From: Peter Zijlstra <peterz@infradead.org>
To: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: "Stephane Eranian" <eranian@google.com>,
"David Ahern" <dsahern@gmail.com>,
"Milian Wolff" <milian.wolff@kdab.com>,
"Frédéric Weisbecker" <fweisbec@gmail.com>,
"Ingo Molnar" <mingo@kernel.org>,
"Namhyung Kim" <namhyung@kernel.org>,
"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>
Subject: Re: LBR callchains from tracepoints
Date: Tue, 26 Apr 2016 18:38:28 +0200 [thread overview]
Message-ID: <20160426163828.GA3448@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <20160426012431.GE16708@kernel.org>
On Mon, Apr 25, 2016 at 10:24:31PM -0300, Arnaldo Carvalho de Melo wrote:
> Em Mon, Apr 25, 2016 at 10:03:58PM -0300, Arnaldo Carvalho de Melo escreveu:
> > I now need to continue investigation why this doesn't seem to work from
> > tracepoints...
>
> Bummer, the changeset (at the end of this message) hasn't any
> explanation, is this really impossible? I.e. LBR callstacks from
> tracepoints? Even if we set perf_event_attr.exclude_callchain_kernel?
Could maybe be done, but its tricky to implement as the LBR is managed
by the hardware PMU and tracepoints are a software PMU, so we need to
then somehow frob with cross-pmu resources, in a very arch specific way.
And programmability of the hardware PMU will then depend on events
outside of it.
All rather icky.
next prev parent reply other threads:[~2016-04-26 16:38 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-19 0:07 Missing stack symbols with perf_event's perf report, despite -fno-omit-frame-pointer compilation Mark Davis
2016-04-19 0:18 ` David Ahern
2016-04-25 9:01 ` Milian Wolff
2016-04-26 1:03 ` Arnaldo Carvalho de Melo
2016-04-26 1:24 ` LBR callchains from tracepoints Arnaldo Carvalho de Melo
2016-04-26 16:38 ` Peter Zijlstra [this message]
2016-04-26 17:26 ` Alexei Starovoitov
2016-04-26 18:20 ` Arnaldo Carvalho de Melo
2016-04-26 19:07 ` Peter Zijlstra
2016-04-19 2:26 ` Missing stack symbols with perf_event's perf report, despite -fno-omit-frame-pointer compilation Taeung Song
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