On Fri, May 31, 2013 at 03:02:29PM +0200, Stephane Eranian wrote: > Hi, > > So looked at this patch again. There is nothing wrong with the code. > But there is something bothering me with the usage model. I think > the choice of having pebs->ip for precise=1 or pebs->real_ip for > precise=2 is too restrictive. > > There are situations where you want BOTH the real_ip AND the > off-by-one ip. This is when you're sampling call branches. > The real_ip gives you the call site, the off-by-one gives you > the target of the branch. This is very handy because you do > not need to use the LBR to get this, unlike with SandyBridge.
It's also useful for TSX: critical section versus abort point inside transaction. > So we need to find an extension or a way to return both IPs > without invoking LBR. Easiest would be to add another > PERF_SAMPLE_*. > > Any better idea? For TSX I just use two different events. It works. I'm not disagreeing with it, but I think it's an orthogonal issue to my patchkit. Adding a new SAMPLE type seems reasonable to me. -Andi -- 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/