Re: [RFC PATCH] x86, fpu: Use eagerfpu by default on all CPUs

From: Oleg Nesterov
Date: Mon Feb 23 2015 - 13:42:50 EST

On 02/23, Rik van Riel wrote:
> Hash: SHA1
> On 02/23/2015 10:11 AM, Borislav Petkov wrote:
> > On Mon, Feb 23, 2015 at 03:59:29PM +0100, Oleg Nesterov wrote:
> >> Well, but if we want this change then perhaps we should simply
> >> change the default value? This way "AUTO" still can work.
> >
> > Yeah, sure, let's do some measurements first, to see whether this
> > is even worth it.
> >
> > Btw, Mel pointed me at some cleanups he did a while ago in that
> > area too:
> >
> > If you guys could take a look, that would be awesome :)
> I don't think any of those changes would survive the
> "defer FPU loading to do_notify_resume" patch series.

Agreed, at least

+static inline void switch_eagerfpu_prepare(struct task_struct *old, struct task_struct *new, int cpu,
+ fpu_switch_t *fpu)
+ fpu->preload = tsk_used_math(new);

doesn't look right if we change the rules.

OTOH, perhaps it makes sense to redo these cleanups later.


To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at