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SubjectRe: [PATCH v3] perf arm-spe: Synthesize SPE instruction events
On Thu, Dec 16, 2021 at 7:24 AM German Gomez <german.gomez@arm.com> wrote:
>
> Synthesize instruction events for every ARM SPE record.
>
> Arm SPE implements a hardware-based sample period, and perf implements a
> software-based one. Add a warning message to inform the user of this.
>
> Signed-off-by: German Gomez <german.gomez@arm.com>

Acked-by: Namhyung Kim <namhyung@kernel.org>

Thanks,
Namhyung


> ---
> Changes since v2
> - Rebase patch on top of https://lore.kernel.org/r/20211201220855.1260688-1-namhyung@kernel.org
> - Don't error out when using unsupported sample period type.
> - Store instructions_sample_period into samples.
> Changes since v1 [https://lore.kernel.org/all/20211117142833.226629-1-german.gomez@arm.com]
> - Generate events with "--itrace=i" instead of "--itrace=o".
> - Generate events with virt_addr, phys_addr, and data_src values.
> ---
> tools/perf/util/arm-spe.c | 62 +++++++++++++++++++++++++++++++++++++++
> 1 file changed, 62 insertions(+)
>
> diff --git a/tools/perf/util/arm-spe.c b/tools/perf/util/arm-spe.c
> index 8a3828f86901..d2b64e3f588b 100644
> --- a/tools/perf/util/arm-spe.c
> +++ b/tools/perf/util/arm-spe.c
> @@ -58,6 +58,8 @@ struct arm_spe {
> u8 sample_branch;
> u8 sample_remote_access;
> u8 sample_memory;
> + u8 sample_instructions;
> + u64 instructions_sample_period;
>
> u64 l1d_miss_id;
> u64 l1d_access_id;
> @@ -68,6 +70,7 @@ struct arm_spe {
> u64 branch_miss_id;
> u64 remote_access_id;
> u64 memory_id;
> + u64 instructions_id;
>
> u64 kernel_start;
>
> @@ -90,6 +93,7 @@ struct arm_spe_queue {
> u64 time;
> u64 timestamp;
> struct thread *thread;
> + u64 period_instructions;
> };
>
> static void arm_spe_dump(struct arm_spe *spe __maybe_unused,
> @@ -202,6 +206,7 @@ static struct arm_spe_queue *arm_spe__alloc_queue(struct arm_spe *spe,
> speq->pid = -1;
> speq->tid = -1;
> speq->cpu = -1;
> + speq->period_instructions = 0;
>
> /* params set */
> params.get_trace = arm_spe_get_trace;
> @@ -353,6 +358,35 @@ static int arm_spe__synth_branch_sample(struct arm_spe_queue *speq,
> return arm_spe_deliver_synth_event(spe, speq, event, &sample);
> }
>
> +static int arm_spe__synth_instruction_sample(struct arm_spe_queue *speq,
> + u64 spe_events_id, u64 data_src)
> +{
> + struct arm_spe *spe = speq->spe;
> + struct arm_spe_record *record = &speq->decoder->record;
> + union perf_event *event = speq->event_buf;
> + struct perf_sample sample = { .ip = 0, };
> +
> + /*
> + * Handles perf instruction sampling period.
> + */
> + speq->period_instructions++;
> + if (speq->period_instructions < spe->instructions_sample_period)
> + return 0;
> + speq->period_instructions = 0;
> +
> + arm_spe_prep_sample(spe, speq, event, &sample);
> +
> + sample.id = spe_events_id;
> + sample.stream_id = spe_events_id;
> + sample.addr = record->virt_addr;
> + sample.phys_addr = record->phys_addr;
> + sample.data_src = data_src;
> + sample.period = spe->instructions_sample_period;
> + sample.weight = record->latency;
> +
> + return arm_spe_deliver_synth_event(spe, speq, event, &sample);
> +}
> +
> #define SPE_MEM_TYPE (ARM_SPE_L1D_ACCESS | ARM_SPE_L1D_MISS | \
> ARM_SPE_LLC_ACCESS | ARM_SPE_LLC_MISS | \
> ARM_SPE_REMOTE_ACCESS)
> @@ -482,6 +516,12 @@ static int arm_spe_sample(struct arm_spe_queue *speq)
> return err;
> }
>
> + if (spe->sample_instructions) {
> + err = arm_spe__synth_instruction_sample(speq, spe->instructions_id, data_src);
> + if (err)
> + return err;
> + }
> +
> return 0;
> }
>
> @@ -1110,7 +1150,29 @@ arm_spe_synth_events(struct arm_spe *spe, struct perf_session *session)
> return err;
> spe->memory_id = id;
> arm_spe_set_event_name(evlist, id, "memory");
> + id += 1;
> + }
> +
> + if (spe->synth_opts.instructions) {
> + if (spe->synth_opts.period_type != PERF_ITRACE_PERIOD_INSTRUCTIONS) {
> + pr_warning("Only instruction-based sampling period is currently supported by Arm SPE.\n");
> + goto synth_instructions_out;
> + }
> + if (spe->synth_opts.period > 1)
> + pr_warning("Arm SPE has a hardware-based sample period.\n"
> + "Additional instruction events will be discarded by --itrace\n");
> +
> + spe->sample_instructions = true;
> + attr.config = PERF_COUNT_HW_INSTRUCTIONS;
> + attr.sample_period = spe->synth_opts.period;
> + spe->instructions_sample_period = attr.sample_period;
> + err = arm_spe_synth_event(session, &attr, id);
> + if (err)
> + return err;
> + spe->instructions_id = id;
> + arm_spe_set_event_name(evlist, id, "instructions");
> }
> +synth_instructions_out:
>
> return 0;
> }
> --
> 2.25.1
>

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