Dear Rooters, I have been investigating if I should be re-compiling/installing my ROOT with Intel's "icc". In the roottalk I think there are conflicting opinions on the performance and/or worthiness of this (see the messages below by Fonds) I have a Redhat7.2 Linux box with a P4 1.8 GHz processor and running my analysis code (no GUI etc involved); reading data from the disk (I/O) , calculating same variables and filling and plotting many histograms. (Whole data run takes about 3-4 hours) My question is then if it is worth to compile ROOT with "icc" and if I did if I would see a big improvement in the analysis code running time?? thanks a lot ahmet **************************************************************** May,14,2002 ROOTers, with the current version of ROOT in CVS we now fully support the latest Intel icc v6 compiler. This compiler provides about 30 to 45% faster code then gcc 2.95 or gcc 3.x on Intel PIII and P4 systems. The Linux version of this compiler can be freely downloaded from: http://www.intel.com/software/products/eval/ (get the "non-commercial unsupported software" version which is free). With ROOT on my P4 machine this compiler produces 35% faster code (both in debug and optimized mode). At the same time it compiles also about 20-30% faster than gcc. To install ROOT do: ./configure linuxicc; make For more on this compiler see also: http://www.open-mag.com/features/Vol_15/IntelC/intelc.htm It is nice to see your good old PC suddenly run 35% faster. Cheers, Fons. **************************************************************************** On April,8th,2002 Hi Andre, your observations are correct. Concerning icc (and ecc, the IA-64 version of icc), I have several incident reports open with Intel concerning the compiler failing on ROOT's very conservative C++ code. Actually the icc v6beta cannot even execute ROOT because it generates in all cases (-g, -O, etc) bad code. This Intel compiler has its origins as Intel's SPEC reference compiler, i.e. it has been optimized and tuned with the sole goal to produce the best binaries for the SPEC program suite (rumour has it it could even generate SPEC binaries without input source code, i.e. the binaries were hand coded and included in the compiler proper). Cheers, Fons. ---------------------------- *************** Ahmet Sedat Ayan Physics & Astronomy Dept. Van Allen Hall University of Iowa Iowa City, IA, 52242 Voice : (++ 1 319) 335-1941 (W) (GMT-6) Occupation : Ph.D Candidate (But still dreamer!) e-mail : ayan@cms.physics.uiowa.edu web : http://jazz.physics.uiowa.edu/~ayan
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