Re: [PATCH 4/5] kmemtrace: SLUB hooks.

Matt Mackall
2008-08-13T02:09:59Z

On Tue, 2008-08-12 at 18:29 +0300, Eduard - Gabriel Munteanu wrote:
> On Mon, Aug 11, 2008 at 05:22:37PM +0300, Pekka Enberg wrote:
> > On Mon, 2008-08-11 at 09:21 -0500, Christoph Lameter wrote:
> > > Pekka Enberg wrote:
> > >
> > > > The function call is supposed to go away when we convert kmemtrace to
> > > > use Mathieu's markers but I suppose even then we have a problem with
> > > > inlining?
> > >
> > > The function calls are overwritten with NOPs? Or how does that work?
> >
> > I have no idea. Mathieu, Eduard?
>
> Yes, the code is patched at runtime. But AFAIK markers already provide
> this stuff (called "immediate values"). Mathieu's tracepoints also do
> it. But it's not available on all arches. x86 and x86-64 work as far as
> I remember.

Did we ever see size(1) numbers for kernels with and without this
support? I'm still a bit worried about adding branches to such a popular
inline. Simply multiplying the branch test by the number of locations is
pretty substantial, never mind the unlikely part of the branch.

--
Mathematics is the supreme nostalgia of our time.