Date: Thu, 01 Jun 2000 14:29:21 -0400 From: Dennis <dennis@etinc.com> To: Warner Losh <imp@village.org> Cc: Mike Smith <msmith@FreeBSD.ORG>, Joy Ganguly <joy@niksun.com>, freebsd-hackers <freebsd-hackers@FreeBSD.ORG> Subject: Re: S5933 PCI Adapter..?? Message-ID: <200006011829.OAA03264@etinc.com> In-Reply-To: <200006011813.MAA30293@harmony.village.org> References: <Your message of "Thu, 01 Jun 2000 11:18:36 EDT."<200006011518.LAA02647@etinc.com> <200006011518.LAA02647@etinc.com> <Your message of "Fri, 26 May 2000 11:45:18 EDT." <392E9C0E.4B9EB0FB@falcon.niksun.com>
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At 12:13 PM 6/1/00 -0600, Warner Losh wrote: >In message <200006011518.LAA02647@etinc.com> Dennis writes: >: Have you done bus performance testing with this card? Given the >: architechture of the AMCC part, it seems highly improbable that you will be >: able to get high throughput with such a card. Because the AMCC part >: requires external logic it is impossible to do pass-through single cycle >: bursts, which is required for efficient utilization of the PCI bus. Once >: you begin holding off cycles the PCI bus totally pigs out (which is why >: virtually all high-speed pci solutions are single-chip type designs). > >Yes. I've done drivers for several cards with this design. The AMCC >part is very fussy and will often lock up the bus unless the card >designer has put enough extra logic on the card to cope with the >oddities of the card. Sadly, many don't. We used it on our first (and now defunct) pci board, and we didnt have trouble with lockups (there are quite a few errata that have to be addresses), but the arbitration was pitifully slow. There was no way to get high throughput across the bus. We completely rejected it for use on T3...i find it interesting that someone did an OC3/ATM card with it. Dennis Emerging Technologies, Inc. ---------------------------------------------------------------------------- --------- http://www.etinc.com ISA and PCI T1/T3/V35/HSSI Cards for FreeBSD and LINUX Multiport T1 and HSSI/T3 UNIX-based Routers Bandwidth Management Standalone Systems Bandwidth Management software for LINUX and FreeBSD To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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