A hotspot patch for stack profiling (frame pointer)
aph at redhat.com
Tue Dec 9 09:39:53 UTC 2014
On 08/12/14 22:19, Brendan Gregg wrote:
> It's a good idea, but I'm not sure the DWARF unwind approach is
> suitable for dynamic JIT. I'm usually sampling at 99 Hertz. With
> inlined symbols, just the perf.map file can become 10s of Mbytes, and
> I assume the DWARF info would be similar. So the file would need to be
> in a consistent state so that perf can begin reading it anytime, and
> do stack walking based on what it reads, while at the same time
> symbols may be compiled anytime and the map file would need to change.
Valgrind has a nice solution to this: a high-speed DWARF unwinder
cache which converts the unwind info into an internal form.
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