Re:Intel Discloses Lakefield CPUs Specifications
by notriddle on Wednesday June 10, 2020 @08:30PM
(#23483858)
I'm not sure how this is different from the existing big.LITTLE "lottery", between being scheduled on a CPU with a deep speculative pipeline and a high clock rate or a CPU with less.
If the microcoded vector ops cause your code to run slow, then you will be consuming lots of CPU time, and should be migrated to the big core anyway, right?
Re:Intel Discloses Lakefield CPUs Specifications
by wmf on Wednesday June 10, 2020 @04:02PM
(#23481400)
So, performance oriented code will pin its performance-critical threads to the fast CPU. Now, the question is: what code won’t try to claim the faster CPU
Do apps have CCX pinning logic for Ryzen? No? Why would they add it for an Intel processor that probably won't even be sold in volume.
I don’t think users would be happy if it were a lottery whether their code runs slow, using microcode instructions, or fast, on the better CPU, especially given that, I guess, the difference in instruction set is for vector instructions (because adding those is what’s makes a CPU big nowadays)
So, performance oriented code will pin its performance-critical threads to the fast CPU. Now, the question is: what code won’t try to claim the faster CPU, given that benchmarks typically run programs while there is no contention from other programs?