Re: [patch 04/17] Add pagetable accessors to pack and unpack pagetable entries

Rusty Russell
2007-04-04T23:00:01Z

On Wed, 2007-04-04 at 17:56 +0200, Andi Kleen wrote:
> On Wednesday 04 April 2007 17:45:44 Jeremy Fitzhardinge wrote:
> > Andi Kleen wrote:
> > > Why is there a difference for null syscall? I had assumed we patched all the
> > > fast path cases relevant there. Do you have an idea where it comes from?
> >
> > Sure. There's indirect calls for things like sti/cli/iret. It goes
> > back to native speed when you patch the real instructions inline.
>
> I was talking about the patched case. It seemed to be a little slower
> too, but in theory it shouldn't have been, no?

You'll still have the damage inflicted on gcc's optimizer, though.

Rusty.