Re: [PATCH] perf stat: Fix wrong skipping for per-die aggregation
From: Jin, Yao
Date: Wed Dec 23 2020 - 20:26:58 EST
On 12/24/2020 6:35 AM, Jiri Olsa wrote:
On Wed, Dec 16, 2020 at 03:01:46PM +0800, Jin Yao wrote:
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 a pair of die_id + socket_id to
decide if this cpu counts needs to skip. Only considering socket_id 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
1.001622560 S0-D0 1 1210176 Bytes llc_misses.mem_read
1.001622560 S0-D1 1 950208 Bytes llc_misses.mem_read
1.001622560 S1-D0 1 968704 Bytes llc_misses.mem_read
1.001622560 S1-D1 1 1113280 Bytes llc_misses.mem_read
2.004399430 S0-D0 1 1258560 Bytes llc_misses.mem_read
2.004399430 S0-D1 1 1011008 Bytes llc_misses.mem_read
2.004399430 S1-D0 1 1036544 Bytes llc_misses.mem_read
2.004399430 S1-D1 1 1237376 Bytes llc_misses.mem_read
3.006535657 S0-D0 1 1036608 Bytes llc_misses.mem_read
3.006535657 S0-D1 1 906560 Bytes llc_misses.mem_read
3.006535657 S1-D0 1 994112 Bytes llc_misses.mem_read
3.006535657 S1-D1 1 1025472 Bytes llc_misses.mem_read
4.008934402 S0-D0 1 1005120 Bytes llc_misses.mem_read
4.008934402 S0-D1 1 882368 Bytes llc_misses.mem_read
4.008934402 S1-D0 1 961408 Bytes llc_misses.mem_read
4.008934402 S1-D1 1 988352 Bytes llc_misses.mem_read
5.001605406 S0-D0 1 1930240 Bytes llc_misses.mem_read
5.001605406 S0-D1 1 1134272 Bytes llc_misses.mem_read
5.001605406 S1-D0 1 1531136 Bytes llc_misses.mem_read
5.001605406 S1-D1 1 2230848 Bytes llc_misses.mem_read
On no-die system, die_id is 0, this patch keeps original behavior unchanged.
Reported-by: Huang Ying <ying.huang@xxxxxxxxx>
Signed-off-by: Jin Yao <yao.jin@xxxxxxxxxxxxxxx>
---
tools/perf/util/cpumap.h | 2 ++
tools/perf/util/stat.c | 21 +++++++++++++++++----
2 files changed, 19 insertions(+), 4 deletions(-)
diff --git a/tools/perf/util/cpumap.h b/tools/perf/util/cpumap.h
index 3a442f021468..58604c047121 100644
--- a/tools/perf/util/cpumap.h
+++ b/tools/perf/util/cpumap.h
@@ -7,6 +7,8 @@
#include <internal/cpumap.h>
#include <perf/cpumap.h>
+#define CPU_MAP_MAX_DIE 256
+
struct perf_record_cpu_map_data;
struct perf_cpu_map *perf_cpu_map__empty_new(int nr);
diff --git a/tools/perf/util/stat.c b/tools/perf/util/stat.c
index 1e125e39ff84..b3fc6e261fe0 100644
--- a/tools/perf/util/stat.c
+++ b/tools/perf/util/stat.c
@@ -282,9 +282,9 @@ static void zero_per_pkg(struct evsel *counter)
static int check_per_pkg(struct evsel *counter,
struct perf_counts_values *vals, int cpu, bool *skip)
{
- unsigned long *mask = counter->per_pkg_mask;
+ unsigned long *mask = counter->per_pkg_mask, *l;
struct perf_cpu_map *cpus = evsel__cpus(counter);
- int s;
+ int s, d;
*skip = false;
@@ -295,7 +295,7 @@ static int check_per_pkg(struct evsel *counter,
return 0;
if (!mask) {
- mask = zalloc(cpu__max_cpu());
+ mask = zalloc(cpu__max_cpu() * CPU_MAP_MAX_DIE);
if (!mask)
return -ENOMEM;
@@ -317,7 +317,20 @@ static int check_per_pkg(struct evsel *counter,
if (s < 0)
return -1;
- *skip = test_and_set_bit(s, mask) == 1;
+ d = cpu_map__get_die(cpus, cpu, NULL);
+ if (d < 0)
+ return -1;
+
+ /*
+ * On multi-die system, die_id < 256. We use a pair
+ * of socket + die to identify the used bit.
+ * On no-die system, die_id is 0, l = &mask[0]. It doesn't
+ * change original "test_and_set_bit(s, mask)" behavior.
+ */
+ d &= 0xff;
+ l = &mask[d];
James is fixing the aggregation, because we could get large socket numbers:
https://lore.kernel.org/lkml/20201126141328.6509-1-james.clark@xxxxxxx/
James is using "struct cpu_aggr_map" to replace "struct perf_cpu_map", but do we also need to
replace the "struct perf_cpu_map" in "struct perf_evsel"? Otherwise the evsel->cpus will be
inconsistent, right?
struct perf_evsel {
...
struct perf_cpu_map *cpus;
struct perf_cpu_map *own_cpus;
...
};
I think we should fix that in here as well
Yes, we need to fix that in check_per_pkg() as well. As I said above, in check_per_pkg(),
struct perf_cpu_map *cpus = evsel__cpus(counter);
we should use "struct cpu_aggr_map" here.
maybe just use hashmap (socket,die) -> bool ?
Yes, hashmap should be better, saving more memory.
Thanks
Jin Yao
jirka
+
+ *skip = test_and_set_bit(s, l) == 1;
return 0;
}
--
2.17.1