GMPbench results for Core i7

Torbjorn Granlund tg at
Sat Jul 25 12:29:56 CEST 2009

I have run GMP 4.3 on a 2.7 GHz Core i7, the latest spin of the
P6 core from Intel.

The processor compiles GMP amazingly fast, faster even than a
high-end AMD system, in just 14 seconds.  But Intel does not
optimise their processors for the kind of instructions we need in
GMP, and the GMPbench results are a bit disappointing.  Please

I though the corei7 was just an improved core2, but timing the
GMP innerloops indicates that it is more-or-less a different

                                Core2   Corei7  AMDk10
mpn_add_n/mpn_sub_n             2.03    2.3     1.5
mpn_lshift/mpn_rshift           1.27    1.75    2.37
mpn_mul_1                       4.0     3.8     2.5
mpn_addmul_1/mpn_submul_1       4.5     5.0     2.5
mpn_divrem_1                    25      21      13

The corei7 is sometimes faster, sometimes slower than core2, but
the two processors never seem to execute any of the assembly
inner loops exactly equally.


More information about the gmp-discuss mailing list