Re: [PATCH] perf tools: Add dedicated unwind addr_space member into thread struct

[Milian Wolff <milian.wolff@kdab.com>]

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On Mittwoch, 6. April 2016 17:46:57 CEST Jiri Olsa wrote:
> On Tue, Apr 05, 2016 at 10:35:24AM +0200, Jiri Olsa wrote:
> > On Mon, Apr 04, 2016 at 11:17:11PM +0200, Milian Wolff wrote:
> > 
> > SNIP
> > 
> > >             7f688a5ef0c4 usleep (/usr/lib/libc-2.23.so)
> > >             5582244227cd main (/tmp/ex_sleep)
> > >   
> > >   1001.702 ( 0.059 ms): ex_sleep/4390 nanosleep(rqtp: 0x7ffe4d16eec0
> > > 
> > > ) = 0
> > > 
> > >                   20379e syscall_slow_exit_work ([kernel.kallsyms])
> > >                   203bc4 syscall_return_slowpath ([kernel.kallsyms])
> > >                   797248 int_ret_from_sys_call ([kernel.kallsyms])
> > >             
> > >             7f688a5c5600 __nanosleep (/usr/lib/libc-2.23.so)
> > >             7f688a5ef0c4 usleep (/usr/lib/libc-2.23.so)
> > >             5582244227d7 main (/tmp/ex_sleep)
> > > 
> > > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > > 
> > > Is there a way to increase the event buffer or something like that to
> > > not lose events when the costly dwarf unwinding happens for the first
> > > time? Consecutive unwinding is cached by libunwind and much faster.
> > 
> > not sure about perf trace, but there's -m option available for perf record
> > that allows you to increase the buffer size
> > 
> > > Alternatively, I could try to unwind in the `sys_enter`, but then I'd
> > > need to buffer the output to print the trace after the duration line...
> > > 
> > > How would you guys handle this situation?
> > > 
> > > Also, Jiri, Arnaldo - what would be your suggestion on how to handle the
> > > `thread::priv` situation - I doubt my naive `priv2` approach is
> > > acceptable.
> > 
> > yea, I think one priv is more than enough ;-)
> > 
> > I think we want to move the the unwinder usage of this field into separate
> > field
> need to run test over this, but will try to post it this week
> let me know if this solution would work for you

Yes, works for me, thanks a lot!

Feel free to add

    Tested-by: Milian Wolff <milian.wolff@kdab.com>

-- 
Milian Wolff | milian.wolff@kdab.com | Software Engineer
KDAB (Deutschland) GmbH&Co KG, a KDAB Group company
Tel: +49-30-521325470
KDAB - The Qt Experts

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