Thread: rogue's sieves
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Old 2017-07-30, 21:54   #4
rogue's Avatar
Apr 2003
Between here and the

665210 Posts

Originally Posted by J F View Post
Yay, thanks a lot!
Runs out of the box and produces the same results as pixsieve.
6-year-old HD7950 (Tahiti) @stock 850MHz is ~5x faster than one
6600K core @3.9GHz. I will play around to see if there is a bit
more possible with different block sizes etc.
Minor confusion: pixsieveCL states 'OpenCL 2.0 AMD-APP (2442.0)'.
The software framework on my machine might be 2.0-capable, but
the card hardware is only 1.2.

Some questions:
1. Old pixsieve had options
-s --stringfile=s File containing a decimal representation of any number
-S --searchstring=S Starting point of substring to start factoring
Now big-S is stringfile and I don't see a searchstring-option, is it gone?
(workaround is easy enough, just deleting the part up to searchstring
in my Pi1Mio-file)

2. what does '-t --nthreads=N Start N threads' do in the CL-version?
CPU threads preparing stuff / feeding the GPU?
Doesn't seem to make any speed differences.
1) -S doesn't exist in pixsievecl, but I can create it. It will not use the -S option for that though. The workaround is easy enough for an end user so I didn't include it. If you "had" to, use pixsieve to create an output file, then continue with pixsievecl.

2) -t will change the number of concurrent GPU threads. If you can't run with enough blocks to keep the GPU busy, then increase the number of threads. When the program ends it tells you how much time was spent in the GPU and how much time it was waiting for the GPU before giving it more work. If the percent of time waiting for the GPU is low, add more threads.
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