Date: Mon, 6 Oct 1997 17:41:13 +0300 (EEST) From: Narvi <narvi@haldjas.folklore.ee> To: "Serge A. Babkin" <babkin@hq.icb.chel.su> Cc: Robert Swindells <rjs@fdy2.demon.co.uk>, hackers@FreeBSD.ORG Subject: Re: PCI slowness ? Message-ID: <Pine.BSF.3.96.971006173900.25822A-100000@haldjas.folklore.ee> In-Reply-To: <199710051540.VAA09237@hq.icb.chel.su>
next in thread | previous in thread | raw e-mail | index | archive | help
On Sun, 5 Oct 1997, Serge A. Babkin wrote: > > > > > > > The chipset is Intel Triton on some chineese motherboard > > > with 75MHz Pentium, memory is 60ns EDO. > > > Theoretical PCI throughput is 33M > > > of 4-byte transfers per second (the card claims to work > > > in burst mode). Theoretical memory throughput is at least > > > 10M of 4-byte transfers per second if we suppose that > > > the memory cycle with all overhead is 100ns and the > > > card reads by 4 bytes at a time. But the experiment > > > shows throughput of only 17MBps or 4.25M of 4 byte > > > transfers. Does the processor eats all the remaining > > > throughput (although I think it must load most of the > > > code it runs at idling into the cache) ? > > > > I thought that a 75MHz Pentium ran the PCI bus at 25MHz, not 33MHz. > > > > Are you sure that the bus on your system is at 33MHz ? > > No, I am not. But the motherboard has possibility to generate 33MHz > and if I were the designer of this card I would use this clock > independently of the processor clock. *ALL* intel chipsets made to date get their PCI bus frequency by dividing the bus frequency with two. For pentium 75, the motherboard (memory bus) speed is 50Mhz and the PCI speed is 25Mhz. The designer of the board has no joice. Sander There is no love, no good, no happiness and no future - all these are just illusions. > > -SB >
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?Pine.BSF.3.96.971006173900.25822A-100000>