Re: [PATCH v2 1/2] perf arm-spe: Use SPE data source for neoverse cores

German Gomez
2022-03-02T12:00:08Z

Hi Ali,

On 21/02/2022 22:47, Ali Saidi wrote:
> When synthesizing data from SPE, augment the type with source information
> for Arm Neoverse cores. The field is IMPLDEF but the Neoverse cores all use
> the same encoding. I can't find encoding information for any other SPE
> implementations to unify their choices with Arm's thus that is left for
> future work.
>
> This change populates the mem_lvl_num for Neoverse cores instead of the
> deprecated mem_lvl namespace.
>
> Signed-off-by: Ali Saidi <alisaidi@amazon.com>
> ---
> .../util/arm-spe-decoder/arm-spe-decoder.c | 1 +
> .../util/arm-spe-decoder/arm-spe-decoder.h | 12 ++
> tools/perf/util/arm-spe.c | 106 +++++++++++++++---
> 3 files changed, 104 insertions(+), 15 deletions(-)
>
> diff --git a/tools/perf/util/arm-spe-decoder/arm-spe-decoder.c b/tools/perf/util/arm-spe-decoder/arm-spe-decoder.c
> index 5e390a1a79ab..091987dd3966 100644
> --- a/tools/perf/util/arm-spe-decoder/arm-spe-decoder.c
> +++ b/tools/perf/util/arm-spe-decoder/arm-spe-decoder.c
> @@ -220,6 +220,7 @@ static int arm_spe_read_record(struct arm_spe_decoder *decoder)
>
> break;
> case ARM_SPE_DATA_SOURCE:
> + decoder->record.source = payload;
> break;
> case ARM_SPE_BAD:
> break;
> 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 69b31084d6be..c81bf90c0996 100644
> --- a/tools/perf/util/arm-spe-decoder/arm-spe-decoder.h
> +++ b/tools/perf/util/arm-spe-decoder/arm-spe-decoder.h
> @@ -29,6 +29,17 @@ enum arm_spe_op_type {
> ARM_SPE_ST = 1 << 1,
> };
>
> +enum arm_spe_neoverse_data_source {
> + ARM_SPE_NV_L1D = 0x0,
> + ARM_SPE_NV_L2 = 0x8,
> + ARM_SPE_NV_PEER_CORE = 0x9,
> + ARM_SPE_NV_LCL_CLSTR = 0xa,
> + ARM_SPE_NV_SYS_CACHE = 0xb,
> + ARM_SPE_NV_PEER_CLSTR = 0xc,
> + ARM_SPE_NV_REMOTE = 0xd,
> + ARM_SPE_NV_DRAM = 0xe,
> +};
> +
> struct arm_spe_record {
> enum arm_spe_sample_type type;
> int err;
> @@ -40,6 +51,7 @@ struct arm_spe_record {
> u64 virt_addr;
> u64 phys_addr;
> u64 context_id;
> + u16 source;
> };
>
> struct arm_spe_insn;
> diff --git a/tools/perf/util/arm-spe.c b/tools/perf/util/arm-spe.c
> index d2b64e3f588b..e0243c2fed5f 100644
> --- a/tools/perf/util/arm-spe.c
> +++ b/tools/perf/util/arm-spe.c
> @@ -34,6 +34,7 @@
> #include "arm-spe-decoder/arm-spe-decoder.h"
> #include "arm-spe-decoder/arm-spe-pkt-decoder.h"
>
> +#include <../../../arch/arm64/include/asm/cputype.h>
> #define MAX_TIMESTAMP (~0ULL)
>
> struct arm_spe {
> @@ -45,6 +46,7 @@ struct arm_spe {
> struct perf_session *session;
> struct machine *machine;
> u32 pmu_type;
> + u64 midr;
>
> struct perf_tsc_conversion tc;
>
> @@ -399,33 +401,103 @@ static bool arm_spe__is_memory_event(enum arm_spe_sample_type type)
> return false;
> }
>
> -static u64 arm_spe__synth_data_source(const struct arm_spe_record *record)
> -{
> - union perf_mem_data_src data_src = { 0 };
> +static const struct midr_range neoverse_spe[] = {
> + MIDR_ALL_VERSIONS(MIDR_NEOVERSE_N1),
> + MIDR_ALL_VERSIONS(MIDR_NEOVERSE_N2),
> + {},
> +};
>
> - if (record->op == ARM_SPE_LD)
> - data_src.mem_op = PERF_MEM_OP_LOAD;
> - else
> - data_src.mem_op = PERF_MEM_OP_STORE;
>
> +static void arm_spe__synth_data_source_neoverse(const struct arm_spe_record *record,
> + union perf_mem_data_src *data_src)
> +{
> + switch (record->source) {
> + case ARM_SPE_NV_L1D:
> + data_src->mem_lvl = PERF_MEM_LVL_HIT;

I understand mem_lvl is deprecated but shouldn't we add the level bits here as well for backwards compat?

> + data_src->mem_lvl_num = PERF_MEM_LVLNUM_L1;
> + break;
> + case ARM_SPE_NV_L2:
> + data_src->mem_lvl = PERF_MEM_LVL_HIT;
> + data_src->mem_lvl_num = PERF_MEM_LVLNUM_L2;
> + break;
> + case ARM_SPE_NV_PEER_CORE:
> + data_src->mem_lvl = PERF_MEM_LVL_HIT;
> + data_src->mem_snoop = PERF_MEM_SNOOP_HITM;
> + data_src->mem_lvl_num = PERF_MEM_LVLNUM_ANY_CACHE;
> + break;
> + /*
> + * We don't know if this is L1, L2, or even L3 (for the cases the system
> + * has an L3, but we do know it was a cache-2-cache transfer, so set
> + * SNOOP_HITM
> + */
> + case ARM_SPE_NV_LCL_CLSTR:
> + case ARM_SPE_NV_PEER_CLSTR:
> + data_src->mem_lvl = PERF_MEM_LVL_HIT;
> + data_src->mem_snoop = PERF_MEM_SNOOP_HITM;
> + data_src->mem_lvl_num = PERF_MEM_LVLNUM_ANY_CACHE;
> + break;
> + /*
> + * System cache is assumed to be L4, as cluster cache (if it exists)
> + * would be L3 cache on Neoverse platforms
> + */
> + case ARM_SPE_NV_SYS_CACHE:
> + data_src->mem_lvl = PERF_MEM_LVL_HIT;
> + data_src->mem_lvl_num = PERF_MEM_LVLNUM_L4;
> + break;
> + /*
> + * We don't know what level it hit in, except it came from the other
> + * socket
> + */
> + case ARM_SPE_NV_REMOTE:
> + data_src->mem_snoop = PERF_MEM_SNOOP_HITM;
> + data_src->mem_remote = PERF_MEM_REMOTE_REMOTE;
> + break;
> + case ARM_SPE_NV_DRAM:
> + data_src->mem_lvl = PERF_MEM_LVL_HIT;
> + data_src->mem_lvl_num = PERF_MEM_LVLNUM_RAM;
> + break;
> + default:
> + break;
> + }
> +}
> +
> +static void arm_spe__synth_data_source_generic(const struct arm_spe_record *record,
> + union perf_mem_data_src *data_src)
> +{
> if (record->type & (ARM_SPE_LLC_ACCESS | ARM_SPE_LLC_MISS)) {
> - data_src.mem_lvl = PERF_MEM_LVL_L3;
> + data_src->mem_lvl = PERF_MEM_LVL_L3;
>
> if (record->type & ARM_SPE_LLC_MISS)
> - data_src.mem_lvl |= PERF_MEM_LVL_MISS;
> + data_src->mem_lvl |= PERF_MEM_LVL_MISS;
> else
> - data_src.mem_lvl |= PERF_MEM_LVL_HIT;
> + data_src->mem_lvl |= PERF_MEM_LVL_HIT;
> } else if (record->type & (ARM_SPE_L1D_ACCESS | ARM_SPE_L1D_MISS)) {
> - data_src.mem_lvl = PERF_MEM_LVL_L1;
> + data_src->mem_lvl = PERF_MEM_LVL_L1;
>
> if (record->type & ARM_SPE_L1D_MISS)
> - data_src.mem_lvl |= PERF_MEM_LVL_MISS;
> + data_src->mem_lvl |= PERF_MEM_LVL_MISS;
> else
> - data_src.mem_lvl |= PERF_MEM_LVL_HIT;
> + data_src->mem_lvl |= PERF_MEM_LVL_HIT;
> }
>
> if (record->type & ARM_SPE_REMOTE_ACCESS)
> - data_src.mem_lvl |= PERF_MEM_LVL_REM_CCE1;
> + data_src->mem_lvl |= PERF_MEM_LVL_REM_CCE1;
> +}
> +
> +static u64 arm_spe__synth_data_source(const struct arm_spe_record *record, u64 midr)
> +{
> + union perf_mem_data_src data_src = { 0 };
> + bool is_neoverse = is_midr_in_range(midr, neoverse_spe);
> +
> + if (record->op & ARM_SPE_LD)
> + data_src.mem_op = PERF_MEM_OP_LOAD;
> + else
> + data_src.mem_op = PERF_MEM_OP_STORE;
> +
> + if (is_neoverse)
> + arm_spe__synth_data_source_neoverse(record, &data_src);
> + else
> + arm_spe__synth_data_source_generic(record, &data_src);
>
> if (record->type & (ARM_SPE_TLB_ACCESS | ARM_SPE_TLB_MISS)) {
> data_src.mem_dtlb = PERF_MEM_TLB_WK;
> @@ -446,7 +518,7 @@ static int arm_spe_sample(struct arm_spe_queue *speq)
> u64 data_src;
> int err;
>
> - data_src = arm_spe__synth_data_source(record);
> + data_src = arm_spe__synth_data_source(record, spe->midr);
>
> if (spe->sample_flc) {
> if (record->type & ARM_SPE_L1D_MISS) {
> @@ -796,6 +868,10 @@ static int arm_spe_process_event(struct perf_session *session,
> u64 timestamp;
> struct arm_spe *spe = container_of(session->auxtrace,
> struct arm_spe, auxtrace);
> + const char *cpuid = perf_env__cpuid(session->evlist->env);
> + u64 midr = strtol(cpuid, NULL, 16);
> +
> + spe->midr = midr;

I think this midr setup belongs in the arm_spe_process_auxtrace_info callback instead.

Thanks,
German

>
> if (dump_trace)
> return 0;