[RFC PATCH 00/15] perf: Fix the throttle logic for group

[kan.liang@linux.intel.com]

From: Kan Liang <kan.liang@linux.intel.com>

The sampling read doesn't work well with a group.
The issue was originally found by the 'Basic leader sampling test' case
failed on s390.
https://lore.kernel.org/all/20250228062241.303309-1-tmricht@linux.ibm.com/

Stephane debugged it and found it was caused by the throttling logic.
https://lore.kernel.org/all/CABPqkBQzCMNS_PfLZBWVuX9o8Z55PovwJvpVWMWzyeExFJ5R4Q@mail.gmail.com/

The throttle logic is generic and shared by all ARCHs.
It also impacts other ARCHs, e.g., X86.

On an Intel GNR machine,
$ perf record -e "{cycles,cycles}:S" ...

$ perf report -D | grep THROTTLE | tail -2
            THROTTLE events:        426  ( 9.0%)
          UNTHROTTLE events:        425  ( 9.0%)

$ perf report -D | grep PERF_RECORD_SAMPLE -a4 | tail -n 5
0 1020120874009167 0x74970 [0x68]: PERF_RECORD_SAMPLE(IP, 0x1):
... sample_read:
.... group nr 2
..... id 0000000000000327, value 000000000cbb993a, lost 0
..... id 0000000000000328, value 00000002211c26df, lost 0

The patch set tries to provide a generic fix for the group throttle
support. So the buggy driver-specific implementation can be removed.

The patch set is only verified on newer Intel platforms.

Kan Liang (15):
  perf: Fix the throttle logic for a group
  perf/x86/intel: Remove driver-specific throttle support
  perf/x86/amd: Remove driver-specific throttle support
  perf/x86/zhaoxin: Remove driver-specific throttle support
  powerpc/perf: Remove driver-specific throttle support
  s390/perf: Remove driver-specific throttle support
  perf/arm: Remove driver-specific throttle support
  perf/apple_m1: Remove driver-specific throttle support
  alpha/perf: Remove driver-specific throttle support
  arc/perf: Remove driver-specific throttle support
  csky/perf: Remove driver-specific throttle support
  loongarch/perf: Remove driver-specific throttle support
  sparc/perf: Remove driver-specific throttle support
  xtensa/perf: Remove driver-specific throttle support
  mips/perf: Remove driver-specific throttle support

 arch/alpha/kernel/perf_event.c       | 11 ++----
 arch/arc/kernel/perf_event.c         |  6 +--
 arch/csky/kernel/perf_event.c        |  3 +-
 arch/loongarch/kernel/perf_event.c   |  3 +-
 arch/mips/kernel/perf_event_mipsxx.c |  3 +-
 arch/powerpc/perf/core-book3s.c      |  6 +--
 arch/powerpc/perf/core-fsl-emb.c     |  3 +-
 arch/s390/kernel/perf_cpum_cf.c      |  2 -
 arch/s390/kernel/perf_cpum_sf.c      |  5 +--
 arch/sparc/kernel/perf_event.c       |  3 +-
 arch/x86/events/amd/core.c           |  3 +-
 arch/x86/events/amd/ibs.c            |  4 +-
 arch/x86/events/core.c               |  3 +-
 arch/x86/events/intel/core.c         |  6 +--
 arch/x86/events/intel/ds.c           |  7 ++--
 arch/x86/events/intel/knc.c          |  3 +-
 arch/x86/events/intel/p4.c           |  3 +-
 arch/x86/events/zhaoxin/core.c       |  3 +-
 arch/xtensa/kernel/perf_event.c      |  3 +-
 drivers/perf/apple_m1_cpu_pmu.c      |  3 +-
 drivers/perf/arm_pmuv3.c             |  3 +-
 drivers/perf/arm_v6_pmu.c            |  3 +-
 drivers/perf/arm_v7_pmu.c            |  3 +-
 drivers/perf/arm_xscale_pmu.c        |  6 +--
 kernel/events/core.c                 | 55 +++++++++++++++++++++-------
 25 files changed, 72 insertions(+), 81 deletions(-)

-- 
2.38.1