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SubjectRe: [PATCH v4] perf stat: Fix wrong skipping for per-die aggregation
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Hi Jiri,

On 1/12/2021 6:04 PM, Jiri Olsa wrote:
> On Tue, Jan 05, 2021 at 10:36:15AM +0800, Jin Yao wrote:
>
> SNIP
>
>> diff --git a/tools/perf/util/stat.c b/tools/perf/util/stat.c
>> index 8ce1479c98f0..a658e0ffaf2a 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)
>> @@ -276,15 +277,29 @@ void evlist__save_aggr_prev_raw_counts(struct evlist *evlist)
>> static void zero_per_pkg(struct evsel *counter)
>> {
>> if (counter->per_pkg_mask)
>> - memset(counter->per_pkg_mask, 0, cpu__max_cpu());
>> + hashmap__clear(counter->per_pkg_mask);
>> +}
>> +
>> +static size_t pkg_id_hash(const void *key, void *ctx __maybe_unused)
>> +{
>> + int socket = (int64_t)key >> 32;
>> +
>> + return socket;
>
> could be just simple return right, why the variable?
>

Sure, just simple return should be OK.

>> +}
>> +
>> +static bool pkg_id_equal(const void *key1, const void *key2,
>> + void *ctx __maybe_unused)
>> +{
>> + return (int64_t)key1 == (int64_t)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;
>> + uint64_t key;
>>
>> *skip = false;
>>
>> @@ -295,7 +310,7 @@ 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;
>>
>> @@ -317,7 +332,23 @@ static int check_per_pkg(struct evsel *counter,
>> if (s < 0)
>> return -1;
>>
>> - *skip = test_and_set_bit(s, mask) == 1;
>> + /*
>> + * On multi-die system, 0 < die_id < 256. 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 = (uint64_t)s << 32 | (d & 0xff);
>
> why the masking for d? also I thought it could be bigger than 256
>

I remember in previous perf tool it would show a warning "The die id number is too big" if die_id >
256 and cpu_map__get_die() returned -1. See commit db5742b6849e ("perf stat: Support per-die
aggregation").

But now the die_id checking is removed.

> would it better to do it the other way around?
>
> die << 32 | socket
>

I think this way is OK, thanks! I will use it in v5.

>
>> + if (hashmap__find(mask, (void *)key, NULL)) {
>> + *skip = true;
>> + } else {
>> + ret = hashmap__add(mask, (void *)key, (void *)1);
>> + if (ret)
>> + return -1;
>
> you could 'return ret' at the end and skip this extra check
>

Yes, define int ret = 0 and just 'return ret' at the end of function.

Thanks
Jin Yao

> thanks,
> jirka
>
>> + }
>> +
>> return 0;
>> }
>>
>> --
>> 2.17.1
>>
>

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