On Wed, Feb 26, 2014 at 10:55 AM, Andi Kleen <a...@firstfloor.org> wrote: >> I'm suggesting a perf event option, just like the way that PEBS works. > > Right now it's a somewhat experimental feature and just having > the sysctl is fine. If it turns out that is what everyone uses > such an option could be still added later.
I'm a bit worried that the syscall will be stuck as ABI forever, though. Its presence will make adding a different configuration mechanism awkward. > > I suspect most people would still use FP if they can, just use > the LBRs if that doesn't work. I wonder if anyone who uses perf for userspace profiling *ever* uses FP and gets away with it. There's precious little userspace software compiled with frame pointers these days on most architectures. I have a concrete reason for this question: it would be nice to compile the vDSO with frame pointers off. IIRC there would be a significant performance gain, and I think the only thing that would break is perf. But it looks like perf will have nice elfutils unwind support in 3.15, and if FP support is useless anyway... --Andy -- 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/
