| Date | Wed, 25 Nov 2020 14:45:37 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH -tip 31/32] sched: Add a coresched command line option |
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On Tue, Nov 17, 2020 at 06:20:01PM -0500, Joel Fernandes (Google) wrote: > Some hardware such as certain AMD variants don't have cross-HT MDS/L1TF > issues. Detect this and don't enable core scheduling as it can > needlessly slow those device down. > > However, some users may want core scheduling even if the hardware is > secure. To support them, add a coresched= option which defaults to > 'secure' and can be overridden to 'on' if the user wants to enable > coresched even if the HW is not vulnerable. 'off' would disable > core scheduling in any case.
This is all sorts of wrong, and the reason is because you hard-coded that stupid policy.
Core scheduling should always be available on SMT (provided you did that CONFIG_ thing). Even on AMD systems RT tasks might want to claim the core exclusively.
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