Newsgroups: comp.os.msdos.djgpp From: Elliott Oti Subject: Re: Speed problems with AMD K6 Sender: usenet AT fys DOT ruu DOT nl (News system Tijgertje) Message-ID: <34C410BF.EB7@stud.warande.ruu.nl> Date: Tue, 20 Jan 1998 02:49:35 GMT Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=us-ascii References: <69ocb5$4dt$1 AT nclient5-gui DOT server DOT virgin DOT net> Mime-Version: 1.0 Organization: Bipolar Widgets International Lines: 39 To: djgpp AT delorie DOT com DJ-Gateway: from newsgroup comp.os.msdos.djgpp Precedence: bulk Gary Smith wrote: > > Help.. > > I have just changed my CPU from a Cyrix 6x86 P166+ to an AMD K6 166MHz, and > have noticed a drop in performance with programmes written using using DJGPP > and Allegro. The drop in performance is in the region of 20%. > > I have benchmarked the AMD and the Cyrix using Wintune 97, and in all the > tests the AMD is faster than the Cyrix. eg: > > Floating Point Performance (MFLOPS) > ------------------------------------------------------- > AMD K6 P166 98 > Cyrix 6x86 P166+ 52 > > Integer Performance (MIPS) > ----------------------------------------- > AMD K6 P166 320 > Cyrix 6x86 P166+ 250 > > Does anyone have any ideas as to the cause of the performance drop with the > AMD CPU ? Could be the system bus clock speed. What speed is it running at? For instance, I have a AMD 486 DX4-100 ( bus speed 33 MHz) and a Cyrix 486 DX2-80 ( bus speed 40 MHz), and the DX2-80 blits consistently faster than the DX4-100, despite its slower CPU ( the rest of the hardware is identical). I don't know what speed the AMD and Cyrix boards are _really_ running at ( I think the Cyrix 166+ runs at 133 MHz, with a 66 MHz bus clock; could be the AMD system bus runs at 40Mhz ). It could simply be that Cyrix motherboards have better buses than AMD. Then again, it could be a software problem; are you running your djgpp progs under a different DPMI host on the AMD than on the Cyrix? -- ------------ Elliott Oti --------------- ------------- http://www.fys.ruu.nl/~oti ---------