From: Tavian Barnes <tavianator@tavianator.com>
To: linux-perf-users@vger.kernel.org
Cc: Tavian Barnes <tavianator@tavianator.com>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Namhyung Kim <namhyung@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Jiri Olsa <jolsa@kernel.org>, Ian Rogers <irogers@google.com>,
Adrian Hunter <adrian.hunter@intel.com>,
"Liang, Kan" <kan.liang@linux.intel.com>,
Andrew Kreimer <algonell@gmail.com>,
linux-kernel@vger.kernel.org
Subject: [PATCH] perf intel-pt: don't zero the whole perf_sample
Date: Sat, 11 Jan 2025 12:56:17 -0500 [thread overview]
Message-ID: <d841b97b3ad2ca8bcab07e4293375fb7c32dfce7.1736618095.git.tavianator@tavianator.com> (raw)
C designated initializers like
struct perf_sample sample = { .ip = 0, };
set every unmentioned field of the struct to zero. But since
sizeof(struct perf_sample) == 1384, this takes a long time.
struct perf_sample does not need to be fully initialized, and even
.ip = 0 is unnecessary because intel_pt_prep_*_sample() will initialize
it. Skipping the initialization saves about 2.5% of the execution time
when running
$ perf script --itrace=i0
Signed-off-by: Tavian Barnes <tavianator@tavianator.com>
---
tools/perf/util/intel-pt.c | 28 ++++++++++++++--------------
1 file changed, 14 insertions(+), 14 deletions(-)
diff --git a/tools/perf/util/intel-pt.c b/tools/perf/util/intel-pt.c
index 30be6dfe09eb..c829398c5bb9 100644
--- a/tools/perf/util/intel-pt.c
+++ b/tools/perf/util/intel-pt.c
@@ -1764,7 +1764,7 @@ static int intel_pt_synth_branch_sample(struct intel_pt_queue *ptq)
{
struct intel_pt *pt = ptq->pt;
union perf_event *event = ptq->event_buf;
- struct perf_sample sample = { .ip = 0, };
+ struct perf_sample sample;
struct dummy_branch_stack {
u64 nr;
u64 hw_idx;
@@ -1835,7 +1835,7 @@ static int intel_pt_synth_instruction_sample(struct intel_pt_queue *ptq)
{
struct intel_pt *pt = ptq->pt;
union perf_event *event = ptq->event_buf;
- struct perf_sample sample = { .ip = 0, };
+ struct perf_sample sample;
if (intel_pt_skip_event(pt))
return 0;
@@ -1867,7 +1867,7 @@ static int intel_pt_synth_cycle_sample(struct intel_pt_queue *ptq)
{
struct intel_pt *pt = ptq->pt;
union perf_event *event = ptq->event_buf;
- struct perf_sample sample = { .ip = 0, };
+ struct perf_sample sample;
u64 period = 0;
if (ptq->sample_ipc)
@@ -1894,7 +1894,7 @@ static int intel_pt_synth_transaction_sample(struct intel_pt_queue *ptq)
{
struct intel_pt *pt = ptq->pt;
union perf_event *event = ptq->event_buf;
- struct perf_sample sample = { .ip = 0, };
+ struct perf_sample sample;
if (intel_pt_skip_event(pt))
return 0;
@@ -1927,7 +1927,7 @@ static int intel_pt_synth_ptwrite_sample(struct intel_pt_queue *ptq)
{
struct intel_pt *pt = ptq->pt;
union perf_event *event = ptq->event_buf;
- struct perf_sample sample = { .ip = 0, };
+ struct perf_sample sample;
struct perf_synth_intel_ptwrite raw;
if (intel_pt_skip_event(pt))
@@ -1953,7 +1953,7 @@ static int intel_pt_synth_cbr_sample(struct intel_pt_queue *ptq)
{
struct intel_pt *pt = ptq->pt;
union perf_event *event = ptq->event_buf;
- struct perf_sample sample = { .ip = 0, };
+ struct perf_sample sample;
struct perf_synth_intel_cbr raw;
u32 flags;
@@ -1983,7 +1983,7 @@ static int intel_pt_synth_psb_sample(struct intel_pt_queue *ptq)
{
struct intel_pt *pt = ptq->pt;
union perf_event *event = ptq->event_buf;
- struct perf_sample sample = { .ip = 0, };
+ struct perf_sample sample;
struct perf_synth_intel_psb raw;
if (intel_pt_skip_event(pt))
@@ -2009,7 +2009,7 @@ static int intel_pt_synth_mwait_sample(struct intel_pt_queue *ptq)
{
struct intel_pt *pt = ptq->pt;
union perf_event *event = ptq->event_buf;
- struct perf_sample sample = { .ip = 0, };
+ struct perf_sample sample;
struct perf_synth_intel_mwait raw;
if (intel_pt_skip_event(pt))
@@ -2034,7 +2034,7 @@ static int intel_pt_synth_pwre_sample(struct intel_pt_queue *ptq)
{
struct intel_pt *pt = ptq->pt;
union perf_event *event = ptq->event_buf;
- struct perf_sample sample = { .ip = 0, };
+ struct perf_sample sample;
struct perf_synth_intel_pwre raw;
if (intel_pt_skip_event(pt))
@@ -2059,7 +2059,7 @@ static int intel_pt_synth_exstop_sample(struct intel_pt_queue *ptq)
{
struct intel_pt *pt = ptq->pt;
union perf_event *event = ptq->event_buf;
- struct perf_sample sample = { .ip = 0, };
+ struct perf_sample sample;
struct perf_synth_intel_exstop raw;
if (intel_pt_skip_event(pt))
@@ -2084,7 +2084,7 @@ static int intel_pt_synth_pwrx_sample(struct intel_pt_queue *ptq)
{
struct intel_pt *pt = ptq->pt;
union perf_event *event = ptq->event_buf;
- struct perf_sample sample = { .ip = 0, };
+ struct perf_sample sample;
struct perf_synth_intel_pwrx raw;
if (intel_pt_skip_event(pt))
@@ -2235,7 +2235,7 @@ static void intel_pt_add_lbrs(struct branch_stack *br_stack,
static int intel_pt_do_synth_pebs_sample(struct intel_pt_queue *ptq, struct evsel *evsel, u64 id)
{
const struct intel_pt_blk_items *items = &ptq->state->items;
- struct perf_sample sample = { .ip = 0, };
+ struct perf_sample sample;
union perf_event *event = ptq->event_buf;
struct intel_pt *pt = ptq->pt;
u64 sample_type = evsel->core.attr.sample_type;
@@ -2407,7 +2407,7 @@ static int intel_pt_synth_events_sample(struct intel_pt_queue *ptq)
{
struct intel_pt *pt = ptq->pt;
union perf_event *event = ptq->event_buf;
- struct perf_sample sample = { .ip = 0, };
+ struct perf_sample sample;
struct {
struct perf_synth_intel_evt cfe;
struct perf_synth_intel_evd evd[INTEL_PT_MAX_EVDS];
@@ -2446,7 +2446,7 @@ static int intel_pt_synth_iflag_chg_sample(struct intel_pt_queue *ptq)
{
struct intel_pt *pt = ptq->pt;
union perf_event *event = ptq->event_buf;
- struct perf_sample sample = { .ip = 0, };
+ struct perf_sample sample;
struct perf_synth_intel_iflag_chg raw;
if (intel_pt_skip_event(pt))
--
2.47.1
next reply other threads:[~2025-01-11 17:57 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-01-11 17:56 Tavian Barnes [this message]
2025-01-13 8:15 ` Adrian Hunter
2025-01-13 16:26 ` Tavian Barnes
2025-01-13 17:30 ` Ian Rogers
2025-01-13 19:45 ` Ian Rogers
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