Re: [PATCH v3 1/2] perf arm-spe: Prepare for adding data source packet implementations for other cores

From: Ilkka Koskinen
Date: Thu Nov 07 2024 - 18:56:04 EST



Hi Leo,

On Thu, 7 Nov 2024, Leo Yan wrote:
Hi Ilkka,

This is a good refactoring for me. Just several minor comments.

On Wed, Nov 06, 2024 at 07:37:39PM +0000, Ilkka Koskinen wrote:

Split Data Source Packet handling to prepare adding support for
other implementations.

Signed-off-by: Ilkka Koskinen <ilkka@xxxxxxxxxxxxxxxxxxxxxx>
---
tools/perf/util/arm-spe.c | 65 ++++++++++++++++++++++++---------------
1 file changed, 40 insertions(+), 25 deletions(-)

diff --git a/tools/perf/util/arm-spe.c b/tools/perf/util/arm-spe.c
index dbf13f47879c..b222557cc27a 100644
--- a/tools/perf/util/arm-spe.c
+++ b/tools/perf/util/arm-spe.c
@@ -103,6 +103,18 @@ struct arm_spe_queue {
u32 flags;
};

+struct data_src {
+ struct midr_range midr_range;
+ void (*ds_synth)(const struct arm_spe_record *record,
+ union perf_mem_data_src *data_src);
+};

The naming is a bit mess. The data structure and the parameter both
are called "data_src", though this will not cause building issue.

How about rename the structure "data_src" to "data_source_handle" or
"data_source_class"?

Yeah, I forgot to revisit the naming part. I like "data"source_handle",
that should clarify it quite a bit.



For the "midr_range" field, I'd like to change it to a pointer:

struct midr_range *midr_range;

Please see below comments, which will present the reason for defining
it as a pointer.

+
+#define DS(range, func) \
+ { \
+ .midr_range = range, \
+ .ds_synth = arm_spe__synth_##func, \
+ }
+
static void arm_spe_dump(struct arm_spe *spe __maybe_unused,
unsigned char *buf, size_t len)
{
@@ -430,19 +442,6 @@ static int arm_spe__synth_instruction_sample(struct arm_spe_queue *speq,
return arm_spe_deliver_synth_event(spe, speq, event, &sample);
}

-static const struct midr_range common_ds_encoding_cpus[] = {
- MIDR_ALL_VERSIONS(MIDR_CORTEX_A720),
- MIDR_ALL_VERSIONS(MIDR_CORTEX_A725),
- MIDR_ALL_VERSIONS(MIDR_CORTEX_X1C),
- MIDR_ALL_VERSIONS(MIDR_CORTEX_X3),
- MIDR_ALL_VERSIONS(MIDR_CORTEX_X925),
- MIDR_ALL_VERSIONS(MIDR_NEOVERSE_N1),
- MIDR_ALL_VERSIONS(MIDR_NEOVERSE_N2),
- MIDR_ALL_VERSIONS(MIDR_NEOVERSE_V1),
- MIDR_ALL_VERSIONS(MIDR_NEOVERSE_V2),
- {},
-};

We can keep this data structure. For Ampere CPUs, you can add a new
data structure:

static const struct midr_range ampereone_ds_encoding_cpus[] = {
MIDR_ALL_VERSIONS(MIDR_AMPERE1A),
{},
};

Sounds good to me. I change all those.

Cheers, Ilkka



-
static void arm_spe__sample_flags(struct arm_spe_queue *speq)
{
const struct arm_spe_record *record = &speq->decoder->record;
@@ -532,6 +531,19 @@ static void arm_spe__synth_data_source_common(const struct arm_spe_record *recor
}
}

+static const struct data_src data_sources[] = {
+ DS(MIDR_ALL_VERSIONS(MIDR_CORTEX_A720), data_source_common),
+ DS(MIDR_ALL_VERSIONS(MIDR_CORTEX_A725), data_source_common),
+ DS(MIDR_ALL_VERSIONS(MIDR_CORTEX_X1C), data_source_common),
+ DS(MIDR_ALL_VERSIONS(MIDR_CORTEX_X3), data_source_common),
+ DS(MIDR_ALL_VERSIONS(MIDR_CORTEX_X925), data_source_common),
+ DS(MIDR_ALL_VERSIONS(MIDR_NEOVERSE_N1), data_source_common),
+ DS(MIDR_ALL_VERSIONS(MIDR_NEOVERSE_N2), data_source_common),
+ DS(MIDR_ALL_VERSIONS(MIDR_NEOVERSE_V1), data_source_common),
+ DS(MIDR_ALL_VERSIONS(MIDR_NEOVERSE_V2), data_source_common),
+ {},
+};
+

As a result, we can simplify the structure as:

static const struct data_src data_sources[] = {
DS(common_ds_encoding_cpus, data_source_common),
DS(ampereone_ds_encoding_cpus, data_source_ampereone),
};

static void arm_spe__synth_memory_level(const struct arm_spe_record *record,
union perf_mem_data_src *data_src)
{
@@ -555,12 +567,14 @@ static void arm_spe__synth_memory_level(const struct arm_spe_record *record,
data_src->mem_lvl |= PERF_MEM_LVL_REM_CCE1;
}

-static bool arm_spe__is_common_ds_encoding(struct arm_spe_queue *speq)
+static bool arm_spe__synth_ds(struct arm_spe_queue *speq,
+ const struct arm_spe_record *record,
+ union perf_mem_data_src *data_src)
{
struct arm_spe *spe = speq->spe;
- bool is_in_cpu_list;
+ const struct data_src *src = data_sources;
u64 *metadata = NULL;
- u64 midr = 0;
+ u64 midr;

/* Metadata version 1 assumes all CPUs are the same (old behavior) */
if (spe->metadata_ver == 1) {
@@ -592,18 +606,21 @@ static bool arm_spe__is_common_ds_encoding(struct arm_spe_queue *speq)
midr = metadata[ARM_SPE_CPU_MIDR];
}

- is_in_cpu_list = is_midr_in_range_list(midr, common_ds_encoding_cpus);
- if (is_in_cpu_list)
- return true;
- else
- return false;
+ while (src->midr_range.model) {
+ if (is_midr_in_range(midr, &src->midr_range)) {
+ src->ds_synth(record, data_src);
+ return true;
+ }
+ src++;
+ }

Here we can traverse the 'data_sources' array:

for (i = 0; i < ARRAY_SIZE(data_sources); i++) {
if (is_midr_in_range(midr, data_sources[i]->midr_range)) {
...
}
}

Thanks,
Leo

+
+ return false;
}

static u64 arm_spe__synth_data_source(struct arm_spe_queue *speq,
const struct arm_spe_record *record)
{
union perf_mem_data_src data_src = { .mem_op = PERF_MEM_OP_NA };
- bool is_common = arm_spe__is_common_ds_encoding(speq);

if (record->op & ARM_SPE_OP_LD)
data_src.mem_op = PERF_MEM_OP_LOAD;
@@ -612,9 +629,7 @@ static u64 arm_spe__synth_data_source(struct arm_spe_queue *speq,
else
return 0;

- if (is_common)
- arm_spe__synth_data_source_common(record, &data_src);
- else
+ if (!arm_spe__synth_ds(speq, record, &data_src))
arm_spe__synth_memory_level(record, &data_src);

if (record->type & (ARM_SPE_TLB_ACCESS | ARM_SPE_TLB_MISS)) {
--
2.47.0