Messages in this thread | | | Date | Thu, 1 Jun 2017 14:17:21 +0200 | From | Peter Zijlstra <> | Subject | Re: [RFC PATCH 00/10] x86: undwarf unwinder |
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On Thu, Jun 01, 2017 at 06:58:20AM -0500, Josh Poimboeuf wrote: > > Being able to generate more optimal code in the hottest code paths of the kernel > > is the _real_, primary upstream kernel benefit of a different debuginfo method - > > which has to be weighed against the pain of introducing a new unwinder. But this > > submission does not talk about that aspect at all, which should be fixed I think. > > Actually I devoted an entire one-sentence paragraph to performance in > the documentation: > > The simpler debuginfo format also enables the unwinder to be relatively > fast, which is important for perf and lockdep. > > But I'll try to highlight that a little more.
That's relative to a DWARF unwinder. It doesn't appear to be possible to get anywhere near a frame-pointer unwinder due to having to do this log(n) lookup for every single frame.
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