Date: Tue, 4 Apr 95 16:55:48 MDT From: terry@cs.weber.edu (Terry Lambert) To: matt@lkg.dec.com (Matt Thomas) Cc: vernick@cs.sunysb.edu, freebsd-hackers@FreeBSD.org Subject: Re: PCI/EISA/ISA performance Message-ID: <9504042255.AA20914@cs.weber.edu> In-Reply-To: <199504041833.SAA10697@whydos.lkg.dec.com> from "Matt Thomas" at Apr 4, 95 06:33:32 pm
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> > Anyone have any performance results comparing the three types of > > buses? I'm interested in disk I/O performance and/or network > > I/O performance using the three buses and DMA. > > As a rule of thumb, PCI > EISA > ISA. Whose thumb are you looking at? 8-). VLB has a speed limit of 40MHz (typical cards die > 33MHz, though) PCI has a speed limit of 33MHz ISA has a speed limit of 12MHz EISA has a speed limit of bus clock (mine runs at 50MHz) PCI has a width limit of 64bits EISA has a width limit of 32bits VLB has a width limit of 32bits ISA has a width limit of 16bits (AT) or 8bits (XT) EISA and VLB fall back to 16/8 (ISA) depending on the card So which is faster depends on your relative bus clock rate (it has to be pretty high to beat PCI, however). For instance, a DX4/75 PCI has the same bus transfer rate as a DX/50 EISA. Actually, MCA looks pretty good, compartively. 8-). Terry Lambert terry@cs.weber.edu --- Any opinions in this posting are my own and not those of my present or previous employers.
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