Re: Intel compiler [Re: Using %cr2 to reference "current"]

lists
2001-11-07T22:06:16Z

Just as another data point - a simple test, I ran intel
compiler on flops v2.

Run 3 ways - gcc3, icc (v 5) and the beta 6 icc. All run
on dual p4 with 1 Gb mem on Rh 7.2

At least on this test the differences are quite dramatic.

Regards,

gene/

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Summary
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gcc -DUNIX -O3 -march=i686 flops2.c
icc -xMKW -o flops2 -DUNIX -O3 flops2.c

FLOPS C Program (Double Precision), V2.0 18 Dec 1992

Module MFLOPS
gcc icc 5 icc 6
-------- --------- ----------
1 444.9410 439.4850 674.3180
2 265.4815 362.3862 362.3862
3 298.1843 604.0250 1270.6569
4 337.7309 1224.8804 1373.8819
5 392.7003 1138.6503 1131.7073
6 391.7678 1334.0521 1422.2222
7 163.5783 193.3900 193.5118
8 395.7743 1317.3242 1372.6542

Iterations = 512000000 512000000 512000000
NullTime (usec) = 0.0029 0.0000 0.0000
MFLOPS(1) = 275.3542 416.9120 472.8952
MFLOPS(2) = 264.7165 413.4297 448.2175
MFLOPS(3) = 339.5966 714.7146 834.5651
MFLOPS(4) = 362.1891 1071.8196 1367.5374

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On Wed, Nov 07, 2001 at 03:39:46PM +0100, Sebastian Heidl wrote:
> On Wed, Nov 07, 2001 at 02:17:33PM +0000, Alan Cox wrote:
> > > somehow encouraged by the compiler comparisions between gcc and intel's
> > > free compiler, which use the register passing for anything local
> > > to the actual code, where the speed gains are up to 20% im currently
> >
> > I was under the impression intels compiler was profoundly non-free ?
>
> have a look:
> http://developer.intel.com/software/products/eval/