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Message-ID: <ed15526d-9b1a-4204-92a3-4d319b03b790@linaro.org>
Date: Mon, 4 Nov 2024 11:47:06 +0000
From: James Clark <james.clark@...aro.org>
To: Ilkka Koskinen <ilkka@...amperecomputing.com>
Cc: linux-arm-kernel@...ts.infradead.org, linux-perf-users@...r.kernel.org,
linux-kernel@...r.kernel.org, John Garry <john.g.garry@...cle.com>,
Will Deacon <will@...nel.org>, Mike Leach <mike.leach@...aro.org>,
Leo Yan <leo.yan@...ux.dev>, Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...hat.com>, Arnaldo Carvalho de Melo <acme@...nel.org>,
Namhyung Kim <namhyung@...nel.org>, Mark Rutland <mark.rutland@....com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Jiri Olsa <jolsa@...nel.org>, Ian Rogers <irogers@...gle.com>,
Adrian Hunter <adrian.hunter@...el.com>,
"Liang, Kan" <kan.liang@...ux.intel.com>,
Graham Woodward <graham.woodward@....com>
Subject: Re: [PATCH v2 2/2] perf arm-spe: Add support for SPE Data Source
packet on AmpereOne
On 31/10/2024 9:35 pm, Ilkka Koskinen wrote:
> Decode SPE Data Source packets on AmpereOne. The field is IMPDEF.
>
> Signed-off-by: Ilkka Koskinen <ilkka@...amperecomputing.com>
> ---
> .../util/arm-spe-decoder/arm-spe-decoder.h | 9 +++
> tools/perf/util/arm-spe.c | 65 +++++++++++++++++++
> 2 files changed, 74 insertions(+)
>
> diff --git a/tools/perf/util/arm-spe-decoder/arm-spe-decoder.h b/tools/perf/util/arm-spe-decoder/arm-spe-decoder.h
> index 358c611eeddb..4bcd627e859f 100644
> --- a/tools/perf/util/arm-spe-decoder/arm-spe-decoder.h
> +++ b/tools/perf/util/arm-spe-decoder/arm-spe-decoder.h
> @@ -67,6 +67,15 @@ enum arm_spe_common_data_source {
> ARM_SPE_COMMON_DS_DRAM = 0xe,
> };
>
> +enum arm_spe_ampereone_data_source {
> + ARM_SPE_AMPEREONE_LOCAL_CHIP_CACHE_OR_DEVICE = 0x0,
> + ARM_SPE_AMPEREONE_SLC = 0x3,
> + ARM_SPE_AMPEREONE_REMOTE_CHIP_CACHE = 0x5,
> + ARM_SPE_AMPEREONE_DDR = 0x7,
> + ARM_SPE_AMPEREONE_L1D = 0x8,
> + ARM_SPE_AMPEREONE_L2D = 0x9,
> +};
> +
> struct arm_spe_record {
> enum arm_spe_sample_type type;
> int err;
> diff --git a/tools/perf/util/arm-spe.c b/tools/perf/util/arm-spe.c
> index 9586416be30a..700d4bc8d8ec 100644
> --- a/tools/perf/util/arm-spe.c
> +++ b/tools/perf/util/arm-spe.c
> @@ -103,6 +103,30 @@ struct arm_spe_queue {
> u32 flags;
> };
>
> +struct arm_spe_source_mapping {
> + u16 source;
> + enum arm_spe_common_data_source common_src;
> +};
> +
> +#define MAP_SOURCE(src, common) \
> + { \
> + .source = ARM_SPE_##src, \
> + .common_src = ARM_SPE_COMMON_##common, \
> + }
> +
> +static int arm_spe__map_to_common_source(u16 source,
> + struct arm_spe_source_mapping *tbl,
> + int nr_sources)
> +{
> + while (nr_sources--) {
> + if (tbl->source == source)
> + return tbl->common_src;
> + tbl++;
> + }
> +
Hi Ilkka,
I think a simple switch statement here would be easier to follow than
the loop, custom macro and then having the mappings in some other place:
switch(source)
case 0x0: /* AMPEREONE_LOCAL_CHIP_CACHE_OR_DEVICE */
return DS_PEER_CORE;
etc...
> + return -1;
And the default case can return 0xfff directly, which avoids the if else
later only to convert this -1 back into 0xfff.
> +}
> +
> static void arm_spe_dump(struct arm_spe *spe __maybe_unused,
> unsigned char *buf, size_t len)
> {
> @@ -443,6 +467,11 @@ static const struct midr_range common_ds_encoding_cpus[] = {
> {},
> };
>
> +static const struct midr_range ampereone_ds_encoding_cpus[] = {
> + MIDR_ALL_VERSIONS(MIDR_AMPERE1A),
> + {},
> +};
> +
> static void arm_spe__sample_flags(struct arm_spe_queue *speq)
> {
> const struct arm_spe_record *record = &speq->decoder->record;
> @@ -532,6 +561,38 @@ static void arm_spe__synth_data_source_common(const struct arm_spe_record *recor
> }
> }
>
> +static struct arm_spe_source_mapping ampereone_sources[] = {
> + MAP_SOURCE(AMPEREONE_LOCAL_CHIP_CACHE_OR_DEVICE, DS_PEER_CORE),
> + MAP_SOURCE(AMPEREONE_SLC, DS_SYS_CACHE),
> + MAP_SOURCE(AMPEREONE_REMOTE_CHIP_CACHE, DS_REMOTE),
> + MAP_SOURCE(AMPEREONE_DDR, DS_DRAM),
> + MAP_SOURCE(AMPEREONE_L1D, DS_L1D),
> + MAP_SOURCE(AMPEREONE_L2D, DS_L2),
> +};
> +
> +/*
> + * Source is IMPDEF. Here we convert the source code used on AmpereOne cores
> + * to the common (Neoverse, Cortex) to avoid duplicating the decoding code.
> + */
> +static void arm_spe__synth_data_source_ampereone(const struct arm_spe_record *record,
> + union perf_mem_data_src *data_src)
> +{
> + int common_src;
> + struct arm_spe_record common_record;
> +
> + common_src = arm_spe__map_to_common_source(record->source,
> + ampereone_sources,
> + ARRAY_SIZE(ampereone_sources));
> + if (common_src < 0)
> + /* Assign a bogus value that's not used for common coding */
> + common_record.source = 0xfff;
> + else
> + common_record.source = common_src;
> +
> + common_record.op = record->op;
> + arm_spe__synth_data_source_common(&common_record, data_src);
> +}
> +
> static void arm_spe__synth_memory_level(const struct arm_spe_record *record,
> union perf_mem_data_src *data_src)
> {
> @@ -606,6 +667,8 @@ static u64 arm_spe__synth_data_source(struct arm_spe_queue *speq,
> union perf_mem_data_src data_src = { .mem_op = PERF_MEM_OP_NA };
> bool is_common = arm_spe__is_ds_encoding_supported(speq,
> common_ds_encoding_cpus);
> + bool is_ampereone = arm_spe__is_ds_encoding_supported(speq,
> + ampereone_ds_encoding_cpus);
I know this probably already works, but we don't really need is_common
is_ampere etc, it will only grow anyway. All we need is a list of midrs
and function pairs. That also avoids doing is_ampereone even after we
already know is_common == true.
static const struct data_src[] = {
...
DS(MIDR_ALL_VERSIONS(MIDR_NEOVERSE_V2), common_ds),
DS(MIDR_ALL_VERSIONS(MIDR_AMPERE1A), ampere_ds),
{},
...
};
"arm_spe__is_ds_encoding_supported" then becomes a direct call to
"arm_spe__synth_ds" and we can drop the is_ampereone and is_common vars.
Then adding new ones doesn't require changing the function anymore.
>
> if (record->op & ARM_SPE_OP_LD)
> data_src.mem_op = PERF_MEM_OP_LOAD;
> @@ -616,6 +679,8 @@ static u64 arm_spe__synth_data_source(struct arm_spe_queue *speq,
>
> if (is_common)
> arm_spe__synth_data_source_common(record, &data_src);
> + else if (is_ampereone)
> + arm_spe__synth_data_source_ampereone(record, &data_src);
> else
> arm_spe__synth_memory_level(record, &data_src);
>
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