From: Peter Zijlstra <peterz@infradead.org>
To: Matt Turner <mattst88@gmail.com>
Cc: Richard Henderson <richard.henderson@linaro.org>,
Magnus Lindholm <linmag7@gmail.com>,
Ingo Molnar <mingo@redhat.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Namhyung Kim <namhyung@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Jiri Olsa <jolsa@kernel.org>, Ian Rogers <irogers@google.com>,
Adrian Hunter <adrian.hunter@intel.com>,
James Clark <james.clark@linaro.org>,
linux-alpha@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-perf-users@vger.kernel.org
Subject: Re: [PATCH 0/5] alpha/perf: add ProfileMe sampling
Date: Thu, 29 Oct 2026 10:11:41 +0100 [thread overview]
Message-ID: <20261029091141.GG1779021@noisy.programming.kicks-ass.net> (raw)
In-Reply-To: <20261028-alpha-profileme-v1-0-d44b52bf2500@gmail.com>
On Wed, Oct 28, 2026 at 02:09:29PM -0400, Matt Turner wrote:
> The 21264 from EV67 on, and the 21364, have a second performance counter
> mode, ProfileMe, alongside the Aggregate mode that the driver uses today.
> An Aggregate mode sample reports the PC where the overflow interrupt was
> taken. On an EV7 that is anywhere from 15 instructions before to 12
> after the one that overflowed the counter, which makes perf annotate
> output close to useless. In ProfileMe mode the CPU picks one fetched
> instruction, follows it down the pipeline, and reports its PC along with
> what happened to it: whether it retired, whether it trapped and why,
> whether it was a mispredicted branch, stalled before map, or was killed
> on a wrong path, and what PCTR1 counted while it was in flight.
Isn't this the thing that ended up as AMD's IBS?
prev parent reply other threads:[~2026-10-29 9:11 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-28 18:09 Matt Turner
2026-10-28 18:09 ` [PATCH 1/5] alpha/perf: pass PERFMON_CMD_LOGGING_ALL to the logging options call Matt Turner
2026-10-28 18:09 ` [PATCH 2/5] alpha/perf: add sysfs format and event attributes Matt Turner
2026-10-28 18:09 ` [PATCH 3/5] alpha/perf: implement ProfileMe sampling Matt Turner
2026-10-28 18:09 ` [PATCH 4/5] alpha/perf: attach ProfileMe status as PERF_SAMPLE_RAW data Matt Turner
2026-10-28 18:09 ` [PATCH 5/5] alpha/perf: optionally randomize the ProfileMe sampling interval Matt Turner
2026-10-29 9:11 ` Peter Zijlstra [this message]
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