[PATCH] D53562: [ARM] Use the Cortex-A57 sched model for Cortex-A72

Florian Hahn via Phabricator via llvm-commits llvm-commits at lists.llvm.org
Wed Oct 24 04:57:05 PDT 2018


fhahn added a comment.

In https://reviews.llvm.org/D53562#1273812, @samparker wrote:

> Hey Florian,
>
> It was brought to my attention that the scheduler still wasn't enabled because of the missing feature. I've now added this and the geomean improvement is 2.23%. I will shortly add a couple of tests too.


So yes, to enable the machine scheduler for a core on ARM, FeatureUseMISched is required. I think it is worth splitting using the Cortex-A57 model and enabling the machine scheduler for Cortex-A72. The A57 model should be more accurate for A72 than no model.

For changing to using the MachineScheduler, the last time I looked at it (about a year ago), I remember seeing some relatively big regressions on some benchmarks, so we might want to be a bit more cautious there, as there might be potential to tweak the scheduling heuristics for ARM. Also, I think it would be good to have numbers for a large set of benchmarks (test-suite + commercial ones)


https://reviews.llvm.org/D53562





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