lkml.org 
[lkml]   [2009]   [Nov]   [8]   [last100]   RSS Feed
Views: [more markup]  [less markup]  [headers]  [forward] 
 
Messages in this thread
/
DateSun, 8 Nov 2009 17:47:06 +0100
FromIngo Molnar <>
SubjectRe: [PATCH 02/11] Add "handle page fault" PV helper.

* H. Peter Anvin <hpa@zytor.com> wrote:

> On 11/08/2009 04:51 AM, Ingo Molnar wrote:
> >
> > * Avi Kivity <avi@redhat.com> wrote:
> >
> >> On 11/08/2009 01:36 PM, Ingo Molnar wrote:
> >>>> Three existing callbacks are: kmemcheck, mmiotrace, notifier. Two
> >>>> of them kmemcheck, mmiotrace are enabled only for debugging, should
> >>>> not be performance concern. And notifier call sites (two of them)
> >>>> are deliberately, as explained by comment, not at the function entry,
> >>>> so can't be unified with others. (And kmemcheck also has two different
> >>>> call site BTW)
> >>>
> >>> We want mmiotrace to be generic distro capable so the overhead when
> >>> the hook is not used is of concern.
> >>
> >> Maybe we should generalize paravirt-ops patching in case if (x) f() is
> >> deemed too expensive.
> >
> > Yes, that's a nice idea. We have quite a number of 'conditional
> > callbacks' in various critical paths that could be made lighter via such
> > a technique.
> >
> > It would also free new callbacks from the 'it increases overhead
> > even if unused' criticism and made it easier to add them.
>
> There are a number of other things were we permanently bind to a
> single instance of something, too. Optimizing those away would be
> nice. Consider memcpy(), where we may want to have different
> implementations for different processors.

yeah.

Ingo
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2009-11-08 17:49    [W:0.202 / U:0.120 seconds]
©2003-2009 Jasper Spaans