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Date: Fri, 14 Jul 2017 10:29:02 +0200
From: Ingo Molnar <mingo@kernel.org>
To: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
        Andres Freund <andres@anarazel.de>, x86@kernel.org,
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        Jiri Olsa <jolsa@redhat.com>,
        Arnaldo Carvalho de Melo <acme@infradead.org>,
        Namhyung Kim <namhyung@kernel.org>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>
Subject: Re: [PATCH v3 00/10] x86: ORC unwinder (previously undwarf)
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* Josh Poimboeuf <jpoimboe@redhat.com> wrote:

> For user space stack unwinding, the kernel could emulate what the kernel
> 'guess' unwinder does by scanning the user space stack and returning all
> the text addresses it finds.

User-space stacks tend to be much larger than kernel stacks, the cost of doing 
such a full scan on every PMI would kill a lot of profiling workloads.

Thanks,

	Ingo