On Saturday 18 May 2002 2:55 am, you wrote: >> >On Thu, 2002-05-16 at 11:12, Matt Palmer wrote: >> >> >> Fons Rademakers writes: >> >> >> > with the current version of ROOT in CVS we now fully support >> >> >> > the latest Intel icc v6 compiler. > >Matt Palmer wrote: >> I've now had success with this - I think it must have been a problem due >> to not being able to do a proper install if icc. The great thing is I've >> seen a 30% speed increase just from changing compiler! > >Hi Rooters - it would be really nice if somebody who has already installed > icc and built ROOT with it would also post to the list comparison of the > sizes of ROOT libraries as compiled with icc and gcc. Would be a very > important piece of information. Just for comparison - what we are seeing at > CDF (we're currently using KAI compiler, KAI was bought by Intel not so > long ago) is that when we compile our code in debug mode, then the > GCC3-compiled libraries are larger than the KAI-compiled libraries by a > very large - 5-10 times - factor (although the code is rather heavily > templated...) I compiled root from CVS with icc and found the root/lib directory to be 50Mb compared to the downloaded binaries compiled with gcc2.96 which were 24Mb. ROOT was compiled with all default options which were I think just -O. This is slightly odd tho, as in recompilation of my own code with icc, I've noticed a slight drop in size (~20%). I have been using the following options for icc: -O3 -tpp6 -axiKW. Which generates platform specific code for P4s, P3s and P2s. I suspect that was the reason for the massive speed increase when running on a P4 - the ability to use the SSE2 instruction set. Hope this is helpful Matt
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