On Mon, Oct 26, 2009 at 6:44 AM, Randy Bias <
randyb@cloudscaling.com> wrote:
This is hard. CPU 'clock cycles' are not equivalent. This is why Amazon uses a very specific processor and year to create their ECU. The 2007 1.2Ghz processors all road on 800Mhz FSBs, which limited the amount of memory bandwidth (among other things). Whereas modern CPUs and the much better/faster busses of today mean that you can feed the CPU much faster.
Now this is relevant because there was some contention (for reasons unknown) over the inclusion of quantitative measurements of performance characteristics such as memory bandwidth. Surely if some providers (or individual nodes) are using slow RAM, buses, storage devices, etc. then as a consumer I should be able to find out about it and/or set parameters on it? Conversely if I have an application that requires ridiculously fast storage (say, SSD) then I should be able to request this based on raw performance figures (the "what" rather than the "how").
My point isn't that you shouldn't do it, it's simply that it's tricky.
If I had to make a recommendation it would be to baseline off of the Amazon ECU.
Interesting idea but surely that too is a moving target? Would it not also favour Intel over AMD (or vice versa)? Having a standard unit to measure against is an interesting idea, like the standard kilogram, and perhaps it's something that could be built from commodity components.
Sam
On Oct 25, 2009, at 7:56 PM, Sam Johnston wrote:
I think you've touched on an interesting point there which ties in to the "need" for a universal compute unit
Randy Bias, Founder & Cloud Strategist, Cloudscaling
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