Thanks! At this point, that same benchmark has about 1 empty stack trace per 300 samples, which should be good enough.
Vincent At Mon, 12 Aug 2013 17:25:38 -0600, Matthew Flatt wrote: > > I've pushed a repair for the main problem on x86_64 Linux (and other > platforms that use DWARF-based stack unwind). > > A related symptom I had noticed was that building without gcc > optimization used disabled stack traces; that's now fixed. > > There are still ways to end up with an empty stack trace, but it should > happen much less often. > > At Wed, 07 Aug 2013 17:49:57 -0400, Vincent St-Amour wrote: > > > > I'm profiling one of the contract benchmarks[1], and I noticed that > > sometimes (about 10 out of 300 samples), `continuation-mark-set->context' > > would return an empty stack trace. This number is cut down by about half > > if I disable the JIT. These samples seem to be spread out throughout > > execution (i.e. not all at the beginning or at the end). > > > > I think this may be a regression. At least I've never observed that > > before (and since this causes the contract profiler to error (a bug > > which I'll fix), I probably would have noticed). > > > > This may be a problem because it would reduce the precision of the > > profiler by undercounting what actually was on the stack while these > > empty samples are taken. > > > > > > To observe this, clone the contract benchmarks repository[1], then run > > the attached version of render-guide.rkt inside that directory. To count > > the number of empty stack traces, apply the attached patch to the > > profiler. > > > > > > Vincent > > > > > > [1] https://github.com/stamourv/contract-benchmarks > > > > > > > > ------------------------------------------------------------------------------ > > [application/octet-stream "render-guide.rkt"] [~/Desktop & open] [~/Temp & > > open] > > > > ------------------------------------------------------------------------------ > > [application/octet-stream > > "0001-Have-profiler-print-number-of-empty-stack-traces.patch"] [~/Desktop & > > open] [~/Temp & open] > > _________________________ > > Racket Developers list: > > http://lists.racket-lang.org/dev _________________________ Racket Developers list: http://lists.racket-lang.org/dev
