Re: [RFC PATCH 00/25] Perf stat metric grouping with hardware information

From: Liang, Kan
Date: Tue Sep 26 2023 - 10:43:40 EST



On 2023-09-25 2:17 a.m., weilin.wang@xxxxxxxxx wrote:
> From: Weilin Wang <weilin.wang@xxxxxxxxx>
>
> Perf stat metric grouping generates event groups that are provided to kernel for
> data collection using the hardware counters. Sometimes, the grouping might fail
> and kernel has to retry the groups because generated groups do not fit in the
> hardware counters correctly. In some other cases, the groupings are collected
> correctly, however, they left some hardware counters unused.
>
> To improve these inefficiencies, we would like to propose a hardware aware
> grouping method that does metric/event grouping based on event counter
> restriction rules and the availability of hardware counters in the system. This
> method is generic as long as all the restriction rules could be provided from
> the pmu-event JSON files.

This method assumes that it's the only user (expect NMI watchdog) and
all the HW resource are available. Right?

>
> This patch set includes code that does hardware aware grouping and updated
> pmu-event JSON files for four platforms (SapphireRapids, Icelakex, Cascadelakex,
> and Tigerlake) for your testing and experimenting. We've successfully tested
> these patches on three platforms (SapphireRapids, Icelakex, and Cascadelakex)
> with topdown metrics from TopdownL1 to TopdownL6.
>
> There are some optimization opportunities that we might implement in the future:
> 1) Better NMI hanlding: when NMI watchdog is enabled, we reduce the default_core
> total counter size by one. This could be improved to better utilize the counter.
> 2) Fill important events into unused counter for better counter utlization:
> there might be some unused counters scattered in the groups. We could consider
> to add important events in this slots if necessary. This could help increase the
> multiplexing percentage and help improve accuracy if the event is critical.
>
> Remaining questions for dicussion:
> 3) Where to start grouping from? The current implementation start grouping by
> combining all the events into a single list. This step deduplicates events. But
> it does not maintain the relationship of events according to the metrics, i.e.
> events required by one metric may not be collected at the same time. Another
> type of starting point would be grouping each individual metric and then try to
> merge the groups.

Maybe you can add a new flag to tag the metric which should/better be
scheduled together, e.g., IPC.

Thanks,
Kan
> 4) Any comments, suggestions, new ideas?
> 5) If you are interested to test the patch out and the pmu-event JSON files of
> your testing platform is not provided here, please let me know so that I could
> provide you the files.
>
>
> Weilin Wang (25):
> perf stat: Add hardware-grouping cmd option to perf stat
> perf stat: Add basic functions for the hardware-grouping stat cmd
> option
> perf pmu-events: Add functions in jevent.py
> perf pmu-events: Add counter info into JSON files for SapphireRapids
> perf pmu-events: Add event counter data for Cascadelakex
> perf pmu-events: Add event counter data for Icelakex
> perf stat: Add helper functions for hardware-grouping method
> perf stat: Add functions to get counter info
> perf stat: Add helper functions for hardware-grouping method
> perf stat: Add helper functions to hardware-grouping method
> perf stat: Add utility functions to hardware-grouping method
> perf stat: Add more functions for hardware-grouping method
> perf stat: Add functions to hardware-grouping method
> perf stat: Add build string function and topdown events handling in
> hardware-grouping
> perf stat: Add function to combine metrics for hardware-grouping
> perf stat: Update keyword core to default_core to adjust to the
> changes for events with no unit
> perf stat: Handle taken alone in hardware-grouping
> perf stat: Handle NMI in hardware-grouping
> perf stat: Handle grouping method fall back in hardware-grouping
> perf stat: Code refactoring in hardware-grouping
> perf stat: Add tool events support in hardware-grouping
> perf stat: Add TSC support in hardware-grouping
> perf stat: Fix a return error issue in hardware-grouping
> perf stat: Add check to ensure correctness in platform that does not
> support hardware-grouping
> perf pmu-events: Add event counter data for Tigerlake
>
> tools/lib/bitmap.c | 20 +
> tools/perf/builtin-stat.c | 7 +
> .../arch/x86/cascadelakex/cache.json | 1237 ++++++++++++
> .../arch/x86/cascadelakex/counter.json | 17 +
> .../arch/x86/cascadelakex/floating-point.json | 16 +
> .../arch/x86/cascadelakex/frontend.json | 68 +
> .../arch/x86/cascadelakex/memory.json | 751 ++++++++
> .../arch/x86/cascadelakex/other.json | 168 ++
> .../arch/x86/cascadelakex/pipeline.json | 102 +
> .../arch/x86/cascadelakex/uncore-cache.json | 1138 +++++++++++
> .../x86/cascadelakex/uncore-interconnect.json | 1272 +++++++++++++
> .../arch/x86/cascadelakex/uncore-io.json | 394 ++++
> .../arch/x86/cascadelakex/uncore-memory.json | 509 +++++
> .../arch/x86/cascadelakex/uncore-power.json | 25 +
> .../arch/x86/cascadelakex/virtual-memory.json | 28 +
> .../pmu-events/arch/x86/icelakex/cache.json | 98 +
> .../pmu-events/arch/x86/icelakex/counter.json | 17 +
> .../arch/x86/icelakex/floating-point.json | 13 +
> .../arch/x86/icelakex/frontend.json | 55 +
> .../pmu-events/arch/x86/icelakex/memory.json | 53 +
> .../pmu-events/arch/x86/icelakex/other.json | 52 +
> .../arch/x86/icelakex/pipeline.json | 92 +
> .../arch/x86/icelakex/uncore-cache.json | 965 ++++++++++
> .../x86/icelakex/uncore-interconnect.json | 1667 +++++++++++++++++
> .../arch/x86/icelakex/uncore-io.json | 966 ++++++++++
> .../arch/x86/icelakex/uncore-memory.json | 186 ++
> .../arch/x86/icelakex/uncore-power.json | 26 +
> .../arch/x86/icelakex/virtual-memory.json | 22 +
> .../arch/x86/sapphirerapids/cache.json | 104 +
> .../arch/x86/sapphirerapids/counter.json | 17 +
> .../x86/sapphirerapids/floating-point.json | 25 +
> .../arch/x86/sapphirerapids/frontend.json | 98 +-
> .../arch/x86/sapphirerapids/memory.json | 44 +
> .../arch/x86/sapphirerapids/other.json | 40 +
> .../arch/x86/sapphirerapids/pipeline.json | 118 ++
> .../arch/x86/sapphirerapids/uncore-cache.json | 534 +++++-
> .../arch/x86/sapphirerapids/uncore-cxl.json | 56 +
> .../sapphirerapids/uncore-interconnect.json | 476 +++++
> .../arch/x86/sapphirerapids/uncore-io.json | 373 ++++
> .../x86/sapphirerapids/uncore-memory.json | 391 ++++
> .../arch/x86/sapphirerapids/uncore-power.json | 24 +
> .../x86/sapphirerapids/virtual-memory.json | 20 +
> .../pmu-events/arch/x86/tigerlake/cache.json | 65 +
> .../arch/x86/tigerlake/counter.json | 7 +
> .../arch/x86/tigerlake/floating-point.json | 13 +
> .../arch/x86/tigerlake/frontend.json | 56 +
> .../pmu-events/arch/x86/tigerlake/memory.json | 31 +
> .../pmu-events/arch/x86/tigerlake/other.json | 4 +
> .../arch/x86/tigerlake/pipeline.json | 96 +
> .../x86/tigerlake/uncore-interconnect.json | 11 +
> .../arch/x86/tigerlake/uncore-memory.json | 6 +
> .../arch/x86/tigerlake/uncore-other.json | 1 +
> .../arch/x86/tigerlake/virtual-memory.json | 20 +
> tools/perf/pmu-events/jevents.py | 179 +-
> tools/perf/pmu-events/pmu-events.h | 26 +-
> tools/perf/util/metricgroup.c | 927 +++++++++
> tools/perf/util/metricgroup.h | 82 +
> tools/perf/util/pmu.c | 5 +
> tools/perf/util/pmu.h | 1 +
> tools/perf/util/stat.h | 1 +
> 60 files changed, 13790 insertions(+), 25 deletions(-)
> create mode 100644 tools/perf/pmu-events/arch/x86/cascadelakex/counter.json
> create mode 100644 tools/perf/pmu-events/arch/x86/icelakex/counter.json
> create mode 100644 tools/perf/pmu-events/arch/x86/sapphirerapids/counter.json
> create mode 100644 tools/perf/pmu-events/arch/x86/tigerlake/counter.json
>
> --
> 2.39.3
>