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Subject[PATCH v9] perf stat: Fix wrong skipping for per-die aggregation
Date
Uncore becomes die-scope on Xeon Cascade Lake-AP and perf has supported
--per-die aggregation yet.

One issue is found in check_per_pkg() for uncore events running on
AP system. On cascade Lake-AP, we have:

S0-D0
S0-D1
S1-D0
S1-D1

But in check_per_pkg(), S0-D1 and S1-D1 are skipped because the
mask bits for S0 and S1 have been set for S0-D0 and S1-D0. It doesn't
check die_id. So the counting for S0-D1 and S1-D1 are set to zero.
That's not correct.

root@lkp-csl-2ap4 ~# ./perf stat -a -I 1000 -e llc_misses.mem_read --per-die -- sleep 5
1.001460963 S0-D0 1 1317376 Bytes llc_misses.mem_read
1.001460963 S0-D1 1 998016 Bytes llc_misses.mem_read
1.001460963 S1-D0 1 970496 Bytes llc_misses.mem_read
1.001460963 S1-D1 1 1291264 Bytes llc_misses.mem_read
2.003488021 S0-D0 1 1082048 Bytes llc_misses.mem_read
2.003488021 S0-D1 1 1919040 Bytes llc_misses.mem_read
2.003488021 S1-D0 1 890752 Bytes llc_misses.mem_read
2.003488021 S1-D1 1 2380800 Bytes llc_misses.mem_read
3.005613270 S0-D0 1 1126080 Bytes llc_misses.mem_read
3.005613270 S0-D1 1 2898176 Bytes llc_misses.mem_read
3.005613270 S1-D0 1 870912 Bytes llc_misses.mem_read
3.005613270 S1-D1 1 3388608 Bytes llc_misses.mem_read
4.007627598 S0-D0 1 1124608 Bytes llc_misses.mem_read
4.007627598 S0-D1 1 3884416 Bytes llc_misses.mem_read
4.007627598 S1-D0 1 921088 Bytes llc_misses.mem_read
4.007627598 S1-D1 1 4451840 Bytes llc_misses.mem_read
5.001479927 S0-D0 1 963328 Bytes llc_misses.mem_read
5.001479927 S0-D1 1 4831936 Bytes llc_misses.mem_read
5.001479927 S1-D0 1 895104 Bytes llc_misses.mem_read
5.001479927 S1-D1 1 5496640 Bytes llc_misses.mem_read

From above output, we can see S0-D1 and S1-D1 don't report the interval
values, they are continued to grow. That's because check_per_pkg() wrongly
decides to use zero counts for S0-D1 and S1-D1.

So in check_per_pkg(), we should use hashmap(socket,die) to decide if
the cpu counts needs to skip. Only considering socket is not enough.

Now with this patch,

root@lkp-csl-2ap4 ~# ./perf stat -a -I 1000 -e llc_misses.mem_read --per-die -- sleep 5
1.001586691 S0-D0 1 1229440 Bytes llc_misses.mem_read
1.001586691 S0-D1 1 976832 Bytes llc_misses.mem_read
1.001586691 S1-D0 1 938304 Bytes llc_misses.mem_read
1.001586691 S1-D1 1 1227328 Bytes llc_misses.mem_read
2.003776312 S0-D0 1 1586752 Bytes llc_misses.mem_read
2.003776312 S0-D1 1 875392 Bytes llc_misses.mem_read
2.003776312 S1-D0 1 855616 Bytes llc_misses.mem_read
2.003776312 S1-D1 1 949376 Bytes llc_misses.mem_read
3.006512788 S0-D0 1 1338880 Bytes llc_misses.mem_read
3.006512788 S0-D1 1 920064 Bytes llc_misses.mem_read
3.006512788 S1-D0 1 877184 Bytes llc_misses.mem_read
3.006512788 S1-D1 1 1020736 Bytes llc_misses.mem_read
4.008895291 S0-D0 1 926592 Bytes llc_misses.mem_read
4.008895291 S0-D1 1 906368 Bytes llc_misses.mem_read
4.008895291 S1-D0 1 892224 Bytes llc_misses.mem_read
4.008895291 S1-D1 1 987712 Bytes llc_misses.mem_read
5.001590993 S0-D0 1 962624 Bytes llc_misses.mem_read
5.001590993 S0-D1 1 912512 Bytes llc_misses.mem_read
5.001590993 S1-D0 1 891200 Bytes llc_misses.mem_read
5.001590993 S1-D1 1 978432 Bytes llc_misses.mem_read

On no-die system, die_id is 0, actually it's hashmap(socket,0), original behavior
is not changed.

Reported-by: Huang Ying <ying.huang@intel.com>
Signed-off-by: Jin Yao <yao.jin@linux.intel.com>
---
v9:
Rename zero_per_pkg to evsel__zero_per_pkg and move it to evsel.c. Then
evsel__zero_per_pkg can be called under different code path.

Call evsel__zero_per_pkg in evsel__exit().

v8:
Jiri contributes idea and code to allocate 'uint64_t' type hash key for better
supporting for 64 bits platform and 32 bits platform. I merge Jiri's code in this
patch. Thanks Jiri!

Rebase the patch to latest perf/core branch.

v7:
It reported build error on 32-bit system (such as cross build by mipsel-linux-gnu-gcc).

In v7,
1. Use size_t to replace uint64_t.
2. The hash key is changed from 'die_id << 32 | socket_id' to 'die_id << 16 | socket_id',
16 bits is enough for socket id , right?

v6:
Fix the perf test python failure by adding hashmap.c to python-ext-sources.

root@kbl-ppc:~# ./perf test python
19: 'import perf' in python : Ok

v5:
Hash key is changed to die_id << 32 | socket.
In pkg_id_hash, return (int64_t)key & 0xffffffff; actually it's socket.

v4:
v3 used unnecessary bool allocatioin. v4 just uses the hash value '(void *)1'.

v4 is compiled ok with tmp.perf/core.

v3:
Since for some cpumap functions, the return type is changed from 'int' to
'struct aggr_cpu_id', the patch needs to be updated as well.

before:
d = cpu_map__get_die()

after:
d = cpu_map__get_die().die

v3 is compiled ok with tmp.perf/core.

v2:
Use hashmap to check the used socket+die pair.

tools/perf/util/evsel.c | 18 +++++++++++-
tools/perf/util/evsel.h | 4 ++-
tools/perf/util/python-ext-sources | 1 +
tools/perf/util/stat.c | 47 ++++++++++++++++++++++++------
4 files changed, 59 insertions(+), 11 deletions(-)

diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 8b18ec56e266..a8799bfa9fa7 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -46,6 +46,7 @@
#include "string2.h"
#include "memswap.h"
#include "util.h"
+#include "hashmap.h"
#include "../perf-sys.h"
#include "util/parse-branch-options.h"
#include <internal/xyarray.h>
@@ -1385,7 +1386,9 @@ void evsel__exit(struct evsel *evsel)
zfree(&evsel->group_name);
zfree(&evsel->name);
zfree(&evsel->pmu_name);
- zfree(&evsel->per_pkg_mask);
+ evsel__zero_per_pkg(evsel);
+ hashmap__free(evsel->per_pkg_mask);
+ evsel->per_pkg_mask = NULL;
zfree(&evsel->metric_events);
perf_evsel__object.fini(evsel);
}
@@ -2757,3 +2760,16 @@ int evsel__store_ids(struct evsel *evsel, struct evlist *evlist)

return store_evsel_ids(evsel, evlist);
}
+
+void evsel__zero_per_pkg(struct evsel *evsel)
+{
+ struct hashmap_entry *cur;
+ size_t bkt;
+
+ if (evsel->per_pkg_mask) {
+ hashmap__for_each_entry(evsel->per_pkg_mask, cur, bkt)
+ free((char *)cur->key);
+
+ hashmap__clear(evsel->per_pkg_mask);
+ }
+}
diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
index e25594494cf6..ede7c54ddc9c 100644
--- a/tools/perf/util/evsel.h
+++ b/tools/perf/util/evsel.h
@@ -19,6 +19,7 @@ struct perf_stat_evsel;
union perf_event;
struct bpf_counter_ops;
struct target;
+struct hashmap;

typedef int (evsel__sb_cb_t)(union perf_event *event, void *data);

@@ -112,7 +113,7 @@ struct evsel {
bool merged_stat;
bool reset_group;
bool errored;
- unsigned long *per_pkg_mask;
+ struct hashmap *per_pkg_mask;
struct evsel *leader;
struct list_head config_terms;
int err;
@@ -430,4 +431,5 @@ struct perf_env *evsel__env(struct evsel *evsel);

int evsel__store_ids(struct evsel *evsel, struct evlist *evlist);

+void evsel__zero_per_pkg(struct evsel *evsel);
#endif /* __PERF_EVSEL_H */
diff --git a/tools/perf/util/python-ext-sources b/tools/perf/util/python-ext-sources
index 71b753523fac..845dd46e3c61 100644
--- a/tools/perf/util/python-ext-sources
+++ b/tools/perf/util/python-ext-sources
@@ -36,3 +36,4 @@ util/symbol_fprintf.c
util/units.c
util/affinity.c
util/rwsem.c
+util/hashmap.c
diff --git a/tools/perf/util/stat.c b/tools/perf/util/stat.c
index 0b3957323f66..a6f1fed995b5 100644
--- a/tools/perf/util/stat.c
+++ b/tools/perf/util/stat.c
@@ -13,6 +13,7 @@
#include "evlist.h"
#include "evsel.h"
#include "thread_map.h"
+#include "hashmap.h"
#include <linux/zalloc.h>

void update_stats(struct stats *stats, u64 val)
@@ -273,18 +274,29 @@ void evlist__save_aggr_prev_raw_counts(struct evlist *evlist)
}
}

-static void zero_per_pkg(struct evsel *counter)
+static size_t pkg_id_hash(const void *__key, void *ctx __maybe_unused)
{
- if (counter->per_pkg_mask)
- memset(counter->per_pkg_mask, 0, cpu__max_cpu());
+ uint64_t *key = (uint64_t *) __key;
+
+ return *key & 0xffffffff;
+}
+
+static bool pkg_id_equal(const void *__key1, const void *__key2,
+ void *ctx __maybe_unused)
+{
+ uint64_t *key1 = (uint64_t *) __key1;
+ uint64_t *key2 = (uint64_t *) __key2;
+
+ return *key1 == *key2;
}

static int check_per_pkg(struct evsel *counter,
struct perf_counts_values *vals, int cpu, bool *skip)
{
- unsigned long *mask = counter->per_pkg_mask;
+ struct hashmap *mask = counter->per_pkg_mask;
struct perf_cpu_map *cpus = evsel__cpus(counter);
- int s;
+ int s, d, ret = 0;
+ uint64_t *key;

*skip = false;

@@ -295,7 +307,7 @@ static int check_per_pkg(struct evsel *counter,
return 0;

if (!mask) {
- mask = zalloc(cpu__max_cpu());
+ mask = hashmap__new(pkg_id_hash, pkg_id_equal, NULL);
if (!mask)
return -ENOMEM;

@@ -317,8 +329,25 @@ static int check_per_pkg(struct evsel *counter,
if (s < 0)
return -1;

- *skip = test_and_set_bit(s, mask) == 1;
- return 0;
+ /*
+ * On multi-die system, die_id > 0. On no-die system, die_id = 0.
+ * We use hashmap(socket, die) to check the used socket+die pair.
+ */
+ d = cpu_map__get_die(cpus, cpu, NULL).die;
+ if (d < 0)
+ return -1;
+
+ key = malloc(sizeof(*key));
+ if (!key)
+ return -ENOMEM;
+
+ *key = (uint64_t)d << 32 | s;
+ if (hashmap__find(mask, (void *)key, NULL))
+ *skip = true;
+ else
+ ret = hashmap__add(mask, (void *)key, (void *)1);
+
+ return ret;
}

static int
@@ -418,7 +447,7 @@ int perf_stat_process_counter(struct perf_stat_config *config,
}

if (counter->per_pkg)
- zero_per_pkg(counter);
+ evsel__zero_per_pkg(counter);

ret = process_counter_maps(config, counter);
if (ret)
--
2.17.1
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