[PATCH v4 0/3] perf alpha: Decode ProfileMe samples

[Matt Turner <mattst88@gmail.com>]

The Alpha kernel series "alpha/perf: add ProfileMe sampling" adds
ProfileMe sampling to the Alpha cpu PMU. Each ProfileMe sample carries
the profiled instruction's PMPC and its I_STAT and PCTR_CTL status as
PERF_SAMPLE_RAW data, which says whether the instruction 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:

  https://lore.kernel.org/r/20261104-alpha-profileme-v6-0-63362e9290a3@gmail.com

This series is the perf tool side. Patch 1 decodes the raw data in perf
report -D and perf script -D, as is done for AMD IBS. It copies the new
uapi header from the kernel series into tools/arch, so it should wait
until that header is merged. Patch 2 adds a script that sums the status
by symbol or by instruction, in the style of DCPI. Patch 3 gives perf
mem a ProfileMe event, as the kernel series reports the DTB hits and
misses of loads and stores in the data source.

To try it, with the kernel series applied:

  perf record -R -e cpu/instructions,profileme/ -- ./workload
  tools/perf/python/alpha-profileme.py --pc

I tested this on an AlphaServer ES47 (EV7). Sampling a loop whose
branch tests random data reports that branch mispredicted in 21% of its
samples, and 0% with sorted data. As a normal user, perf mem record on
a loop that loads one word from each page reports the load's DTB hits
and misses.

Signed-off-by: Matt Turner <mattst88@gmail.com>
---
Changes in v4:
- Patches 1 and 2: ignore TRP, and MIS and the trap type with it, for
  an instruction killed before it was mapped, as the kernel series
  does. Thanks to Ian Rogers.
- Patch 2: record cpu/instructions,profileme/ in the example, as a
  precise event now samples only retired instructions, which leaves
  the killed% and invalid% columns at 0. Thanks to Ian Rogers.
- New patch 3: add a perf mem event for Alpha, cpu/cycles,profileme/.
  Suggested by Ian Rogers.
- Link to v3: https://patch.msgid.link/20261102-perf-alpha-profileme-v3-0-4bf6e1dda733@gmail.com

Changes in v3:
- Patch 1: silence -Wpacked around the uapi header, which breaks the
  build where __u64 is 4-byte aligned, such as sh4.
- Patch 2: only read raw data from cpu PMU events, as a tracepoint's
  payload can pass for ProfileMe status. Thanks to Magnus Lindholm.
- Patch 2: print a table for each thing PCTR1 can count, so that mixing
  events no longer averages unrelated values. Thanks to Magnus Lindholm.
- Link to v2: https://patch.msgid.link/20261030-perf-alpha-profileme-v2-0-9ce2f0b0e622@gmail.com

Changes in v2:
- Patch 1: copy the raw data out of the sample and convert it from
  little endian, so that it decodes on strict-alignment and big-endian
  hosts.
- Patches 1 and 2: follow the new 28-byte struct alpha_profileme_sample
  from kernel v2.
- Link to v1: https://patch.msgid.link/20261028-perf-alpha-profileme-v1-0-f46c1938d001@gmail.com

---
Matt Turner (3):
      perf alpha: Decode ProfileMe raw samples
      perf python: Add alpha-profileme.py
      perf alpha: Add perf mem support

 tools/arch/alpha/include/uapi/asm/perf_event.h |  31 +++++
 tools/perf/Documentation/perf-mem.txt          |   3 +
 tools/perf/arch/alpha/Build                    |   2 +-
 tools/perf/arch/alpha/util/Build               |   2 +
 tools/perf/arch/alpha/util/mem-events.c        |  17 +++
 tools/perf/arch/alpha/util/mem-events.h        |   7 +
 tools/perf/arch/alpha/util/pmu.c               |  11 ++
 tools/perf/check-headers.sh                    |   1 +
 tools/perf/python/alpha-profileme.py           | 178 +++++++++++++++++++++++++
 tools/perf/util/Build                          |   1 +
 tools/perf/util/alpha-sample-raw.c             | 156 ++++++++++++++++++++++
 tools/perf/util/sample-raw.c                   |   2 +
 tools/perf/util/sample-raw.h                   |   2 +
 13 files changed, 412 insertions(+), 1 deletion(-)
---
base-commit: 4626d370ae89b8af4d46a45372b269f926ec662d
change-id: 20261028-perf-alpha-profileme-8010299be323

Best regards,
--  
Matt Turner <mattst88@gmail.com>