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Subject[PATCH v4 4/5] perf cs-etm: Optimize copying last branches
Date
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@linaro.org>
Reviewed-by: Mike Leach <mike.leach@linaro.org>
---
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 4b7d6c36ce3c..aa4b6d060ebb 100644
--- a/tools/perf/util/cs-etm.c
+++ b/tools/perf/util/cs-etm.c
@@ -1151,10 +1151,8 @@ 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,
@@ -1429,6 +1427,10 @@ static int cs_etm__sample(struct cs_etm_queue *etmq,
u64 offset = etm->instructions_sample_period - instrs_prev;
u64 addr;

+ /* Prepare last branches for instruction sample */
+ if (etm->synth_opts.last_branch)
+ cs_etm__copy_last_branch_rb(etmq, tidq);
+
while (tidq->period_instructions >=
etm->instructions_sample_period) {
/*
@@ -1506,6 +1508,11 @@ 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.
@@ -1513,7 +1520,7 @@ 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,
@@ -1558,11 +1565,16 @@ 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
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