Sender: law AT sgi DOT com Message-ID: <38AD6A13.AA6FA791@sgi.com> Date: Fri, 18 Feb 2000 07:49:39 -0800 From: Linda Walsh X-Mailer: Mozilla 4.7 [en] (X11; I; Linux 2.2.14 i686) X-Accept-Language: en MIME-Version: 1.0 To: Marc Lehmann CC: pgcc AT delorie DOT com Subject: Re: Big slowdown on -mpentium/-mpentiumpro, short_int add References: <38AC20C0 DOT 55E33FA4 AT sgi DOT com> <20000218130553 DOT C1399 AT cerebro DOT laendle> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Reply-To: pgcc AT delorie DOT com Marc Lehmann wrote: > > On Thu, Feb 17, 2000 at 08:24:32AM -0800, Linda Walsh wrote: > > Showed about a 30-40% slowdown when using the -mpentium or -mpentiumpro > > on which cpu, and slowdown compared to what? --- on a Pentium-III. Flags fast on short_int: CCOPT=-O2 -fomit-frame-pointer -m486 -malign-loops=2 -malign-jumps=2 -malign-functions=2 -DCPU=686 vs. Adding the -mpentiumpro or -mpentium to the above set. > > Note the test suite is copyright, but I'm excerpting this section for > > educational (to demonatrate a problem) purposes. > > Das that make it more legal ;) Anyway, thanks a lot for the snippet! --- Under copyright law, excerpting bits for educational purposes is permitted! :-) Education is a protected area. Another is for purposes of a review of an article or something (unless UTICA passes, then all bets are off). I can see a post-UTICA world where books are not sold to people, but "licensed" -- and the terms of the license would prohibit any review critical of the work. Oi vey. > I do not know the reason for the slowdown (yet), but "short" is about > the slowest datatype for pentium-type systems, and it could very well be > that suboptimal scheduling even of a single insns can make such a large > difference. --- I also have some P-II's here, I can try it on that later when I get the time. I hadn't had time to dump assembler and peek yet either, My work has only been sucking up most of my brain lately...:-) -l