Messages in this thread | | | Date | Mon, 8 Apr 2019 19:08:49 +0200 (CEST) | From | Thomas Gleixner <> | Subject | Re: [PATCH v9 00/27] x86: load FPU registers on return to userland |
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On Wed, 3 Apr 2019, Sebastian Andrzej Siewior wrote:
> This is a refurbished series originally started by by Rik van Riel. The > goal is load the FPU registers on return to userland and not on every > context switch. By this optimisation we can: > - avoid loading the registers if the task stays in kernel and does > not return to userland > - make kernel_fpu_begin() cheaper: it only saves the registers on the > first invocation. The second invocation does not need save them again. > > To access the FPU registers in kernel we need: > - disable preemption to avoid that the scheduler switches tasks. By > doing so it would set TIF_NEED_FPU_LOAD and the FPU registers would be > not valid. > - disable BH because the softirq might use kernel_fpu_begin() and then > set TIF_NEED_FPU_LOAD instead loading the FPU registers on completion.
So aside of that one hunk in 24/27 which is either wrong or needs some information in the changelog I couldn't find anything disturbing.
With that addressed:
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
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