Re: [PATCH] tracing/branch-tracer: PROFILE_BRANCHES_PER_CPU must depend on SMP

Frederic Weisbecker
2009-06-06T14:56:36Z

On Sat, Jun 06, 2009 at 10:42:29AM -0400, Steven Rostedt wrote:
>
> On Sat, 6 Jun 2009, Frederic Weisbecker wrote:
> >
> > [ Impact: fix a build failure with the branch tracer ]
> >
> > Reported-by: Ingo Molnar <mingo@elte.hu>
> > Cc: Steven Rostedt <rostedt@goodmis.org>
> > Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
> > ---
> > kernel/trace/Kconfig | 2 +-
> > 1 files changed, 1 insertions(+), 1 deletions(-)
> >
> > diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
> > index 309a264..0efbcc5 100644
> > --- a/kernel/trace/Kconfig
> > +++ b/kernel/trace/Kconfig
> > @@ -285,7 +285,7 @@ endchoice
> >
> > config PROFILE_BRANCHES_PER_CPU
> > bool "Profile branches on a per cpu basis"
> > - depends on PROFILE_ALL_BRANCHES
> > + depends on PROFILE_ALL_BRANCHES && SMP
>
> You just wasted two minutes of my time!
>
> I was just about to send out the same patch, but you beat me to it. ;-)
>
> Acked-by: Steven Rostedt <rostedt@goodmis.org>

We really need a mutex... ;-)

Frederic.

>
> -- Steve
>
>
> > help
> > When profiling all branches, the system can take a big cache line
> > bouncing hit. On boxes with lots of CPUs, this can slow the system
> > --
> > 1.6.2.3
> >
> >