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[PATCH 00/14] perf cs-etm: Per-thread mode fixes and snapshot wrap support

From: James Clark <james.clark@linaro.org>
Date: 2026-08-11 15:30:57
Also in: linux-doc, linux-perf-users, lkml

Fix a few issues with per-thread mode:
  - With TRBE, thread migrations hit a queue without a decoder assert
  - On nVHE, everything looks like guest trace instead of host
  - Tracing multiple threads didn't really work

After adding a tests for those, it turns out there were some snapshot
bugs not picked up by the other snapshot tests. That showed that the
different snapshot searches for Intel BTS and Arm SPE were inconsistent
and I think all tracers can benefit from using the same pointer fixup
logic, so that gets refactored into the common auxtrace.c. Then SPE can
just share the Intel BTS search as it was obviously copied from it
originally. IntelPT keeps the more advanced duplicate data search, but
in the future that could probably be made the common one and all tracers
would benefit from using it (except maybe BTS if it always has a very
small buffer, but I doubt the overhead of the duplicate search would be
an issue). For now this is more of a refactor rather than behavioral
change so don't do that yet.

Signed-off-by: James Clark <james.clark@linaro.org>
---
James Clark (14):
      perf cs-etm: Fix nVHE per-thread decoding
      perf cs-etm: Warn for invalid timestamp option
      perf cs-etm: Turn on context packet timestamps in per-thread mode
      perf cs-etm: Use per-CPU queues for per-thread mode
      perf cs-etm: Increase default timestamp generation period
      perf auxtrace: Turn Intel BTS snapshot search into a generic one
      perf arm-spe: Use generic snapshot search
      perf auxtrace: intel-pt: Use new snapshot_has_wrapped callback
      perf cs-etm: Queue partial AUX records
      perf cs-etm: Don't print missing buffers in snapshot mode
      perf auxtrace: cs-etm: Capture wrapped snapshots
      perf test: Allow infinite named_thread loops
      perf test: Add test for per-thread mode
      perf cs-etm: Test multiple per-thread threads

 Documentation/userspace-api/perf_ring_buffer.rst   |   6 +-
 tools/perf/Documentation/perf-test.txt             |   2 +-
 tools/perf/arch/arm/util/cs-etm.c                  |  30 ++++-
 tools/perf/arch/arm64/util/arm-spe.c               | 147 +--------------------
 tools/perf/arch/x86/util/intel-bts.c               | 115 +---------------
 tools/perf/arch/x86/util/intel-pt.c                |  58 +++-----
 .../perf/tests/shell/coresight/per-thread-multi.sh |  78 +++++++++++
 tools/perf/tests/shell/coresight/per-thread.sh     |  48 +++++++
 .../perf/tests/shell/coresight/raw_dump_stress.sh  |   5 -
 tools/perf/tests/workloads/named_threads.c         |   7 +-
 tools/perf/util/auxtrace.c                         | 136 +++++++++++++++++--
 tools/perf/util/auxtrace.h                         |  20 ++-
 tools/perf/util/cs-etm.c                           |  98 ++++++++++----
 13 files changed, 382 insertions(+), 368 deletions(-)
---
base-commit: bf10e6ee2ac3034c9068e03eed418fd16961984e
change-id: 20260605-james-cs-unformatted-per-thread-fix-50e723aa7f0e

Best regards,
--  
James Clark [off-list ref]

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