[PATCH 0/3] x86, fpu: kernel_fpu_begin/end initial cleanups/fix

Oleg Nesterov
2015-01-15T19:20:26Z

Add cc's.

On 01/11, riel@redhat.com wrote:
>
> Currently the kernel will always load the FPU context, even
> when switching to a kernel thread, or to an idle thread. In
> the case of a task on a KVM VCPU going idle for a bit, and
> waking up again later, this creates a vastly inefficient
> chain of FPU context saves & loads:

I assume you will send v2.

Let me send initial kernel_fpu_begin/end cleanups, I believe they make
sense anyway and won't conflict with your changes.

This is actually resend, I sent more patches some time ago but they were
ignored.

Note that (I hope) we can do more changes on top of this series, in
particular:

- remove all checks from irq_fpu_usable() except in_kernel_fpu

- do not abuse FPU in kernel threads, this makes sense even if
use_eager_fpu(), and with or without the changes you proposed.

Please review.

Oleg.