Re: [PATCH v3 4/5] perf cs-etm: Optimize copying last branches

From: Mike Leach
Date: Thu Feb 06 2020 - 06:48:08 EST


Reviewed by: Mike Leach <mike.leach@xxxxxxxxxx>

On Mon, 3 Feb 2020 at 01:53, Leo Yan <leo.yan@xxxxxxxxxx> wrote:
>
> If an instruction range packet can generate multiple instruction
> samples, these samples share the same last branches; it's not necessary
> to copy the same last branches repeatedly for these samples within the
> same packet.
>
> This patch moves out the last branches copying from function
> cs_etm__synth_instruction_sample(), and execute it prior to generating
> instruction samples.
>
> Signed-off-by: Leo Yan <leo.yan@xxxxxxxxxx>
> ---
> tools/perf/util/cs-etm.c | 22 +++++++++++++++++-----
> 1 file changed, 17 insertions(+), 5 deletions(-)
>
> diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c
> index c5a05f728eac..dbddf1eec2be 100644
> --- a/tools/perf/util/cs-etm.c
> +++ b/tools/perf/util/cs-etm.c
> @@ -1134,10 +1134,8 @@ static int cs_etm__synth_instruction_sample(struct cs_etm_queue *etmq,
>
> cs_etm__copy_insn(etmq, tidq->trace_chan_id, tidq->packet, &sample);
>
> - if (etm->synth_opts.last_branch) {
> - cs_etm__copy_last_branch_rb(etmq, tidq);
> + if (etm->synth_opts.last_branch)
> sample.branch_stack = tidq->last_branch;
> - }
>
> if (etm->synth_opts.inject) {
> ret = cs_etm__inject_event(event, &sample,
> @@ -1407,6 +1405,10 @@ static int cs_etm__sample(struct cs_etm_queue *etmq,
> */
> u64 instrs_over = instrs_executed;
>
> + /* Prepare last branches for instruction sample */
> + if (etm->synth_opts.last_branch)
> + cs_etm__copy_last_branch_rb(etmq, tidq);
> +
> /*
> * 'head' is the instructions number of the head in the new
> * packet, it combines with the tail of previous packet to
> @@ -1526,6 +1528,11 @@ static int cs_etm__flush(struct cs_etm_queue *etmq,
>
> if (etmq->etm->synth_opts.last_branch &&
> tidq->prev_packet->sample_type == CS_ETM_RANGE) {
> + u64 addr;
> +
> + /* Prepare last branches for instruction sample */
> + cs_etm__copy_last_branch_rb(etmq, tidq);
> +
> /*
> * Generate a last branch event for the branches left in the
> * circular buffer at the end of the trace.
> @@ -1533,7 +1540,7 @@ static int cs_etm__flush(struct cs_etm_queue *etmq,
> * Use the address of the end of the last reported execution
> * range
> */
> - u64 addr = cs_etm__last_executed_instr(tidq->prev_packet);
> + addr = cs_etm__last_executed_instr(tidq->prev_packet);
>
> err = cs_etm__synth_instruction_sample(
> etmq, tidq, addr,
> @@ -1587,11 +1594,16 @@ static int cs_etm__end_block(struct cs_etm_queue *etmq,
> */
> if (etmq->etm->synth_opts.last_branch &&
> tidq->prev_packet->sample_type == CS_ETM_RANGE) {
> + u64 addr;
> +
> + /* Prepare last branches for instruction sample */
> + cs_etm__copy_last_branch_rb(etmq, tidq);
> +
> /*
> * Use the address of the end of the last reported execution
> * range.
> */
> - u64 addr = cs_etm__last_executed_instr(tidq->prev_packet);
> + addr = cs_etm__last_executed_instr(tidq->prev_packet);
>
> err = cs_etm__synth_instruction_sample(
> etmq, tidq, addr,
> --
> 2.17.1
>


--
Mike Leach
Principal Engineer, ARM Ltd.
Manchester Design Centre. UK