Messages in this thread | ![/](/images/icornerl.gif) | | From | "Liang, Kan" <> | Subject | RE: [PATCH 1/1] perf,tools: add time out to force stop endless mmap processing | Date | Sat, 13 Jun 2015 14:59:56 +0000 |
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> > > The maps information is not critical for sampling. > > But is for correlating the addresses in those samples.
We still have the maps information for other threads in system. Only part of the information for some thread is lost.
> > > > > If task_diag does not solve this problem, I think we still need a time > > out to force stop endless mmap processing. It's the simplest working > > solution so far. > > I disagree with the timeout. For example an overloaded system where > perf is not getting scheduled could trigger the same.
It's not a perfect solution for all tools. But a working solution for perf. Without timeout, we get nothing from perf top/record. With timeout, we can do sampling. We can correlate the addresses in most samples. It's better than nothing.
> > Also, in the spirit of perf if you are going to drop information you need to > generate an event that says information was lost and have the analysis > tools show a message that information was lost. You can't simply bail out > and have "[unknown]" shown for symbols / dsos. I get tons of user > comments about perf showing callchains properly; the proposed patch just > adds to that confusion.
Currently, it will print a warning in perf top/record. I think I can do more and print warning in perf_session__warn_about_errors as Arnaldo suggested.
Thanks, Kan
> > David
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