Wojciech Florek <[EMAIL PROTECTED]> writes: >I've compiled Mlucas 2.7y on R4600 SGI IRIX 6.5 machine with >MIPSpro Compilers: Version 7.2.1.3m . >Machine data: > > Powered by Silicon Graphics > > CPU MIPS R4600 Processor Chip Revision: 2.0 > FPU MIPS R4600 Floating Point Coprocessor Revision: 2.0 > 1 133 MHZ IP22 Processor > Main memory size 128 Mbytes > Secondary unified instruction/data cache size 512 Kbytes on Processor 0 > Instruction cache size 16 Kbytes > Data cache size 16 Kbytes > >MacLucasUNIX writes checkpoints after each 5000 iterations, what makes >about 2h 20 min (it isn't `clean' CPU time but almost 98% of CPU was >devoted to MacLucasUNIX), so I've run Mlucas 2.7 for the same exponent and >5000 iterations (MacLucasUNIX was stopped so almost all CPU time was >assigned to Mlucas). Here are the results > > Enter p,n (set n=0 for default FFT length) > 3355031,262144 > Enter 'y' to run a self-test, <return> for a full LL test > y > Enter number of iterations for timing test> 5000 > p is prime...proceeding with Lucas-Lehmer test... > M( 3355031 ): using an FFT length of 262144 > this gives an average 12.798427581787109 bits per digit > INFO: Using real*16 for FFT sincos and DWT weights tables inits. > 5000 iterations of M 3355031 with FFT length 262144 > Res64: 6E592176A2A59208. Program: E2.7y > Clocks = 01:49:34.963 > >About 30 min faster! That's encouraging - now try the same exponents at runlength 192K (196608) - you should get the same Res64, but your time should be even better. >I've used the options provided in the source file and haven't played >with them. Make sure you use -r4600 rather than -r10000, and -mips{whatever generation R4600 is, probably 2 or 3) rather than -mips4. Your timing corresponds to 1.32 sec/iteration, compared to 0.185 sec at 256K for the same code on a 250MHz MIPS R10000 - even after adjusting for the faster clock speed of the latter and accounting for the fact that the R10000 is a more advanced processor, I think you should be able to get somewhat better performance out of your R4600. If you do find flags that give better performance, let me know. >Some remarks: > 1. In the interactive mode entering <return> instead of `y' causes > a misprint in comments: > Enter p,n (set n=0 for default FFT length) > > Enter 'y' to run a self-test, <return> for a full LL test > > p is prime...proceeding wit >!! >>>>> a line is broken here! It doesn't happen when I replied `y' That sounds like a compiler error, but there's an easy workaround - for full LL tests you should be entering exponents into the worktodo.ini file anyway, and that avoids having to enter any input. >2. For small Mersenne exponents an `exit carry' error occurs. It's > happened for M787 & M797 > > M( 797 ): using an FFT length of 512 > this gives an average 1.556640625 bits per digit > > INFO: Using real*16 for FFT sincos and DWT weights tables inits. > FATAL: iter= 225 nonzero exit carry in radix16_ditN_cy_dif1. The carry propagation routines in Mlucas assume that any "wraparound" carry left over when one gets to the most-significant digit of the residue vector will propagate no further than 4 digits into the low end of the residue, i.e. that (exit carry) <= 2^(4*radix). If you use a very small radix as in the above the case, this assumption may no longer be true. >I know that these exponents have been tested, but there is a question >whether it may happen for larger mersennes? There shouldn't be any problem with large exponents (> 5000, say) since for large p, one always has an available FFT length which is well- matched to the number in question, i.e. gives > 10 bits per digit. >3. My LL (double checking) tests on IRIX machines with MacLucasUNIX > are in progress (50% and 75%). I think that there is no possibility > to switch to Mlucas during tests and starting from the begining Indeed there is not - if your MLU runs are > 25% complete, finish them using MLU and use Mlucas for subsequent tests. On the other hand, if you find a greater speed gain using 192K runlength and/or better compile options, the above 25% breakover threshold will be increased. Happy hunting, -Ernst _________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers