From owner-freebsd-hackers Tue Apr 4 16:04:14 1995 Return-Path: hackers-owner Received: (from majordom@localhost) by freefall.cdrom.com (8.6.10/8.6.6) id QAA25522 for hackers-outgoing; Tue, 4 Apr 1995 16:04:14 -0700 Received: from cs.weber.edu (cs.weber.edu [137.190.16.16]) by freefall.cdrom.com (8.6.10/8.6.6) with SMTP id QAA25514 for ; Tue, 4 Apr 1995 16:04:13 -0700 Received: by cs.weber.edu (4.1/SMI-4.1.1) id AA20914; Tue, 4 Apr 95 16:55:48 MDT From: terry@cs.weber.edu (Terry Lambert) Message-Id: <9504042255.AA20914@cs.weber.edu> Subject: Re: PCI/EISA/ISA performance To: matt@lkg.dec.com (Matt Thomas) Date: Tue, 4 Apr 95 16:55:48 MDT Cc: vernick@cs.sunysb.edu, freebsd-hackers@FreeBSD.org In-Reply-To: <199504041833.SAA10697@whydos.lkg.dec.com> from "Matt Thomas" at Apr 4, 95 06:33:32 pm X-Mailer: ELM [version 2.4dev PL52] Sender: hackers-owner@FreeBSD.org Precedence: bulk > > 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.