Date: Mon, 22 Mar 1999 12:07:02 -0500 From: Dennis <dennis@etinc.com> To: Mike Smith <mike@smith.net.au> Cc: Amancio Hasty <hasty@rah.star-gate.com>, hackers@freebsd.org Subject: Re: Gigabit ethernet -- what am I doing wrong? Message-ID: <199903221711.MAA20551@etinc.com> In-Reply-To: <199903220200.SAA02330@dingo.cdrom.com> References: <Your message of "Sun, 21 Mar 1999 20:10:21 EST." <199903220058.TAA17538@etinc.com>
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At 06:00 PM 3/21/99 -0800, Mike Smith wrote: >> At 12:13 PM 3/21/99 -0800, you wrote: >> > >> >Hmm.... >> >Does anyone know when the faster PCI busses (64bits or 66MHz PCI clock rate) >> >are going to be availabe ? >> >> The "availability" of 66Mhz busses is almost moot. Making ASICs work at 33mhz >> is a chore....66mhz is a waze off. > >That's close, but several of the major ASIC vendors were (or were >claiming to be) sampling devices with 66MHz PCI macrocells the last time >I looked. Any names? the vendors will be few, I think, for awhile. >> And as far a 64 bit busses.....there >> arent many >> processors that can do is, and doubling the bandwidth on a 32bit processor >> isnt >> always linear in performance. You have to get a whole new generation of >> processors before you will see any usable products. > >This has nothing whatever to do with reality, however. Most PCI >peripherals are bus masters, and most memory busses these days are at >least 64 bits wide, so 64 bit PCI has very real performance benefits. > >The processor's internal word size has little or nothing to do with the >equation. The ability to do single-cycle transfers IS affected by the internal processor's word size. If it can't do sustained single-cycle bursts then performance suffers significantly, so I disagree wholeheartedly on this. If the on-board processor doesnt have a 64bit bus it is very difficult to do single cycle transfers. Dennis To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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