On Fri, Feb 27, 2015 at 08:58:29AM +0100, Peter Zijlstra wrote: > On Mon, Feb 23, 2015 at 09:44:48AM -0800, Andi Kleen wrote: > > On Mon, Feb 23, 2015 at 05:49:57PM +0100, Peter Zijlstra wrote: > > > On Mon, Feb 23, 2015 at 03:43:41AM +0000, kan.li...@intel.com wrote: > > > > From: Kan Liang <kan.li...@intel.com> > > > > > > > > Haswell has a new feature that utilizes the existing Last Branch Record > > > > facility to record call chains. It has been implemented in perf. The > > > > call chains information is saved during perf event context. > > > > > > > > This patch exposes a /proc/<pid>/lbr_stack file that shows the saved LBR > > > > call chain information. > > > > > > But why? I mean, this thing is only useful if you have a concurrently > > > running perf record that selects the LBR-stack stuff. > > > > > > And if you have that, you might as well look at its output instead. Why > > > add this unconditional proc file that doesn't function on its own? > > > > perf record doesn't show where you're currently blocked. > > Of course it does; look at perf inject -s.
Trace points don't support the LBR stack. -Andi -- a...@linux.intel.com -- Speaking for myself only -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
