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Re: Do we get the other 15% performance back too?
- From: Andreas Jaeger <aj at suse dot de>
- To: Burkhard Militzer <militzer at llnl dot gov>
- Cc: <gcc at gcc dot gnu dot org>
- Date: Mon, 26 Aug 2002 18:47:36 +0200
- Subject: Re: Do we get the other 15% performance back too?
- References: <Pine.LNX.4.33.0208260923090.3598-100000@dresden.llnl.gov>
Burkhard Militzer <militzer@llnl.gov> writes:
> Hello,
>
> As a fan of the C++ gnu compiler project, I would like to congratulate the
> gurus on the recent performance increase probably coming from corrections
> in the prefetch routines. My benchmark shows
-O3 does not use prefetching it all.
Can you destill some small testcase that shows the problems?
Andreas
> Processor/OS Compiler/options Time(sec)
> Pentium 4 1.7Ghz pgCC -O3 -fast -Minline=3/4 8.27
> Pentium 4 1.7Ghz gnu g++ -O3 (2.95.2) 8.62 <-- fastest
> Pentium 4 1.7Ghz Intel icpc 5.0 -O3 8.65
> Pentium 4 1.7Ghz gnu g++ -O3 (2.95.3) 10.94
> Pentium 4 1.7Ghz gnu g++ -O3 (3.2) 11.30 <-- new
> Pentium 4 1.7Ghz gnu g++ -O3 (3.01) 15.09 <-- previous
>
> The improvement from 3.01 to 3.2 are significant but it their a way of
> somehow getting the performance of 2.95.2 back?
>
> Anyway, great work! Thanks a lot,
>
> Burkhard Militzer
>
> For comparison:
>
> DEC Alpha 1GHz KCC kcc3.4d -O3 5.2
> DEC Alpha 667MHz KCC kcc3.4g2 -O3 8.4
> DEC Alpha 667MHz g++ -O3 (2.96?) 10.3
> DEC Al-Linux 667Mhz g++ -O3 (2.96?) 14.66
> O2K R10000 KCC -O3 +K3 --no_exceptions 18.26
> IMB SP2 332MHz KCC kcc3.4d -O3 +K3 27.56
>
>
--
Andreas Jaeger
SuSE Labs aj@suse.de
private aj@arthur.inka.de
http://www.suse.de/~aj