Closed Bug 1374248 Opened 5 years ago Closed 5 years ago
LUL: remove stack scanning
LUL, which currently provides native unwinding for the Gecko profiler on 32- and 64-bit x86 Linux, has the ability to recover stack frames heuristically using stack scanning. Stack scanning was added in an attempt to have functional parity with the Breakpad unwinder, which preceded LUL in this role. However, the profiler calls LUL with a parameter which limits the number of scan-recovered frames to zero -- in other words it is disabled. Previous experimentation with stack scanning shows that it often recovers incorrect frames and so throws unwinding off the trail completely. It seems more suited to an unwind-after-crash scenario -- where we want to get as much information as we can, accepting the risk that it might be wrong -- and less suited to a profiling scenario, where we prefer to have incomplete stacks rather than incorrect ones. So this bug proposes to remove stack scanning from LUL. Given that it's not currently used, there will be zero visible functional changes.
Assignee: nobody → jseward
Attachment #8879433 - Flags: review?(n.nethercote)
Attachment #8879433 - Flags: review?(n.nethercote) → review+
Pushed by firstname.lastname@example.org: https://hg.mozilla.org/integration/mozilla-inbound/rev/5860160aa255 LUL: remove stack scanning. r=njn.
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