Re: [PATCH 6/9] perf report: Support instruction latency

From: Liang, Kan
Date: Thu Feb 04 2021 - 10:24:12 EST

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On 2/4/2021 8:11 AM, Athira Rajeev wrote:

On 03-Feb-2021, at 1:39 AM, kan.liang@xxxxxxxxxxxxxxx wrote:

From: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>

The instruction latency information can be recorded on some platforms,
e.g., the Intel Sapphire Rapids server. With both memory latency
(weight) and the new instruction latency information, users can easily
locate the expensive load instructions, and also understand the time
spent in different stages. The users can optimize their applications
in different pipeline stages.

The 'weight' field is shared among different architectures. Reusing the
'weight' field may impacts other architectures. Add a new field to store
the instruction latency.

Like the 'weight' support, introduce a 'ins_lat' for the global
instruction latency, and a 'local_ins_lat' for the local instruction
latency version.

Add new sort functions, INSTR Latency and Local INSTR Latency,
accordingly.

Add local_ins_lat to the default_mem_sort_order[].

Signed-off-by: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>
---
tools/perf/Documentation/perf-report.txt | 6 +++-
tools/perf/util/event.h | 1 +
tools/perf/util/evsel.c | 4 ++-
tools/perf/util/hist.c | 12 ++++++--
tools/perf/util/hist.h | 2 ++
tools/perf/util/intel-pt.c | 5 ++--
tools/perf/util/session.c | 8 ++++--
tools/perf/util/sort.c | 47 +++++++++++++++++++++++++++++++-
tools/perf/util/sort.h | 3 ++
tools/perf/util/synthetic-events.c | 4 ++-
10 files changed, 81 insertions(+), 11 deletions(-)

diff --git a/tools/perf/Documentation/perf-report.txt b/tools/perf/Documentation/perf-report.txt
index 826b5a9..0565b7c 100644
--- a/tools/perf/Documentation/perf-report.txt
+++ b/tools/perf/Documentation/perf-report.txt
@@ -108,6 +108,9 @@ OPTIONS
- period: Raw number of event count of sample
- time: Separate the samples by time stamp with the resolution specified by
--time-quantum (default 100ms). Specify with overhead and before it.
+ - ins_lat: Instruction latency in core cycles. This is the global
+ instruction latency
+ - local_ins_lat: Local instruction latency version

By default, comm, dso and symbol keys are used.
(i.e. --sort comm,dso,symbol)
@@ -154,7 +157,8 @@ OPTIONS
- blocked: reason of blocked load access for the data at the time of the sample

And the default sort keys are changed to local_weight, mem, sym, dso,
- symbol_daddr, dso_daddr, snoop, tlb, locked, blocked, see '--mem-mode'.
+ symbol_daddr, dso_daddr, snoop, tlb, locked, blocked, local_ins_lat,
+ see '--mem-mode'.

If the data file has tracepoint event(s), following (dynamic) sort keys
are also available:
diff --git a/tools/perf/util/event.h b/tools/perf/util/event.h
index ff403ea..5d50a49 100644
--- a/tools/perf/util/event.h
+++ b/tools/perf/util/event.h
@@ -141,6 +141,7 @@ struct perf_sample {
u16 insn_len;
u8 cpumode;
u16 misc;
+ u16 ins_lat;
bool no_hw_idx; /* No hw_idx collected in branch_stack */
char insn[MAX_INSN];
void *raw_data;
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 0a2a307..24c0b59 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -2337,8 +2337,10 @@ int evsel__parse_sample(struct evsel *evsel, union perf_event *event,
weight.full = *array;
if (type & PERF_SAMPLE_WEIGHT)
data->weight = weight.full;
- else
+ else {
data->weight = weight.var1_dw;
+ data->ins_lat = weight.var2_w;
+ }
array++;
}

diff --git a/tools/perf/util/hist.c b/tools/perf/util/hist.c
index 6866ab0..8a432f8 100644
--- a/tools/perf/util/hist.c
+++ b/tools/perf/util/hist.c
@@ -209,6 +209,8 @@ void hists__calc_col_len(struct hists *hists, struct hist_entry *h)
hists__new_col_len(hists, HISTC_LOCAL_WEIGHT, 12);
hists__new_col_len(hists, HISTC_GLOBAL_WEIGHT, 12);
hists__new_col_len(hists, HISTC_MEM_BLOCKED, 10);
+ hists__new_col_len(hists, HISTC_LOCAL_INS_LAT, 13);
+ hists__new_col_len(hists, HISTC_GLOBAL_INS_LAT, 13);
if (symbol_conf.nanosecs)
hists__new_col_len(hists, HISTC_TIME, 16);
else
@@ -286,12 +288,13 @@ static long hist_time(unsigned long htime)
}

static void he_stat__add_period(struct he_stat *he_stat, u64 period,
- u64 weight)
+ u64 weight, u64 ins_lat)
{

he_stat->period += period;
he_stat->weight += weight;
he_stat->nr_events += 1;
+ he_stat->ins_lat += ins_lat;
}

static void he_stat__add_stat(struct he_stat *dest, struct he_stat *src)
@@ -303,6 +306,7 @@ static void he_stat__add_stat(struct he_stat *dest, struct he_stat *src)
dest->period_guest_us += src->period_guest_us;
dest->nr_events += src->nr_events;
dest->weight += src->weight;
+ dest->ins_lat += src->ins_lat;
}

static void he_stat__decay(struct he_stat *he_stat)
@@ -591,6 +595,7 @@ static struct hist_entry *hists__findnew_entry(struct hists *hists,
int64_t cmp;
u64 period = entry->stat.period;
u64 weight = entry->stat.weight;
+ u64 ins_lat = entry->stat.ins_lat;
bool leftmost = true;

p = &hists->entries_in->rb_root.rb_node;
@@ -609,11 +614,11 @@ static struct hist_entry *hists__findnew_entry(struct hists *hists,

if (!cmp) {
if (sample_self) {
- he_stat__add_period(&he->stat, period, weight);
+ he_stat__add_period(&he->stat, period, weight, ins_lat);
hist_entry__add_callchain_period(he, period);
}
if (symbol_conf.cumulate_callchain)
- he_stat__add_period(he->stat_acc, period, weight);
+ he_stat__add_period(he->stat_acc, period, weight, ins_lat);

/*
* This mem info was allocated from sample__resolve_mem
@@ -723,6 +728,7 @@ __hists__add_entry(struct hists *hists,
.nr_events = 1,
.period = sample->period,
.weight = sample->weight,
+ .ins_lat = sample->ins_lat,
},
.parent = sym_parent,
.filtered = symbol__parent_filter(sym_parent) | al->filtered,
diff --git a/tools/perf/util/hist.h b/tools/perf/util/hist.h
index 522486b..36bca33 100644
--- a/tools/perf/util/hist.h
+++ b/tools/perf/util/hist.h
@@ -72,6 +72,8 @@ enum hist_column {
HISTC_DSO_SIZE,
HISTC_SYMBOL_IPC,
HISTC_MEM_BLOCKED,
+ HISTC_LOCAL_INS_LAT,
+ HISTC_GLOBAL_INS_LAT,
HISTC_NR_COLS, /* Last entry */
};

diff --git a/tools/perf/util/intel-pt.c b/tools/perf/util/intel-pt.c
index a929f6d..c9477d0 100644
--- a/tools/perf/util/intel-pt.c
+++ b/tools/perf/util/intel-pt.c
@@ -1871,9 +1871,10 @@ static int intel_pt_synth_pebs_sample(struct intel_pt_queue *ptq)
* cycles. Use latency >> 32 to distinguish the
* different format of the mem access latency field.
*/
- if (weight > 0)
+ if (weight > 0) {
sample.weight = weight & 0xffff;
- else
+ sample.ins_lat = items->mem_access_latency & 0xffff;
+ } else
sample.weight = items->mem_access_latency;
}
if (!sample.weight && items->has_tsx_aux_info) {
diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index a35d8c2..330e591 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -1297,8 +1297,12 @@ static void dump_sample(struct evsel *evsel, union perf_event *event,
if (sample_type & PERF_SAMPLE_STACK_USER)
stack_user__printf(&sample->user_stack);

- if (sample_type & PERF_SAMPLE_WEIGHT_TYPE)
- printf("... weight: %" PRIu64 "\n", sample->weight);
+ if (sample_type & PERF_SAMPLE_WEIGHT_TYPE) {
+ printf("... weight: %" PRIu64 "", sample->weight);
+ if (sample_type & PERF_SAMPLE_WEIGHT_STRUCT)
+ printf(",0x%"PRIx16"", sample->ins_lat);
+ printf("\n");
+ }

if (sample_type & PERF_SAMPLE_DATA_SRC)
printf(" . data_src: 0x%"PRIx64"\n", sample->data_src);
diff --git a/tools/perf/util/sort.c b/tools/perf/util/sort.c
index 249a03c..e0529f2 100644
--- a/tools/perf/util/sort.c
+++ b/tools/perf/util/sort.c
@@ -36,7 +36,7 @@ const char default_parent_pattern[] = "^sys_|^do_page_fault";
const char *parent_pattern = default_parent_pattern;
const char *default_sort_order = "comm,dso,symbol";
const char default_branch_sort_order[] = "comm,dso_from,symbol_from,symbol_to,cycles";
-const char default_mem_sort_order[] = "local_weight,mem,sym,dso,symbol_daddr,dso_daddr,snoop,tlb,locked,blocked";
+const char default_mem_sort_order[] = "local_weight,mem,sym,dso,symbol_daddr,dso_daddr,snoop,tlb,locked,blocked,local_ins_lat";
const char default_top_sort_order[] = "dso,symbol";
const char default_diff_sort_order[] = "dso,symbol";
const char default_tracepoint_sort_order[] = "trace";
@@ -1365,6 +1365,49 @@ struct sort_entry sort_global_weight = {
.se_width_idx = HISTC_GLOBAL_WEIGHT,
};

+static u64 he_ins_lat(struct hist_entry *he)
+{
+ return he->stat.nr_events ? he->stat.ins_lat / he->stat.nr_events : 0;
+}
+
+static int64_t
+sort__local_ins_lat_cmp(struct hist_entry *left, struct hist_entry *right)
+{
+ return he_ins_lat(left) - he_ins_lat(right);
+}
+
+static int hist_entry__local_ins_lat_snprintf(struct hist_entry *he, char *bf,
+ size_t size, unsigned int width)
+{
+ return repsep_snprintf(bf, size, "%-*u", width, he_ins_lat(he));
+}
+
+struct sort_entry sort_local_ins_lat = {
+ .se_header = "Local INSTR Latency",
+ .se_cmp = sort__local_ins_lat_cmp,
+ .se_snprintf = hist_entry__local_ins_lat_snprintf,
+ .se_width_idx = HISTC_LOCAL_INS_LAT,
+};

Hi Kan Liang,

Currently with this changes, perf will display "Local INSTR Latency” for the new column in ‘perf mem report’

Can we make this header string to be Architecture Specific ?

I don't think current perf supports an arch specific header string. It sounds like a new feature. I think it's a good feature.

Besides the instruction latency, we also introduce a 'block' field for perf mem. I'm not sure if the field applies for PowerPC. You may want to check it as well.

Could you please propose a patch to implement the feature? I think we can have a further discussion based on it.

Because in other archs, the var2_w of ‘perf_sample_weight’ could be used to capture something else than the Local INSTR Latency.
Can we have some weak function to populate the header string ?

I agree that the var2_w has different meanings among architectures. We should not force it to data->ins_lat.

The patch as below should fix it. Does it work for you?

diff --git a/tools/perf/arch/x86/util/event.c b/tools/perf/arch/x86/util/event.c
index 047dc00..9b31734 100644
--- a/tools/perf/arch/x86/util/event.c
+++ b/tools/perf/arch/x86/util/event.c
@@ -75,3 +75,28 @@ int perf_event__synthesize_extra_kmaps(struct perf_tool *tool,
}

#endif
+
+void arch_perf_parse_sample_weight(struct perf_sample *data,
+ const __u64 *array, u64 type)
+{
+ union perf_sample_weight weight;
+
+ weight.full = *array;
+ if (type & PERF_SAMPLE_WEIGHT)
+ data->weight = weight.full;
+ else {
+ data->weight = weight.var1_dw;
+ data->ins_lat = weight.var2_w;
+ }
+}
+
+void arch_perf_synthesize_sample_weight(const struct perf_sample *data,
+ __u64 *array, u64 type)
+{
+ *array = data->weight;
+
+ if (type & PERF_SAMPLE_WEIGHT_STRUCT) {
+ *array &= 0xffffffff;
+ *array |= ((u64)data->ins_lat << 32);
+ }
+}
diff --git a/tools/perf/util/event.h b/tools/perf/util/event.h
index 60752e4..9f123aa 100644
--- a/tools/perf/util/event.h
+++ b/tools/perf/util/event.h
@@ -414,4 +414,7 @@ extern unsigned int proc_map_timeout;
#define PAGE_SIZE_NAME_LEN 32
char *get_page_size_name(u64 size, char *str);

+void arch_perf_parse_sample_weight(struct perf_sample *data, const __u64 *array, u64 type);
+void arch_perf_synthesize_sample_weight(const struct perf_sample *data, __u64 *array, u64 type);
+
#endif /* __PERF_RECORD_H */
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 30b5452..1da8903 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -2106,6 +2106,13 @@ perf_event__check_size(union perf_event *event, unsigned int sample_size)
return 0;
}

+void __weak arch_perf_parse_sample_weight(struct perf_sample *data,
+ const __u64 *array,
+ u64 type __maybe_unused)
+{
+ data->weight = *array;
+}
+
int evsel__parse_sample(struct evsel *evsel, union perf_event *event,
struct perf_sample *data)
{
@@ -2347,16 +2354,8 @@ int evsel__parse_sample(struct evsel *evsel, union perf_event *event,
}

if (type & PERF_SAMPLE_WEIGHT_TYPE) {
- union perf_sample_weight weight;
-
OVERFLOW_CHECK_u64(array);
- weight.full = *array;
- if (type & PERF_SAMPLE_WEIGHT)
- data->weight = weight.full;
- else {
- data->weight = weight.var1_dw;
- data->ins_lat = weight.var2_w;
- }
+ arch_perf_parse_sample_weight(data, array, type);
array++;
}

diff --git a/tools/perf/util/synthetic-events.c b/tools/perf/util/synthetic-events.c
index c6f9db3..412f4c3 100644
--- a/tools/perf/util/synthetic-events.c
+++ b/tools/perf/util/synthetic-events.c
@@ -1507,6 +1507,12 @@ size_t perf_event__sample_event_size(const struct perf_sample *sample, u64 type,
return result;
}

+void __weak arch_perf_synthesize_sample_weight(const struct perf_sample *data,
+ __u64 *array, u64 type __maybe_unused)
+{
+ *array = data->weight;
+}
+
int perf_event__synthesize_sample(union perf_event *event, u64 type, u64 read_format,
const struct perf_sample *sample)
{
@@ -1643,11 +1649,7 @@ int perf_event__synthesize_sample(union perf_event *event, u64 type, u64 read_fo
}

if (type & PERF_SAMPLE_WEIGHT_TYPE) {
- *array = sample->weight;
- if (type & PERF_SAMPLE_WEIGHT_STRUCT) {
- *array &= 0xffffffff;
- *array |= ((u64)sample->ins_lat << 32);
- }
+ arch_perf_synthesize_sample_weight(sample, array, type);
array++;
}

Thanks,
Kan

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