Re: [ROOT] icc versus gcc ?

From: Victor Perevoztchikov (perev@bnl.gov)
Date: Tue May 21 2002 - 15:47:25 MEST


Hi Fons,
>   there remains one problem with the icc compiler in one CINT routine in
what about icc debugger. The latest version gdb does not work at all for
gcc.
Is it the same for icc?

Victor

Victor M. Perevoztchikov   perev@bnl.gov
Brookhaven National Laboratory MS 510A PO Box 5000 Upton NY 11973-5000
tel office : 631-344-7894; fax 631-344-4206; home 631-345-2690

----- Original Message -----
From: "Fons Rademakers" <Fons.Rademakers@cern.ch>
To: "Ahmet Sedat Ayan" <ayan@cms.physics.uiowa.edu>
Cc: <roottalk@pcroot.cern.ch>
Sent: Tuesday, May 21, 2002 4:26 AM
Subject: Re: [ROOT] icc versus gcc ?


> Hi Ahmet,
>
>   there remains one problem with the icc compiler in one CINT routine in
> -O mode. This problem has been localized and reproduced in a small test
> program and Intel is working on a fix. In the ROOT makefile I've added a
> protection such that this file is always compiled in -O0 mode while the
> rest of ROOT is compiled in -O (i.e. -O2) mode. I retract evrything I
> said about icc in the April 8th mail, since a lot of confusion was based
> on a misunderstanding of the icc man pages in relation to building
> shared libs. I use icc as default compiler on my machine.
>
> Cheers, Fons.
>
>
>
> On Mon, 2002-05-20 at 22:47, Ahmet Sedat Ayan wrote:
> >
> > 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
> >
> --
> Org:    CERN, European Laboratory for Particle Physics.
> Mail:   1211 Geneve 23, Switzerland
> E-Mail: Fons.Rademakers@cern.ch              Phone: +41 22 7679248
> WWW:    http://root.cern.ch/~rdm/            Fax:   +41 22 7679480
>



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