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SMP Linux on the Cheap

Posted by CmdrTaco on from the two-scoops-of-CPU dept.

d^2b writes "There is an article using dual Celerons under Linux on cpureview.com. This is even more attractive now that you can buy an Abit BP6 for $130 and plug two socket 370 Celerons into it directly. The good news is that that author gets 183% speedup over a single processor compiling the kernel. "

2 of 114 comments (clear)

  1. The memory bottleneck by Admiral+Burrito · · Score: 3

    The idea of using Celerons only works if you can overclock them. It may go well for hacks and tinkers, but for the heavy video and I/O, a 66Mhz bus frequency is unacceptable.

    In the article, the guy ran one of the chips at 2.1 volts... I wonder how long it stayed stable at that speed/voltage. I have a C300A that runs perfectly stable at 450 MHz 1.9v, but crashes regularly if I use default 2.0 voltage. These PPGA Celerons don't dissipate heat as well as their Slot-1 brothers can.

    I would expect memory bandwidth to be an issue with SMP Celeron systems, especially if you're not overclocking. The last part of the article touched on this, but I think a lot of people still don't get it...

    The Celerons only have 128k cache, compared to 512k on the P2. The Celeron cache runs at twice the speed of the P2 cache, often resulting in better single-processor performance, but because the Celeron cache is smaller it has to go to RAM more often. This means that the Celerons consume more memory bandwith than the P2s.

    Combine this with the fact that an un-OCed Celeron runs with only a 66 MHz bus, compared with 100 MHz for a P2. Even though the Celeron needs more memory bandwidth than a P2, it gets less.

    Now stick two of these bandwidth-hungry chips on the same board accessing the same 66 MHz RAM...

    I suspect it would not be worth it unless you used 300As at 450+ (100+ MHz FSB).

    Does anyone have performance numbers for un-overclocked Celeron SMP?

  2. Very risky by heroine · · Score: 3

    The idea of using Celerons only works if you can overclock them. It may go well for hacks and tinkers, but for the heavy video and I/O, a 66Mhz bus frequency is unacceptable. The chances of overclocking single celerons to a 100Mhz bus is 75%. For both processors in a dual processor system, the success drops to 56%. Also since people are much less willing to report failure publicly, the percentages may even be lower in real life. You won't see anyone post a failed overclock on slashdot.