On Tue, Oct 07, 2014 at 03:00:43AM +0000, Liang, Kan wrote: > > > > > > On Wed, Sep 10, 2014 at 10:09:11AM -0400, [email protected] wrote: > > > From: Kan Liang <[email protected]> > > > > > > If a task specific event wants user space callchain but does not want > > > branch stack sampling, enable the LBR call stack facility implicitly. > > > The LBR call stack facility can help perf to get user space callchain > > > in case of there is no frame pointer. > > > > > > Note: this feature only affects how to get user callchain. The kernel > > > callchain is always got by frame pointers. > > > > Yeah, don't like this either. Suppose you have sane userspace (with > > framepointers enabled) then you're now loosing the better option. > > FP is the first option. This patch tries to enable LBR call stack facility > implicitly. > Only when FP disabled or failed, we try to use LBR call stack. > Please refer to the previous patch https://lkml.org/lkml/2014/9/10/376
Still makes for an entirely unpredictable situation. That way you never quite know where your data came from. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
