Date: Thu, 14 Dec 2000 00:51:48 -0600 (CST) From: Mike Meyer <mwm@mired.org> To: kstewart@urx.com Cc: questions@freebsd.org Subject: Re: advice with old equipment. Message-ID: <14904.28164.273218.788343@guru.mired.org> In-Reply-To: <3A3862E1.A0D6E0C2@urx.com> References: <14904.1150.593498.981432@guru.mired.org> <3A381379.9F464204@urx.com> <14904.20712.193427.889148@guru.mired.org> <3A3862E1.A0D6E0C2@urx.com>
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Kent Stewart <kstewart@urx.com> types: > Mike Meyer wrote: > > Salespeople love CPU clock speed - it gives them a single number to > > feed to consumers to make their product look good. The reality is > > *much* more complicated, though. My 400MHz PII/Xeon blows the doors > > off my 500MHz K6-2. But a 500MHz PIII w/512K of cache would outperform > > the Xeon - and the pricing on the chips reflects that. > I always thought a Xeon with 4MB of cache memory would be pretty > awesome in a server. I'm looking at upgrading my Xeons to 2MB - I haven't seen the 4MB version anywhere. Is it a PIII thing, or otherwise incredibly expensive? > > > A buildworld on the Celeron 433 is a little bit faster than a > > > buildworld on a Abit BX6 rev 2 with a P-II 400. The Abit board is > > > about 10% slower than a SuperMicro with the same speed cpu. Never have > > > figured that one out. > > What's the cache size on the two P II systems? 256K vs. 512K, maybe? > They are all 512k. I have been going to replace one of them with a > coppermine to see what that does. A number I read was that throughput > vs clock speed was linear up to about 3x the FSB. Interesting claim. Not sure I believe it, though. Of course, there may be some unstated assumptions (cache size and application load, for instance) that make it true. > At some point after that, the cpu was spending time waiting for data > and cache would really become important for some types of > computations. On my systems currently, it is a 1/2 speed, full size > cache on the P-II's/III's and a 1/4 size, full speed cache on the > Celeron 433a. I had a 300a that I overclocked to 450 until it > died. For about 2 months it out performed a P-III 450. It died from > overheating building XFree86 3.3.4 after one of the releases. A > trivia point is that adding PC-100 memory to the Celeron's speeded > them up about 15%. You can get back some of the 150% you lose > because of the cache and FSB. I thought the PIIIs had full speed caches. > I got interested in the AMD Athlon because of the additional pipelines > that the Intel Pentium's didn't have. I thought pipelines were > important on the old Cray and a good algorithim would help the PC. Pipelines were important on the old Crays. However, the important pipline was in the array processors, not the CPU. When they did array operations, the data from the input arrays were pipelined through the array processor so that you could do hundreds of flops at the rate of one per machine cycle. The CPU was pretty much RISC, which made all the instruction decode stuff fast. For something like an AMD, the work that led to the MIPS (IIRC, that's a machine *without* Interlock Pipeline Stages - the compiler was supposed to make sure the there were no bubbles in the pipeline, so the hardware didn't have to, and hence could run faster) might be more relevant. > The > Athlon 900's are pretty fast. I have an old Micron Millennia P-200 > with 128MB of 60ns EDO. It is ~15.5 times slower doing a Seti workunit > (wu) than the Athlon 900 with 256MB of PC-133 memory. The times are on > the order of 277,xxx secs vs 17,8xx secs with a lot of variation on > both sides. It was a wu every 3+ days vs 4.8+/day. I will see what > they work out to be after a 100 or so. The Micron has been cranking > for 1.6 years and the Athlon is catching up fast. Hmm - that's close to linear with my Xeons, which are averaging around 37,4xx. Since the Athelon costs about half what a PIII does, that makes it a bargain for seti@home wu's. <mike -- Mike Meyer <mwm@mired.org> http://www.mired.org/home/mwm/ Independent WWW/Unix/FreeBSD consultant, email for more information. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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