Re: [RFC PATCH 3/3] ARM: vfp: Use cpu pm notifiers to save vfpstate

[Russell King - ARM Linux]

On Fri, Feb 11, 2011 at 12:12:25PM +0000, Catalin Marinas wrote:
> On SMP systems, we save the VFP at every context switch to deal with the
> thread migration (though I have a plan to make this lazily on SMP as
> well).

I'm not sure it's worth the complexity.  You'd have to do an IPI to the
old CPU to provoke it to save the context from its VFP unit.  You'd have
to do that in some kind of atomic way as the old CPU may be in the middle
of already saving it.  You're also going to have to add locking to the
last_VFP_context[] array as other CPUs will be accessing non-local
entries, and that means doing locking in assembly.  Yuck.

No, let's not go there.  Stick with what we currently have which works
well.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/