Messages in this thread | | | Date | Mon, 02 Feb 2015 14:19:35 -0500 | From | Rik van Riel <> | Subject | Re: [PATCH 5/6] x86,fpu: also check fpu_lazy_restore when use_eager_fpu |
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On 02/02/2015 01:55 PM, Oleg Nesterov wrote: > On 02/02, riel@redhat.com wrote: >> >> From: Rik van Riel <riel@redhat.com> >> >> With Oleg's patch "x86, fpu: don't abuse FPU in kernel threads >> if use_eager_fpu()", kernel threads no longer have an FPU state >> even on systems with use_eager_fpu() >> >> That in turn means that a task may still have its FPU state >> loaded in the FPU registers, if the task only got interrupted by >> kernel threads from when it went to sleep, to when it woke up >> again. >> >> In that case, there is no need to restore the FPU state for this >> task, since it is still in the registers. >> >> The kernel can simply use the same logic to determine this as is >> used for !use_eager_fpu() systems. > > Yes, agreed, I was going to do this too. > > And in fact this change make sense even without "don't abuse FPU in > kernel threads", I think. > > But in theory it depends on another change, "__kernel_fpu_begin() > should clear fpu_owner_task even if use_eager_fpu()". > > And that series was ignored ;) > > I think this patch is fine.
Ingo,
does the FPU code have a sub-maintainer, or should all the FPU patches go straight through you?
Would it be better for you if FPU patches came through a git tree you could just pull?
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