Date: Mon, 5 Apr 1999 16:09:50 -0700 (PDT) From: <unknown@riverstyx.net> To: Mark Ovens <marko@uk.radan.com> Cc: Greg Lehey <grog@lemis.com>, Leif Neland <leif@neland.dk>, FreeBSD Questions <questions@FreeBSD.ORG> Subject: Re: K6-2/333, was: Re: Debug kernel by default (was: System size with -g) Message-ID: <Pine.LNX.4.04.9904051605450.10244-100000@hades.riverstyx.net> In-Reply-To: <19990406001645.I1360@marder-1.localhost>
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I may be out to lunch on this one, but I'm pretty sure that the multiplier is for the internal clock of the chip. So, if, after applying the multiplier to one chip you get 300MHz, and after applying a different multiplier to a different chip with a different bus speed you also get 300MHz, you get two chips that perform the exact same number of operations/sec. The difference is the bus speed, which affects I/O performance, etc. A 100 MHz bus with a x3 multiplier will outperform a 66 MHz bus with a x4.5 multiplier because the CPU will have to wait more often when it wants to fetch non-cached data from RAM. Most boards have the multiplier done through jumpers, so the chip can hardly decide whether or not to honor the multiplier settings -- the oscillator will simply operate at X MHz. --- tani hosokawa river styx internet On Tue, 6 Apr 1999, Mark Ovens wrote: > > >> 95 MHz / 3.5x is only required if you don't want to "underclock" your > > >> processor. It is probably not required to run the processor at all. > > > > > > Sorry, I don't understand what you are saying. Doesn't 95MHz and > > > 3.5X give 332.5MHz, which is ~333MHz, the specified processor speed? > > > > Well, yes. So do 66 MHz and 5X, and 75 MHz and 4.5X, and 83 MHz and > > 4X. > > > > Yes. I don't dispute that they equate to the same speed, but does > it have the same end result, i.e. the CPU can do the same number > of calculations per unit time? This is not a rhetorical question, > I'm interested to know the answer. The fact that AMD say 95MHz & > 3.5X but don't add "or 66MHz & 5X" suggest that they are not the > same. Does the CPU actually understand being told to use 5X and if > not, does it then not use *any* multiplier (and just run at 1X)? To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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