Re: [Patch] mm tracepoints

Larry Woodman
2009-03-06T19:19:23Z

On Fri, 2009-03-06 at 18:10 +0100, Ingo Molnar wrote:
> * Larry Woodman <lwoodman@redhat.com> wrote:
>
> > > Would that be useless or controversial? We know from
> > > vma->mapping which inode it maps to. Knowing which file is
> > > faulting in can be useful - especially when addresses are a
> > > moving target such as under PIE or with dlopen(), etc.
> > >
> > > Ingo
> >
> > Attached is the updated patch that applies and builds
> > correctly (sorry I missed the lockdep tracepoints that were
> > added at the last minute). [...]
>
> Looks pretty good and useful to me. I've Cc:-ed more mm folks,
> it would be nice to hear their opinion about these tracepoints.
>
> Andrew, Nick, Peter, what do you think?
>
> About the motivation of these tracepoints: i suspect these
> tracepoints reflect your years-long experience in dealing with
> various MM regressions in the enterprise space and these
> tracepoints would help understand such regressions
> faster/easier?

Exactly, and without running some "debug enhanced kernel".

>
> > [...] As far as the filename:offset is concerned I am working
> > on that. Its not as simple as it looks because we have to
> > follow a variable list of structs that can be null terminated
> > several places along the way.
>
> It's definitely not simple! I dont think it should be in this
> base patch at all - it should be an add-on.
>
> Ingo