Messages in this thread | | | Date | Mon, 19 Oct 2015 10:08:52 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH 1/1] perf/x86: Fix time_shift in perf_event_mmap_page |
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* Adrian Hunter <adrian.hunter@intel.com> wrote:
> Commit b20112edeadf ("perf/x86: Improve accuracy of perf/sched clock") > allowed the time_shift value in perf_event_mmap_page to be as much > as 32. Unfortunately the documented algorithms for using time_shift > have it shifting an integer, whereas to work correctly with the value > 32, the type must be u64. > > Fix by limiting the shift to 31 and adjusting the multiplier accordingly. > > Also update the documentation of perf_event_mmap_page so that new code > based on it will be more future-proof. > > Fixes: b20112edeadf ("perf/x86: Improve accuracy of perf/sched clock") > Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Would be nice to point out via what symptoms the code misbehaves and how users notice.
Thanks,
Ingo
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