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> They must be applications with extremely bad design causing super low cache hits Yep, this is exactly the case - also, on systems that are busy and context-s
by erulabs 5y ago
> They must be applications with extremely bad design causing super low cache hits
Yep, this is exactly the case - also, on systems that are busy and context-switching often and thus flushing their cpu caches more frequently. Combine the two, busy systems running loads of un-optimized code, and boom, you have described how most computers run in the real world. This is why "synthetic" benchmarks, which are well designed code running on quiet machines more or less match up to CPU Frequency exclusively.
I don't really have any good charts to show you, but you might checkout an old review of the processor I mentioned as having one of the first on-die memory controllers: https://techreport.com/review/5655/amds-opteron-146-processor/ https://techreport.com/review/5655/amds-opteron-146-processo...
The AMD Opteron 240 1.4GHz keeps up with chips close to 2x it's frequency - and the memory access times are close to 1/2 as costly (ie: almost all the performance gain from 2x frequency is made up by 1/2 memory access time) - this makes sense, but remember these are well optimized applications (POV-Ray and Lightwave were extremely synthetic). In the real world, opening 10 misc windows applications from 2003, the K8 (particularly when overclocked) was a _beast_.
- sroussey 5y agoThis is why you dedicate entire machines to the same kind of load. All application code or all database. There was a moment where people tried to integrate—which was indeed faster but only for very limited use cases.
- mda 5y agoWell, Opteron is an ancient processor, I don't think we can make any conclusion based on that. Today's server processors has enormous caches compared to Opteron. Honestly in cases you mention, badly designed processes killing the Cpu, I fail to see how faster ram makes a huge difference.
- erulabs 5y agoI mean - the people who designed Gravaton 3 seem to agree with my premise, so at least that’s some validation. Alternatively, do some CPU profiling with your workstation - a massive amount of time is simple waiting for memory returns.