%
SHIFT=8 577098^524288+1 Time: 200 us/mul. Err: 1.72e-01 3020555 digits CPU=6%
SHIFT=9 577098^524288+1 Time: 187 us/mul. Err: 1.88e-01 3020555 digits CPU=4%
SHIFT=10 577098^524288+1 Time: 184 us/mul. Err: 1.88e-01 3020555 digits CPU=2%

Command line: ./GeneferCUDA-boinc -b2 20

Generalized Fermat Number Bench 2
SHIFT=5 468750^1048576+1 Time: 8.11 ms/mul. Err: 1.72e-01 5946413 digits CPU=91%
SHIFT=6 468750^1048576+1 Time: 4.3 ms/mul. Err: 1.72e-01 5946413 digits CPU=53%
SHIFT=7 468750^1048576+1 Time: 531 us/mul. Err: 1.64e-01 5946413 digits CPU=7%
SHIFT=8 468750^1048576+1 Time: 259 us/mul. Err: 1.64e-01 5946413 digits CPU=3%
SHIFT=9 468750^1048576+1 Time: 184 us/mul. Err: 1.76e-01 5946413 digits CPU=2%
SHIFT=10 468750^1048576+1 Time: 187 us/mul. Err: 1.88e-01 5946413 digits CPU=2%

Command line: ./GeneferCUDA-boinc -b2 21

Generalized Fermat Number Bench 2
SHIFT=5 380742^2097152+1 Time: 17.8 ms/mul. Err: 1.64e-01 11703432 digits CPU=93%
SHIFT=6 380742^2097152+1 Time: 13 ms/mul. Err: 1.68e-01 11703432 digits CPU=78%
SHIFT=7 380742^2097152+1 Time: 1.46 ms/mul. Err: 1.64e-01 11703432 digits CPU=9%
SHIFT=8 380742^2097152+1 Time: 349 us/mul. Err: 1.66e-01 11703432 digits CPU=2%
SHIFT=9 380742^2097152+1 Time: 208 us/mul. Err: 1.56e-01 11703432 digits CPU=1%
SHIFT=10 380742^2097152+1 Time: 186 us/mul. Err: 1.58e-01 11703432 digits CPU=1%

Command line: ./GeneferCUDA-boinc -b2 22

Generalized Fermat Number Bench 2
SHIFT=5 60000^4194304+1 Time: 37.8 ms/mul. Err: 5.86e-03 20041019 digits CPU=100%
SHIFT=6 60000^4194304+1 Time: 31.8 ms/mul. Err: 5.00e-01 20041019 digits CPU=92%
SHIFT=7 60000^4194304+1 Time: 18 ms/mul. Err: 6.35e-03 20041019 digits CPU=52-54%
SHIFT=8 60000^4194304+1 Time: 574 us/mul. Err: 5.86e-03 20041019 digits CPU=2%
SHIFT=9 60000^4194304+1 Time: 292 us/mul. Err: 6.35e-03 20041019 digits CPU=1%
SHIFT=10 60000^4194304+1 Time: 218 us/mul. Err: 6.35e-03 20041019 digits CPU=1%

Ronald,

Something that both Shoichiro and myself have noticed is that when the test runs are too short (and 'too short' can be pretty long) the results can show really short execution times -- times that just don't make sense. I think your benchmarks are exhibiting that behavior.

In particular, there should absolutely be a significant increase in time per iteration as you increase N, and I don't see that in your results.

You might want to try increasing BENCHCOUNT and see if you get more rational results.

I have BENCHCOUNT set to 10000, and the benchmarks are quite annoyingly long -- but the results started getting whacky when I made it smaller. To be honest, I'm not really sure why the timing gets thrown off with shorter tests because it should be more than long enough, but it's not.
____________
Please do not PM me with support questions. They will usually go unanswered. Ask on the forums instead. Thank you!

My lucky number is 75898^524288+1

Perhaps i broke this in the source-code or the linux-patch for lowering the cpu-usage caused that.
A diff should give you an idea what i had to change.
I hope my PM with app and source came through...
____________
Best wishes. Knowledge is power. by jjwhalen

First error in a unit #339876464 after ~12ksec.
Shift 9 was to much...

____________
Best wishes. Knowledge is power. by jjwhalen

Ronald,

Don't use your -b2 benchmark results to select a propper shift value. While it's possible the 9 is the best value for you, it's a certainty that the benchmark results you got are meaningless.

Until we figure out what's wrong with the benchmarks they should not be used to decide what shift value is best.

There's two easy ways to determine that the benchmarks are not working:

1) The iteration times are simply too fast. Unless your hardware is really fast, the times should all be in milliseconds (ms), not microseconds (us). For the n=18 benchmark (which corresponds to our WUs), I was getting times around 1 millisecond. Since the test is executed 10,000 times, that part of the test should take about 10 seconds. If the test takes 10 seconds, but the computer is saying it did 10,000 iterations in 186 microseconds, the test should have finished in 2 seconds.

2) As you increase n, the length of each iteration increases almost by a factor of 2. So your test results at n=19 should be significantly higher than at 18, at 20 they should be significantly higher than at 19, and so on. You were seeing identical numbers at all values of n.

I have no clue what's wrong there. Shoichiro has observed the same behavior --- look at his posts on the Mersenne forum. I don't understand what caused it then, and I don't understand what caused it now. Maybe another set of eyeballs will help.

I guess the first place to start is to grab a stopwatch and see how long those tests actually take.

Your tests are saying it's taking a bit under 200 microseconds, so that should take 2 seconds to run. Is it taking 2 seconds? Or is it taking 10 to 20 seconds for each line? (My 460 takes 10 seconds per line, your 450 should be slower.) If it's taking 10 or more seconds, the clock readings are wrong. If it's taking 2 seconds, something is very wrong. Or at least very weird.

____________
Please do not PM me with support questions. They will usually go unanswered. Ask on the forums instead. Thank you!

My lucky number is 75898^524288+1

Your tests show that, on your computer, block sizes of 7, 7, 8, 8, and 9 are the fastest at n values of 18 through 22, respectively. Those are the same as I got on my card.

Two data points are better than 1!

If enough people show similar results I may change the program to default to those values.

The default values for those n are currently: 8, 8, 8, 9, and 9. (I have previously said that the defaults for those values were, 8, 8, 9, 9, and 10, but that was a mistake.) If the 7, 7, 8, 8, 9 numbers hold up for a wide range of GPUs then the current default values aren't optimal and should be changed. I'll need a lot more data, however.
____________
Please do not PM me with support questions. They will usually go unanswered. Ask on the forums instead. Thank you!

My lucky number is 75898^524288+1

In the moment i calculate an unit with shift=6 and see 27% cpu-usage via 'top'. For shift=7 i have only the benchmark value of 14% cpu load via 'top' but the computation time was only ~10min shorter.
A 262144-WU with the default value 8 causes 9% cpu load on one core and needed ~10ksec (~2hrs50) on my slower GTS450 green/eco-version.
From my point of view should the defaults values stay where they are. Max 10% cpu usage while calculating an unit on the gpu should be tolerable for all.
____________
Best wishes. Knowledge is power. by jjwhalen

In the moment i calculate an unit with shift=6 and see 27% cpu-usage via 'top'. For shift=7 i have only the benchmark value of 14% cpu load via 'top' but the computation time was only ~10min shorter.
A 262144-WU with the default value 8 causes 9% cpu load on one core and needed ~10ksec (~2hrs50) on my slower GTS450 green/eco-version.
From my point of view should the defaults values stay where they are. Max 10% cpu usage while calculating an unit on the gpu should be tolerable for all.

That's comparing the output of the measurement tools: top on Linux, task manager on Windows. One or both might be inaccurate due to the high frequency at which a GPU app's CPU thread blocks and unblocks.

I'm actually very concerned about our ability to measure CPU utilization on this kind of app. I may need to write my own measurement tool for this.

That's comparing the output of the measurement tools: top on Linux, task manager on Windows. One or both might be inaccurate due to the high frequency at which a GPU app's CPU thread blocks and unblocks.

I'm actually very concerned about our ability to measure CPU utilization on this kind of app. I may need to write my own measurement tool for this.

Both tools are inaccurate because each cpu changed their clock rates more than 10.000 times per second.
Intel released a tool to read out all SB performance data directly from hidden registers.
AMDs Bulldozer makes this much easier via LWP (Lightweight Profiling). In the past you need kernel-driver and complicated configurations, with LWP you can read the latency-time, cache-miss, fpu-operations etc directly in user-mode via cpu-commands like 'lwpins', 'lwpval', 'bextr' etc.

But do you really need this accuracy?
Sysinternals Process-Explorer has a min-setting of 0.5sec and neither Windows nor Linux are known to be realtime-OS (special libraries on the Win-platform or a kernel with realtime-extensions are another story). This limits the ability for measuring and in the most cases you need only an approximate or average value.

either Nvidia's drivers or libraries are better under Windows, or the tools aren't measuring CPU consumption equally

In the moment i calculate an unit with shift=6 and see 27% cpu-usage via 'top'. For shift=7 i have only the benchmark value of 14% cpu load via 'top' but the computation time was only ~10min shorter.
A 262144-WU with the default value 8 causes 9% cpu load on one core and needed ~10ksec (~2hrs50) on my slower GTS450 green/eco-version.
From my point of view should the defaults values stay where they are. Max 10% cpu usage while calculating an unit on the gpu should be tolerable for all.

On the other side could it be that newer sdk's have a solution for the problems on a GTX550 and i want to make some experiments with the new LLVM-based CUDA compiler...

IIRC trying the different toolkits and SDKs was the very first thing I tried with regards to the 550 problem. The behavior was unchanged with 3.2, 4.0, or 4.1.

Switched to Windows to run the benchmarks before fully testing on Linux.

GTX 480, 1536 MB
Core 701 MHz
Memory 924 MHz
Shader 1401 MHz
Driver 280.26
System: i7 875K, 8 GB, Win 7 Ultimate 64-bit SP1

Edit: app v1.05beta3 :)

Command line: GeneferCUDA-boinc-windows.exe -b2 18

Generalized Fermat Number Bench 2
SHIFT=5 710492^262144+1 Time: 1 ms/mul. Err: 1.88e-001 1533952 digits
SHIFT=6 710492^262144+1 Time: 616 us/mul. Err: 1.88e-001 1533952 digits
SHIFT=7 710492^262144+1 Time: 568 us/mul. Err: 2.03e-001 1533952 digits
SHIFT=8 710492^262144+1 Time: 630 us/mul. Err: 1.88e-001 1533952 digits
SHIFT=9 710492^262144+1 Time: 981 us/mul. Err: 1.88e-001 1533952 digits
SHIFT=10 710492^262144+1 Time: 1.99 ms/mul. Err: 1.88e-001 1533952 digits

Command line: GeneferCUDA-boinc-windows.exe -b2 19

Generalized Fermat Number Bench 2
SHIFT=5 577098^524288+1 Time: 1.88 ms/mul. Err: 1.88e-001 3020555 digits
SHIFT=6 577098^524288+1 Time: 1.17 ms/mul. Err: 1.72e-001 3020555 digits
SHIFT=7 577098^524288+1 Time: 1.05 ms/mul. Err: 1.88e-001 3020555 digits
SHIFT=8 577098^524288+1 Time: 1.05 ms/mul. Err: 1.88e-001 3020555 digits
SHIFT=9 577098^524288+1 Time: 1.33 ms/mul. Err: 1.72e-001 3020555 digits
SHIFT=10 577098^524288+1 Time: 2.34 ms/mul. Err: 1.72e-001 3020555 digits

Command line: GeneferCUDA-boinc-windows.exe -b2 20

Generalized Fermat Number Bench 2
SHIFT=5 468750^1048576+1 Time: 3.7 ms/mul. Err: 1.64e-001 5946413 digits
SHIFT=6 468750^1048576+1 Time: 2.27 ms/mul. Err: 1.72e-001 5946413 digits
SHIFT=7 468750^1048576+1 Time: 1.98 ms/mul. Err: 1.56e-001 5946413 digits
SHIFT=8 468750^1048576+1 Time: 1.92 ms/mul. Err: 1.72e-001 5946413 digits
SHIFT=9 468750^1048576+1 Time: 1.98 ms/mul. Err: 1.64e-001 5946413 digits
SHIFT=10 468750^1048576+1 Time: 2.97 ms/mul. Err: 1.72e-001 5946413 digits

Command line: GeneferCUDA-boinc-windows.exe -b2 21

Generalized Fermat Number Bench 2
SHIFT=5 380742^2097152+1 Time: 7.19 ms/mul. Err: 1.64e-001 11703432 digits
SHIFT=6 380742^2097152+1 Time: 4.56 ms/mul. Err: 1.64e-001 11703432 digits
SHIFT=7 380742^2097152+1 Time: 3.87 ms/mul. Err: 1.64e-001 11703432 digits
SHIFT=8 380742^2097152+1 Time: 3.7 ms/mul. Err: 1.64e-001 11703432 digits
SHIFT=9 380742^2097152+1 Time: 3.69 ms/mul. Err: 1.72e-001 11703432 digits
SHIFT=10 380742^2097152+1 Time: 4.31 ms/mul. Err: 1.76e-001 11703432 digits

Command line: GeneferCUDA-boinc-windows.exe -b2 22

Generalized Fermat Number Bench 2
SHIFT=5 60000^4194304+1 Time: 14.6 ms/mul. Err: 6.35e-003 20041019 digits
SHIFT=6 60000^4194304+1 Time: 9.36 ms/mul. Err: 6.10e-003 20041019 digits
SHIFT=7 60000^4194304+1 Time: 8.22 ms/mul. Err: 5.86e-003 20041019 digits
SHIFT=8 60000^4194304+1 Time: 7.68 ms/mul. Err: 6.35e-003 20041019 digits
SHIFT=9 60000^4194304+1 Time: 7.53 ms/mul. Err: 5.86e-003 20041019 digits
SHIFT=10 60000^4194304+1 Time: 7.63 ms/mul. Err: 5.86e-003 20041019 digits

So for my system 7, 7, 8, 8, 9 would be ok and near optimal.

The app used a full CPU core with shift=5 across all n, and roughly 30 % of a core at shift=6, n=18. Otherwise, the task manager didn't show CPU usage other than at the shift changes.

No screen lag noted.
____________

GT 440, 1536 MB, OEM version with 144 shaders
Core 719 MHz
Memory 800 MHz
Shader 1439 MHz
Driver 285.62
System: i7 920, 6 GB, Win Vista Home 64-bit SP2

Command line: GeneferCUDA-boinc-windows.exe -b2 18

Generalized Fermat Number Bench 2
SHIFT=5 710492^262144+1 Time: 2.31 ms/mul. Err: 1.88e-001 1533952 digits
SHIFT=6 710492^262144+1 Time: 2.11 ms/mul. Err: 1.88e-001 1533952 digits
SHIFT=7 710492^262144+1 Time: 2.04 ms/mul. Err: 2.03e-001 1533952 digits
SHIFT=8 710492^262144+1 Time: 2.18 ms/mul. Err: 1.88e-001 1533952 digits
SHIFT=9 710492^262144+1 Time: 3.13 ms/mul. Err: 1.88e-001 1533952 digits
SHIFT=10 710492^262144+1 Time: 6.71 ms/mul. Err: 1.88e-001 1533952 digits

Command line: GeneferCUDA-boinc-windows.exe -b2 19

Generalized Fermat Number Bench 2
SHIFT=5 577098^524288+1 Time: 6.65 ms/mul. Err: 1.88e-001 3020555 digits
SHIFT=6 577098^524288+1 Time: 4.42 ms/mul. Err: 1.72e-001 3020555 digits
SHIFT=7 577098^524288+1 Time: 4.47 ms/mul. Err: 1.88e-001 3020555 digits
SHIFT=8 577098^524288+1 Time: 4.51 ms/mul. Err: 1.88e-001 3020555 digits
SHIFT=9 577098^524288+1 Time: 5.15 ms/mul. Err: 1.72e-001 3020555 digits
SHIFT=10 577098^524288+1 Time: 8.49 ms/mul. Err: 1.72e-001 3020555
digits

Command line: GeneferCUDA-boinc-windows.exe -b2 20

Generalized Fermat Number Bench 2
SHIFT=5 468750^1048576+1 Time: 13.2 ms/mul. Err: 1.64e-001 5946413 digits
SHIFT=6 468750^1048576+1 Time: 8.91 ms/mul. Err: 1.72e-001 5946413 digits
SHIFT=7 468750^1048576+1 Time: 8.67 ms/mul. Err: 1.56e-001 5946413 digits
SHIFT=8 468750^1048576+1 Time: 8.78 ms/mul. Err: 1.72e-001 5946413 digits
SHIFT=9 468750^1048576+1 Time: 8.72 ms/mul. Err: 1.64e-001 5946413 digits
SHIFT=10 468750^1048576+1 Time: 12.3 ms/mul. Err: 1.72e-001 5946413 digits

Command line: GeneferCUDA-boinc-windows.exe -b2 21

Generalized Fermat Number Bench 2
SHIFT=5 380742^2097152+1 Time: 24.2 ms/mul. Err: 1.64e-001 11703432 digits
SHIFT=6 380742^2097152+1 Time: 18.9 ms/mul. Err: 1.64e-001 11703432 digits
SHIFT=7 380742^2097152+1 Time: 18.4 ms/mul. Err: 1.64e-001 11703432 digits
SHIFT=8 380742^2097152+1 Time: 18.5 ms/mul. Err: 1.64e-001 11703432 digits
SHIFT=9 380742^2097152+1 Time: 18.4 ms/mul. Err: 1.72e-001 11703432 digits
SHIFT=10 380742^2097152+1 Time: 20.4 ms/mul. Err: 1.76e-001 11703432 digits

Command line: GeneferCUDA-boinc-windows.exe -b2 22

Generalized Fermat Number Bench 2
SHIFT=5 60000^4194304+1 Time: 49.6 ms/mul. Err: 6.35e-003 20041019 digits
SHIFT=6 60000^4194304+1 Time: 37.7 ms/mul. Err: 6.10e-003 20041019 digits
SHIFT=7 60000^4194304+1 Time: 36.6 ms/mul. Err: 5.86e-003 20041019 digits
SHIFT=8 60000^4194304+1 Time: 36.7 ms/mul. Err: 6.35e-003 20041019 digits
SHIFT=9 60000^4194304+1 Time: 36.3 ms/mul. Err: 5.86e-003 20041019 digits
SHIFT=10 60000^4194304+1 Time: 36.6 ms/mul. Err: 5.86e-003 20041019
digits

As Michael noted earlier, there's something wrong with benchmarking with the Linux app (1.05). I'm getting similar results to yours and ronald's and they're clearly faulty. The time for each respective shift should significantly increase with the n, and it doesn't for the higher shift values. The times are also way too fast to be realistic.

If the app is running fine in BOINC, there shouldn't be any problem with actual wu's.

BOINC wu's are processing fine here, and I'll compile a test report and post later today.
____________

I've tried 6,7,8 and 9 and it looks like 7 may be the best block size for my card. Question, will 32bit vs 64 bit windows make a difference in runtime?

Does this still hold true for different shift values (e.g. ones that utilize more CPU)?
____________

Does this still hold true for different shift values (e.g. ones that utilize more CPU)?

cufftSafeCall(cufftExecZ2Z(plan,(cufftDoubleComplex *)g_z,(cufftDoubleComplex *)g_z, CUFFT_FORWARD));
mul_kernel<<< n/128,128 >>> ((double2*)g_z);
cufftSafeCall(cufftExecZ2Z(plan,(cufftDoubleComplex *)g_z,(cufftDoubleComplex *)g_z, CUFFT_INVERSE));
bt = Na[i / (8 * sizeof(UInt32))] >> (i % (8 * sizeof(UInt32))) & 1;
for(j=0;j<n1;j+=(STRIDE*STRIDE*2))
....transpose<<< grid, threads >>>((double *)&g_zz[j],(double *)&g_z[j],(int) STRIDE*2,(int) STRIDE*2);
FFTnextStepGFN_kernel<<< n1/STRIDE/ithreads,ithreads >>>((double *)g_zz,(double *)g_e1,g_f1,g_f2,base,invBase,t,n1,g_maxErr,tt,SHIFT);
FFTnextStepGFN_kernel2<<< n1/STRIDE/ithreads,ithreads >>>((double *)g_zz,(double *)g_e1,g_f1,g_f2,base,invBase,t,n1,g_maxErr,SHIFT);
for(j=0;j<n1;j+=(STRIDE*STRIDE*2))
....transpose<<< grid, threads >>>((double *)&g_z[j],(double *)&g_zz[j],(int) STRIDE*2,(int) STRIDE*2);

GTX 580/i5-2500/Win 7 x64 default setting.

Merged app_info with AVX, running 3 PPS LLR AVX task along GPU GFN, watching progress via VNC. GPU time 3085 secs, CPU time 270 secs.

Second WU time estimation after 20% is almost 4 hours, DCF 4.5.
Will see how it settles down along PPS LLR.
(I know I can set DCF to 1 but it will eventually adjust anyway).

Next WU it have SHIFT=7 manually, I might try to run 4 LLRs as well.

So far - good job!
____________
My stats
Badge score: 1*1 + 5*2 + 8*13 + 9*2 + 12*3 = 169

By the way what will be maxErr allowed at b22?

IMPORTANT UPDATE

As of GeneferCUDA for Windows V1.06, the default block size has been changed to the following:

For N <= 65536 the block size is 6
(This will use a lot of CPU, even a full core, but the speed increase is very significant. Neither Boinc nor PRPNet is currently using GeneferCUDA with N values this low, however.)

For 131072 <= N <= 1048576 the block size is 7
(This makes this version especially useful for PRPNet as well as Boinc.)

For N >= 2097152 the block size is 8

These changes should generally produce speed improvements on most systems. You are encouraged, however, to run the appropriate -b2 test to see which is best for your hardware.

This does not apply to the Linux distribution of GeneferCUDA. The Linux build may need different tuning than the Windows build, so Ronald is in a better position to address the best values for Linux.
____________
Please do not PM me with support questions. They will usually go unanswered. Ask on the forums instead. Thank you!

My lucky number is 75898^524288+1

These are the benchmarks from my old screwed up OS. The lag is much better at SHIFT=7 and is very acceptable. It virtually disappears except minor lags here and there on SHIFT=6. At SHIFT=5 the lag begins to return though. And CPU usage is strangely low. At SHIFT=7 it's 2-3%, at SHIFT=6 it's 5-8% and at SHIFT=5 it's at 20-24%. Oh, and at the default SHIFT=8 there is a slight improvement there now even but still beyond acceptable.

Generalized Fermat Number Bench 2 -b2 18
SHIFT=5 710492^262144+1 Time: 1.04 ms/mul. Err: 1.88e-001 1533952 digits
SHIFT=6 710492^262144+1 Time: 804 us/mul. Err: 1.88e-001 1533952 digits
SHIFT=7 710492^262144+1 Time: 771 us/mul. Err: 2.03e-001 1533952 digits
SHIFT=8 710492^262144+1 Time: 798 us/mul. Err: 1.88e-001 1533952 digits
SHIFT=9 710492^262144+1 Time: 1.29 ms/mul. Err: 1.88e-001 1533952 digits
SHIFT=10 710492^262144+1 Time: 2.84 ms/mul. Err: 1.88e-001 1533952 digits

Generalized Fermat Number Bench 2 -b2 19
SHIFT=5 577098^524288+1 Time: 2.07 ms/mul. Err: 1.88e-001 3020555 digits
SHIFT=6 577098^524288+1 Time: 1.63 ms/mul. Err: 1.72e-001 3020555 digits
SHIFT=7 577098^524288+1 Time: 1.5 ms/mul. Err: 1.88e-001 3020555 digits
SHIFT=8 577098^524288+1 Time: 1.51 ms/mul. Err: 1.88e-001 3020555 digits
SHIFT=9 577098^524288+1 Time: 1.8 ms/mul. Err: 1.72e-001 3020555 digits
SHIFT=10 577098^524288+1 Time: 3.31 ms/mul. Err: 1.72e-001 3020555 digits

Generalized Fermat Number Bench 2 -b2 20
SHIFT=5 468750^1048576+1 Time: 4.18 ms/mul. Err: 1.64e-001 5946413 digits
SHIFT=6 468750^1048576+1 Time: 3.31 ms/mul. Err: 1.72e-001 5946413 digits
SHIFT=7 468750^1048576+1 Time: 3.06 ms/mul. Err: 1.56e-001 5946413 digits
SHIFT=8 468750^1048576+1 Time: 2.95 ms/mul. Err: 1.72e-001 5946413 digits
SHIFT=9 468750^1048576+1 Time: 3 ms/mul. Err: 1.64e-001 5946413 digits
SHIFT=10 468750^1048576+1 Time: 4.39 ms/mul. Err: 1.72e-001 5946413 digits

Generalized Fermat Number Bench 2 -b2 21
SHIFT=5 380742^2097152+1 Time: 8.56 ms/mul. Err: 1.64e-001 11703432 digits
SHIFT=6 380742^2097152+1 Time: 6.86 ms/mul. Err: 1.64e-001 11703432 digits
SHIFT=7 380742^2097152+1 Time: 6.51 ms/mul. Err: 1.64e-001 11703432 digits
SHIFT=8 380742^2097152+1 Time: 6.23 ms/mul. Err: 1.64e-001 11703432 digits
SHIFT=9 380742^2097152+1 Time: 6.01 ms/mul. Err: 1.72e-001 11703432 digits
SHIFT=10 380742^2097152+1 Time: 7.01 ms/mul. Err: 1.76e-001 11703432 digits

Generalized Fermat Number Bench 2 -b2 22
SHIFT=5 60000^4194304+1 Time: 17.3 ms/mul. Err: 6.35e-003 20041019 digits
SHIFT=6 60000^4194304+1 Time: 13.8 ms/mul. Err: 6.10e-003 20041019 digits
SHIFT=7 60000^4194304+1 Time: 13 ms/mul. Err: 5.86e-003 20041019 digits
SHIFT=8 60000^4194304+1 Time: 12.6 ms/mul. Err: 6.35e-003 20041019 digits
SHIFT=9 60000^4194304+1 Time: 12.1 ms/mul. Err: 5.86e-003 20041019 digits

Strange that at b2 22 it quit after SHIFT=9 so no SHIFT=10 there.

NeoMetal*
____________
Largest Primes to Date:
As Double Checker: SR5 109208*5^1816285+1 Dgts-1,269,534
As Initial Finder: SR5 243944*5^1258576-1 Dgts-879,713

What is the current N and when will it change?

boinc@vmware2k-3:~/Cuda/test/Genefer$ time ./GeneferCUDA-boinc -b
GeneferCUDA-boinc 1.06 (CUDA3.2) based on GeneferCUDA 1.049 and Genefer 2.2.1
Copyright (C) 2001-2003, Yves Gallot (v1.3)
Copyright (C) 2009-2011, Mark Rodenkirch, David Underbakke (v2.2.1)
Copyright (C) 2010-2012, Shoichiro Yamada (CUDA)
Portions of this software written by Michael Goetz 2011-2012 (BOINC)
A program for finding large probable generalized Fermat primes.

./GeneferCUDA-boinc -b

Generalized Fermat Number Bench
2009574^8192+1 Time: 155 us/mul. Err: 1.88e-01 51636 digits
1632282^16384+1 Time: 144 us/mul. Err: 1.72e-01 101791 digits
1325824^32768+1 Time: 172 us/mul. Err: 1.88e-01 200622 digits
1076904^65536+1 Time: 215 us/mul. Err: 1.72e-01 395325 digits
874718^131072+1 Time: 310 us/mul. Err: 1.88e-01 778813 digits
710492^262144+1 Time: 255 us/mul. Err: 1.72e-01 1533952 digits
577098^524288+1 Time: 346 us/mul. Err: 1.72e-01 3020555 digits
468750^1048576+1 Time: 525 us/mul. Err: 1.64e-01 5946413 digits
380742^2097152+1 Time: 1.46 ms/mul. Err: 1.64e-01 11703432 digits
309258^4194304+1 Time: 567 us/mul. Err: 1.56e-01 23028076 digits
100^8388608+1 Time: 8.39 ms/mul. Err: 3.81e-05 16777217 digits

real 23m3.409s
user 1m30.650s
sys 0m44.859s

boinc@vmware2k-3:~/Cuda/test/Genefer$ time ./GeneferCUDA-boinc -b2 18
GeneferCUDA-boinc 1.06 (CUDA3.2) based on GeneferCUDA 1.049 and Genefer 2.2.1
Copyright (C) 2001-2003, Yves Gallot (v1.3)
Copyright (C) 2009-2011, Mark Rodenkirch, David Underbakke (v2.2.1)
Copyright (C) 2010-2012, Shoichiro Yamada (CUDA)
Portions of this software written by Michael Goetz 2011-2012 (BOINC)
A program for finding large probable generalized Fermat primes.

./GeneferCUDA-boinc -b2 18

Generalized Fermat Number Bench 2
SHIFT=5 710492^262144+1 Time: 1.64 ms/mul. Err: 1.88e-01 1533952 digits CPU=75
SHIFT=6 710492^262144+1 Time: 531 us/mul. Err: 1.88e-01 1533952 digits CPU=28
SHIFT=7 710492^262144+1 Time: 255 us/mul. Err: 1.72e-01 1533952 digits CPU=14
SHIFT=8 710492^262144+1 Time: 183 us/mul. Err: 1.88e-01 1533952 digits CPU=10
SHIFT=9 710492^262144+1 Time: 189 us/mul. Err: 1.88e-01 1533952 digits CPU=6
SHIFT=10 710492^262144+1 Time: 186 us/mul. Err: 1.72e-01 1533952 digits CPU=3

real 3m14.141s
user 0m30.826s
sys 0m0.512s

boinc@vmware2k-3:~/Cuda/test/Genefer$ time ./GeneferCUDA-boinc -b2 19
GeneferCUDA-boinc 1.06 (CUDA3.2) based on GeneferCUDA 1.049 and Genefer 2.2.1
Copyright (C) 2001-2003, Yves Gallot (v1.3)
Copyright (C) 2009-2011, Mark Rodenkirch, David Underbakke (v2.2.1)
Copyright (C) 2010-2012, Shoichiro Yamada (CUDA)
Portions of this software written by Michael Goetz 2011-2012 (BOINC)
A program for finding large probable generalized Fermat primes.

./GeneferCUDA-boinc -b2 19

Generalized Fermat Number Bench 2
SHIFT=5 577098^524288+1 Time: 3.46 ms/mul. Err: 1.80e-01 3020555 digits CPU=77-79
SHIFT=6 577098^524288+1 Time: 895 us/mul. Err: 1.72e-01 3020555 digits CPU=22
SHIFT=7 577098^524288+1 Time: 349 us/mul. Err: 1.72e-01 3020555 digits CPU=9
SHIFT=8 577098^524288+1 Time: 210 us/mul. Err: 1.72e-01 3020555 digits CPU=6
SHIFT=9 577098^524288+1 Time: 194 us/mul. Err: 1.88e-01 3020555 digits CPU=4
SHIFT=10 577098^524288+1 Time: 191 us/mul. Err: 1.88e-01 3020555 digits CPU=2

real 5m9.052s
user 0m52.947s
sys 0m2.828s

boinc@vmware2k-3:~/Cuda/test/Genefer$ time ./GeneferCUDA-boinc -b2 20
GeneferCUDA-boinc 1.06 (CUDA3.2) based on GeneferCUDA 1.049 and Genefer 2.2.1
Copyright (C) 2001-2003, Yves Gallot (v1.3)
Copyright (C) 2009-2011, Mark Rodenkirch, David Underbakke (v2.2.1)
Copyright (C) 2010-2012, Shoichiro Yamada (CUDA)
Portions of this software written by Michael Goetz 2011-2012 (BOINC)
A program for finding large probable generalized Fermat primes.

./GeneferCUDA-boinc -b2 20

Generalized Fermat Number Bench 2
SHIFT=5 468750^1048576+1 Time: 8.12 ms/mul. Err: 1.72e-01 5946413 digits CPU=91
SHIFT=6 468750^1048576+1 Time: 4.3 ms/mul. Err: 1.72e-01 5946413 digits CPU=52-54
SHIFT=7 468750^1048576+1 Time: 530 us/mul. Err: 1.64e-01 5946413 digits CPU=7
SHIFT=8 468750^1048576+1 Time: 257 us/mul. Err: 1.64e-01 5946413 digits CPU=3
SHIFT=9 468750^1048576+1 Time: 188 us/mul. Err: 1.76e-01 5946413 digits CPU=2
SHIFT=10 468750^1048576+1 Time: 187 us/mul. Err: 1.88e-01 5946413 digits CPU=2

real 8m57.471s
user 1m54.707s
sys 0m26.590s

boinc@vmware2k-3:~/Cuda/test/Genefer$ time ./GeneferCUDA-boinc -b2 21
GeneferCUDA-boinc 1.06 (CUDA3.2) based on GeneferCUDA 1.049 and Genefer 2.2.1
Copyright (C) 2001-2003, Yves Gallot (v1.3)
Copyright (C) 2009-2011, Mark Rodenkirch, David Underbakke (v2.2.1)
Copyright (C) 2010-2012, Shoichiro Yamada (CUDA)
Portions of this software written by Michael Goetz 2011-2012 (BOINC)
A program for finding large probable generalized Fermat primes.

./GeneferCUDA-boinc -b2 21

Generalized Fermat Number Bench 2
SHIFT=5 380742^2097152+1 Time: 17.9 ms/mul. Err: 1.64e-01 11703432 digits CPU=98
SHIFT=6 380742^2097152+1 Time: 13.1 ms/mul. Err: 1.68e-01 11703432 digits CPU=78
SHIFT=7 380742^2097152+1 Time: 1.46 ms/mul. Err: 1.64e-01 11703432 digits CPU=9
SHIFT=8 380742^2097152+1 Time: 343 us/mul. Err: 1.66e-01 11703432 digits CPU=3
SHIFT=9 380742^2097152+1 Time: 205 us/mul. Err: 1.56e-01 11703432 digits CPU=2
SHIFT=10 380742^2097152+1 Time: 188 us/mul. Err: 1.58e-01 11703432 digits CPU=1

real 17m28.288s
user 4m10.508s
sys 1m31.246s

boinc@vmware2k-3:~/Cuda/test/Genefer$ time ./GeneferCUDA-boinc -b2 22
GeneferCUDA-boinc 1.06 (CUDA3.2) based on GeneferCUDA 1.049 and Genefer 2.2.1
Copyright (C) 2001-2003, Yves Gallot (v1.3)
Copyright (C) 2009-2011, Mark Rodenkirch, David Underbakke (v2.2.1)
Copyright (C) 2010-2012, Shoichiro Yamada (CUDA)
Portions of this software written by Michael Goetz 2011-2012 (BOINC)
A program for finding large probable generalized Fermat primes.

./GeneferCUDA-boinc -b2 22

Generalized Fermat Number Bench 2
SHIFT=5 309258^4194304+1 Time: 37.8 ms/mul. Err: 1.72e-01 23028076 digits CPU=100
SHIFT=6 309258^4194304+1 Time: 31.8 ms/mul. Err: 1.72e-01 23028076 digits CPU=90-92
SHIFT=7 309258^4194304+1 Time: 18 ms/mul. Err: 1.56e-01 23028076 digits CPU=51-54
SHIFT=8 309258^4194304+1 Time: 574 us/mul. Err: 1.56e-01 23028076 digits CPU=9
SHIFT=9 309258^4194304+1 Time: 294 us/mul. Err: 1.72e-01 23028076 digits CPU=1
SHIFT=10 309258^4194304+1 Time: 220 us/mul. Err: 1.72e-01 23028076 digits CPU=1

real 35m10.920s
user 10m1.898s
sys 5m7.015s

As I have been discussing with Ronald privately, you should ignore the benchmark results under Linux. We haven't worked the kinks out yet and the numbers you're seeing are useless. They are, plain and simple, completely wrong, unless, somehow, you've found a way to overclock your GPU to around 20 GHz or so without the chips melting into a molten pile of glass, your power supply exploding in flames, and the master circuit breaker in your house tripping. The benchmarks are reporting numbers that are approximately ten times faster than these GPUs are capable of.

The benchmark problem is not unique to the Linux version -- both Shoichiro and myself have seen this exact problem previously. Until it's solved, however, the benchmarks in the Linux version are, unfortunately, meaningless. Any pattern you see in the results is merely a coincidence.

For the time being, if you want to know what shift values are best on your system, grab a stopwatch and run GeneferCUDA from the command line computing actual numbers. Time how long it takes to do a set number of iterations at each block setting.

Chances are the defaults in the program are the best settings.

boinc@vmware2k-3:~/Cuda/test/Genefer$ time ./GeneferCUDA-boinc -b2 20
GeneferCUDA-boinc 1.06 (CUDA3.2) based on GeneferCUDA 1.049 and Genefer 2.2.1
Copyright (C) 2001-2003, Yves Gallot (v1.3)
Copyright (C) 2009-2011, Mark Rodenkirch, David Underbakke (v2.2.1)
Copyright (C) 2010-2012, Shoichiro Yamada (CUDA)
Portions of this software written by Michael Goetz 2011-2012 (BOINC)
A program for finding large probable generalized Fermat primes.

./GeneferCUDA-boinc -b2 20

Generalized Fermat Number Bench 2
SHIFT=5 468750^1048576+1 Time: 8.12 ms/mul. Err: 1.72e-01 5946413 digits CPU=91
SHIFT=6 468750^1048576+1 Time: 4.3 ms/mul. Err: 1.72e-01 5946413 digits CPU=52-54
SHIFT=7 468750^1048576+1 Time: 530 us/mul. Err: 1.64e-01 5946413 digits CPU=7
SHIFT=8 468750^1048576+1 Time: 257 us/mul. Err: 1.64e-01 5946413 digits CPU=3
SHIFT=9 468750^1048576+1 Time: 188 us/mul. Err: 1.76e-01 5946413 digits CPU=2
SHIFT=10 468750^1048576+1 Time: 187 us/mul. Err: 1.88e-01 5946413 digits CPU=2

real 8m57.471s
user 1m54.707s
sys 0m26.590s

If a higher shift value is not twice as fast as the lower value then we have reached an optimal value.

By this logic the shift value for b2=20 should be 8 because 257 is less than a half of 530 and so is more than twice as fast as shift value 7.
And this is consistent with the values Michael found for Windows.

Rainer

GT430 stock - 16,152.05 secs / 15.44 secs CPU
Block size 7 - GPU temp 62 degrees

Neo

Generally, I don't think there is a need to change it.

Below in this threat you will find some real numbers from testing.
You can run some benchmarks on your configuration and then set manually if it makes any difference.

____________
My stats
Badge score: 1*1 + 5*2 + 8*13 + 9*2 + 12*3 = 169

I have run the world record wu's on my GTX590 with the block size set to zero.
Run times were about 84 hours....
So how important is the block size? Do I need to change it?

Hello!
I'm preparing for upcoming GPU chelly.
I've installed new 301.xx Windows x86 NVidia drivers and I have terrible screen lags. Also there is a major increase of computation time. 3-4 times more than with 285.xx drivers.
I use default settings.
My GPUs are a pair of GTX 460 under W7 x86.
Need some advice!

NVIDIA GeForce GTX 660 Ti (2048MB) driver: 30697

Microsoft Windows 8
x64 Edition, (06.02.9200.00)

my graphic card made problems wi8th the rhigt setting.

this is overclocked from factory

Settings : 0, 7,8, is wrong and

crash

what to do ?

I believe the current "stock" app self-benchmarks when it starts a task, so there's no need to ever change the preferences page block size setting from 0. The app will pick the best block size for your box. The amount of time it takes to run the benchmarks is trivial compared to the amount of time the work unit itself will take, so that's not a concern.

The above assumes you're not running a different version with app_info.xml.

--Gary