| Date | Tue, 13 Jan 2015 18:58:04 +0100 | From | Oleg Nesterov <> | Subject | Re: [RFC PATCH 04/11] x86,fpu: defer FPU restore until return to userspace |
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On 01/11, riel@redhat.com wrote: > > Defer restoring the FPU state, if so desired, until the task returns to > userspace.
And yet another concern ;) Although I feel that I am totally confused and probably wrong.
> --- a/arch/x86/include/asm/fpu-internal.h > +++ b/arch/x86/include/asm/fpu-internal.h > @@ -382,6 +382,7 @@ static inline void drop_init_fpu(struct task_struct *tsk) > else > fxrstor_checking(&init_xstate_buf->i387); > } > + clear_thread_flag(TIF_LOAD_FPU); > }
OK, but shouldn't (say) restore_user_xstate() clear TIF_LOAD_FPU too? Otherwise, can't switch_fpu_finish() restore the wrong context later?
Or. Perhaps switch_fpu_finish() should do nothing if fpu.has_fpu == T, I dunno.
Oleg.
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