This is great! Thanks for working on it! Can the new library be used independently outside of SPS? For hang detection (bug 909974) we'd like to have the ability to unwind the hung thread's stack, and this library would be perfect for that.
Cheers, Jim On 12/19/13 2:04 PM, Julian Seward wrote: > > Here's a status update. > > Recap: I proposed to create a new library to do fast in process > CFI and EXIDX based stack unwinding, so as to be able to profile > on tablets and phones with less overhead than using Breakpad. > > The library now exists. Tracking bug is 938157. It does > CFI unwinding on x86_64-linux and arm-android, EXIDX on arm-android, > and stack scanning (as a last resort) on both. Initial > integration with SPS has been completed and it produces plausible > profiles at least on x86_64-linux. > > Compared with the best Breakpad based schemes, this library gives > easily a factor of 10 cost reduction for CFI unwinding. My best > attempts with Breakpad achieved a cost of about 6600 insns/frame > on x86_64-linux. The new library comes in at around 470 insns/frame, > without much attempt at optimisation. > > It also facilitates implementation of the the kind of space-saving > techniques documented in > https://blog.mozilla.org/jseward/2013/09/03/how-compactly-can-cfiexidx-stack-unwinding-info-be-represented/ > > J > > _______________________________________________ > dev-platform mailing list > dev-platform@lists.mozilla.org > https://lists.mozilla.org/listinfo/dev-platform > _______________________________________________ dev-platform mailing list dev-platform@lists.mozilla.org https://lists.mozilla.org/listinfo/dev-platform
