Karim BELABAS on Sun, 21 Sep 2003 13:01:41 +0200 (MEST) |
[Date Prev] [Date Next] [Thread Prev] [Thread Next] [Date Index] [Thread Index]
Re: performance comparison |
On Sun, 21 Sep 2003, Igor Schein wrote: > I ran nfgaloisconj(degree-92 pol) on 3 different platforms: > > Tru64 on 1GHz ev68 compiled with cc 99s > Linux on 2.4GHz athlon compiled with gcc 220s > Linux on 3.0GHz P4 compiled with gcc 302s > > I used --with-gmp for compilation of latest CVS sources and the > initial stack was 256m. > > I can see 2 things here, that P4 does lose in comparison to Athlon, > and that Alpha is a clear winner. Am I correct in assuming that this > is essentially a benchmark of floating point performance, where Alpha > is way superior, or does Alpha's large cache play the role in the > equation? Or maybe gcc-vs-cc proposition is the factor here? > > In fact, I suspect that Pari's benches are dominated by integer > arithmetic, making P4 the fastest platform, while most number field > operations are floating point internsive. Since number fields are > bread-and-butter of Pari... There's almost no (hardware) floating point arithmetic in PARI. Everything is integer arithmetic. What is true is that Pari's benches are dominated by _single precision_ integer arithmetic. With intensive multiprecision like the above, it makes sense that the 64 bit machine outperforms the others. I would also assume that cache size plays some (less important) role since most of the data is connected with sequential access. How does the above translate 1) without gmp ? [ my guess: alpha timings will be bad... ] 2) for smaller nfgaloisconj (possibly in a loop to get useful timings) ? 3) for a basic operation like p = 50000; default(realprecision, p); a = round(log(2)*10^p); b = a + 1; gettime(); for(i=1,100,a * b); gettime() [ you'll be mostly profiling GMP here ! ] 3) Anything weird when profiling the above run ? Cheers, Karim. -- Karim Belabas Tel: (+33) (0)1 69 15 57 48 Dép. de Mathématiques, Bât. 425 Fax: (+33) (0)1 69 15 60 19 Université Paris-Sud http://www.math.u-psud.fr/~belabas/ F-91405 Orsay (France) http://www.parigp-home.de/ [PARI/GP]