Messages in this thread | | | From | Andi Kleen <> | Subject | Re: [PATCH v4 0/3] Compile-time stack frame pointer validation | Date | Tue, 26 May 2015 16:06:28 -0700 |
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Ingo Molnar <mingo@kernel.org> writes: > > Especially on modern x86 CPUs with stack engines (latest Intel and AMD > CPUs) that keeps ESP updates out of the later stages of execution > pipelines, going from RBP framepointers to direct ESP use is > beneficial to performance and compresses I$ footprint as well:
Note that Atom doesn't have this stack engine, so you'll likely see even more difference there.
> So the performance advantages of not doing framepointers is not > something we can ignore IMHO:
Agreed.
> but obviously performance isn't > everything - so if stack unwinding is unrobust, then we need and > want frame pointers.
It wasn't that bad in the old days with the approx stack traces. In fact I bet it would be possible to write an automated tool that weeds out many (most?) false positives automatically with a static compile-time callgraph.
It would be good to at least make it easier building without them again. Currently it's very difficult because a lot of subsystems force select frame pointers.
-Andi
-- ak@linux.intel.com -- Speaking for myself only
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