Re: i386 PDA patches use of %gs

[Ingo Molnar <mingo@elte.hu>]

* Jeremy Fitzhardinge <jeremy@goop.org> wrote:

> Ingo Molnar wrote:
> > i'd not even use glibc's %gs but set up two separate selectors. 
> > (that's a more controlled experiment - someone might run a non-TLS 
> > glibc, etc.)
> >   
> 
> Well, in that case they probably don't care whether the kernel uses 
> %fs or %gs ;)
> 
> But either way, this doesn't have much bearing on Eric's test; we'd be 
> only talking about a few ns per kernel exit, rather than 5% for 
> read/write.

if the timings are different then it very much has bearing on the 
argument that i made against the current i386 PDA patchset, that mixed 
use segments are suboptimal.

So i'm NAK-ing the i386 PDA patchset until this has been properly 
measured (and fixed if needed).

	Ingo