>From: "Samuel H. Lipoff" <[EMAIL PROTECTED]> >Date: Thu, 07 Jan 1999 20:14:44 -0500 >Subject: Mersenne: Re: Mersenne Digest V1 #491 > >"Brian J Beesley" <[EMAIL PROTECTED]> wrote: > >> I'd be VERY interested to hear of anyone running Prime95 on a >> Xeon - the Xeon has 512K, 1M or 2M of L2 cache running at core >> speed (at painful, extortionate and positively obscene prices, >> respectively) - benchmark comparisons with PII systems at the same processor/bus speed would be >> interesting! > As Samuel Lipoff and Aaron Blosser have reported, they see some measurable performance improvement when comparing XEON CPUs with plain vanilla PIIs. I have a PII Overdrive, which is basically a PII XEON in a different package such that it fits socket8 (PPro) motherboards, i. e. this CPU has 512KB L2 cache running at core speed and a deschutes core, just like the PII XEON. However, it runs only at 66*5 = 333MHz. On my machine (dual board, 1 CPU, 440FX chipset, 256MB ECC EDO) my "RollingAverage" value is constantly around 850 (before the upgrade, this number was usually around 970), even if I leave the machine mostly alone (I have not done any precise measurement of "time/iteration" though). That is despite the fact that - as others have seen in the case of the XEON CPUs - the setup program overestimates the clock rate of the CPU (in my case only by a mere 10%, however, if memory serves). Any ideas where the difference comes from? Poor memory performance of the FX chipset? Penalty for extra writes due to ECC? BTW, has anybody any performance values of Celeron300A CPUs running at 450MHz? In general, given the same L2-cache speed, how much of an impact would the smaller size (128KB vs. 512KB in the XEONs) have? Martin
