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Subject[PATCH 0/9] TopDown metrics support for Icelake
From: Kan Liang <>

Icelake has support for measuring the level 1 TopDown metrics
directly in hardware. This is implemented by an additional METRICS
register, and a new Fixed Counter 3 that measures pipeline SLOTS.

Four TopDown metric events as separate perf events, which map to
internal METRICS register, are exposed. They are topdown-retiring,
topdown-bad-spec, topdown-fe-bound and topdown-be-bound.
Those events do not exist in hardware, but can be allocated by the
scheduler. We use a special 0xff event code, which is reserved for
software. The value of TopDown metric events can be calculated by
multiplying the METRICS (percentage) register with SLOTS fixed counter.

New in Icelake
- Do not require generic counters. This allows to collect TopDown always
in addition to other events.
- Measuring TopDown per thread/process instead of only per core

- To get accurate result and avoid reading the METRICS register multiple
times, the TopDown metrics events and SLOTS event have to be in the
same group.
- METRICS and SLOTS registers have to be cleared after each read by SW.
That is to prevent the lose of precision and a known side effect of
METRICS register.
- Cannot do sampling read SLOTS and TopDown metric events

Please refer SDM Vol3, Performance Metrics for the details of
TopDown metrics.

Andi Kleen (7):
perf/core: Support a REMOVE transaction
perf/x86/intel: Basic support for metrics counters
perf/x86/intel: Support overflows on SLOTS
perf/x86/intel: Set correct weight for TopDown metrics events
perf/x86/intel: Export new TopDown metrics events for Icelake
perf, tools, stat: Support new per thread TopDown metrics
perf, tools: Add documentation for topdown metrics

Kan Liang (2):
perf/x86/intel: Support hardware TopDown metrics
perf/x86/intel: Disable sampling read slots and topdown

arch/x86/events/core.c | 63 ++++++--
arch/x86/events/intel/core.c | 284 +++++++++++++++++++++++++++++++--
arch/x86/events/perf_event.h | 31 ++++
arch/x86/include/asm/msr-index.h | 3 +
arch/x86/include/asm/perf_event.h | 30 ++++
include/linux/perf_event.h | 7 +
kernel/events/core.c | 5 +
tools/perf/Documentation/perf-stat.txt | 9 +-
tools/perf/Documentation/topdown.txt | 223 ++++++++++++++++++++++++++
tools/perf/builtin-stat.c | 24 +++
tools/perf/util/stat-shadow.c | 89 +++++++++++
tools/perf/util/stat.c | 4 +
tools/perf/util/stat.h | 8 +
13 files changed, 754 insertions(+), 26 deletions(-)
create mode 100644 tools/perf/Documentation/topdown.txt


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