Re: [PATCH v2 00/14] perf mem/c2c: Add support for AMD

[Jiri Olsa <olsajiri@gmail.com>]

On Thu, Jun 16, 2022 at 05:06:23PM +0530, Ravi Bangoria wrote:
> Perf mem and c2c tools are wrappers around perf record with mem load/
> store events. IBS tagged load/store sample provides most of the
> information needed for these tools. Enable support for these tools on
> AMD Zen processors based on IBS Op pmu.
> 
> There are some limitations though: Only load/store instructions provide
> mem/c2c information. However, IBS does not provide a way to choose a
> particular type of instruction to tag. This results in many non-LS
> instructions being tagged which appear as N/A. IBS, being an uncore pmu
> from kernel point of view[1], does not support per process monitoring.
> Thus, perf mem/c2c on AMD are currently supported in per-cpu mode only.
> 
> Example:
>   $ sudo ./perf mem record -- -c 10000
>   ^C[ perf record: Woken up 227 times to write data ]
>   [ perf record: Captured and wrote 58.760 MB perf.data (836978 samples) ]
> 
>   $ sudo ./perf mem report -F mem,sample,snoop
>   Samples: 836K of event 'ibs_op//', Event count (approx.): 8418762
>   Memory access                  Samples  Snoop
>   N/A                             700620  N/A
>   L1 hit                          126675  N/A
>   L2 hit                             424  N/A
>   L3 hit                             664  HitM
>   L3 hit                              10  N/A
>   Local RAM hit                        2  N/A
>   Remote RAM (1 hop) hit            8558  N/A
>   Remote Cache (1 hop) hit             3  N/A
>   Remote Cache (1 hop) hit             2  HitM
>   Remote Cache (2 hops) hit            10  HitM
>   Remote Cache (2 hops) hit             6  N/A
>   Uncached hit                         4  N/A
> 
> Prepared on amd/perf/core (9886142c7a22) + IBS Zen4 enhancement patches[2]
> 
> [1]: https://lore.kernel.org/lkml/20220113134743.1292-1-ravi.bangoria@amd.com
> [2]: https://lore.kernel.org/lkml/20220604044519.594-1-ravi.bangoria@amd.com
> 
> v1: https://lore.kernel.org/lkml/20220525093938.4101-1-ravi.bangoria@amd.com
> v1->v2:
>  - Instead of defining macros to extract IBS register bits, use existing
>    bitfield definitions. Zen4 has introduced additional set of bits in
>    IBS registers which this series also exploits and thus this series
>    now depends on IBS Zen4 enhancement patchset.
>  - Add support for PERF_SAMPLE_WEIGHT_STRUCT. While opening a new event,
>    perf tool starts with a set of attributes and goes on reverting some
>    attributes in a predefined order until it succeeds or run out or all
>    attempts. Here, 1st attempt includes WEIGHT_STRUCT and exclude_guest
>    which always fails because IBS does not support guest filtering. The
>    problem however is, perf reverts WEIGHT_STRUCT but keeps trying with
>    exclude_guest. Thus, although, this series enables WEIGHT_STRUCT
>    support from kernel, using it from the perf tool need more changes.
>    I'll try to address this bug later.
>  - Introduce __PERF_SAMPLE_CALLCHAIN_EARLY to hint generic perf driver
>    that physical address is set by arch pmu driver and should not be
>    overwritten.
> 
> 
> Ravi Bangoria (14):
>   perf/mem: Introduce PERF_MEM_LVLNUM_{EXTN_MEM|IO}
>   perf/x86/amd: Add IBS OP_DATA2 DataSrc bit definitions
>   perf/x86/amd: Support PERF_SAMPLE_DATA_SRC
>   perf/x86/amd: Support PERF_SAMPLE_{WEIGHT|WEIGHT_STRUCT}
>   perf/x86/amd: Support PERF_SAMPLE_ADDR
>   perf/x86/amd: Support PERF_SAMPLE_PHY_ADDR
>   perf tool: Sync include/uapi/linux/perf_event.h header
>   perf tool: Sync arch/x86/include/asm/amd-ibs.h header
>   perf mem: Add support for printing PERF_MEM_LVLNUM_{EXTN_MEM|IO}
>   perf mem/c2c: Set PERF_SAMPLE_WEIGHT for LOAD_STORE events
>   perf mem/c2c: Add load store event mappings for AMD
>   perf mem/c2c: Avoid printing empty lines for unsupported events
>   perf mem: Use more generic term for LFB
>   perf script: Add missing fields in usage hint

tools part looks good to me

Acked-by: Jiri Olsa <jolsa@kernel.org>

thanks,
jirka

> 
>  arch/x86/events/amd/ibs.c                | 372 ++++++++++++++++++++++-
>  arch/x86/include/asm/amd-ibs.h           |  16 +
>  include/uapi/linux/perf_event.h          |   5 +-
>  kernel/events/core.c                     |   4 +-
>  tools/arch/x86/include/asm/amd-ibs.h     |  16 +
>  tools/include/uapi/linux/perf_event.h    |   5 +-
>  tools/perf/Documentation/perf-c2c.txt    |  14 +-
>  tools/perf/Documentation/perf-mem.txt    |   3 +-
>  tools/perf/Documentation/perf-record.txt |   1 +
>  tools/perf/arch/x86/util/mem-events.c    |  31 +-
>  tools/perf/builtin-c2c.c                 |   1 +
>  tools/perf/builtin-mem.c                 |   1 +
>  tools/perf/builtin-script.c              |   7 +-
>  tools/perf/util/mem-events.c             |  17 +-
>  14 files changed, 467 insertions(+), 26 deletions(-)
> 
> -- 
> 2.31.1
>