Re: [PATCH] perf env: Find correct branch counter info on hybrid

From: Liang, Kan
Date: Wed Sep 11 2024 - 12:01:03 EST

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On 2024-09-11 11:58 a.m., Arnaldo Carvalho de Melo wrote:
> On Wed, Sep 11, 2024 at 11:41:54AM -0400, Liang, Kan wrote:
>>
>>
>> On 2024-09-11 10:19 a.m., Arnaldo Carvalho de Melo wrote:
>>> On Mon, Sep 09, 2024 at 11:42:00AM -0700, kan.liang@xxxxxxxxxxxxxxx wrote:
>>>> From: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>
>>>>
>>>> No event is printed in the "Branch Counter" column on hybrid machines.
>>>>
>>>> For example,
>>>> $perf record -e "{cpu_core/branch-instructions/pp,cpu_core/branches/}:S"
>>>> -j any,counter
>>>> $perf report --total-cycles
>>>
>>> So I tried this on an Intel Hybrid system, I start the TUI, then try 'B'
>>> and, after applying your patch:
>>>
>>> 0.66% 67.8K 0.00% 75 ┌─Branch counter abbr list────────────┐ibc_write+18] libc.so.6
>>> 0.63% 65.4K 0.00% 106 [p│ │r_active+159] [kernel.kallsyms]
>>> 0.61% 63.2K 0.01% 175 [native_queued_spi│ The branch counter is not available.│in_lock_slowpath+528] [kernel.kallsyms]
>>> 0.57% 58.4K 0.00% 39 [syscall_ex│Press any key... │ser_mode+109] [kernel.kallsyms]
>>> 0.54% 55.6K 0.00% 1 [_IO_file_xsputn@@└─────────────────────────────────────┘BC_2.2.5+316] libc.so.6
>>>
>>> The perf.data was obtained from:
>>>
>>> root@number:~# perf record -e "{cpu_core/branch-instructions/pp,cpu_core/branches/}:S" -j any,counter find /
>>>
>>> And:
>>>
>>> root@number:~# perf evlist --group
>>> {cpu_core/branch-instructions/pp,cpu_core/branches/}
>>> dummy:u
>>> root@number:~#
>>>
>>> Only mishap above we discussed already, the missing :S, and then:
>>>
>>> root@number:~# perf evlist -v
>>> cpu_core/branch-instructions/pp: type: 4 (cpu_core), size: 136, config: 0xc4 (branch-instructions), { sample_period, sample_freq }: 4000, sample_type: IP|TID|TIME|READ|PERIOD|BRANCH_STACK|IDENTIFIER, read_format: ID|GROUP|LOST, disabled: 1, freq: 1, enable_on_exec: 1, precise_ip: 2, sample_id_all: 1, exclude_guest: 1, branch_sample_type: ANY
>>
>> For a hybrid client, the "Branch Counter" feature is only supported
>> starting from the just released Lunar Lake. Perf falls back to only
>> "ANY" on your Raptor Lake.
>>
>> The "The branch counter is not available" message is expected.
>>
>> Here is the perf evlist result from my Lunar Lake machine,
>>
>> #perf evlist -v
>> cpu_core/branch-instructions/pp: type: 4 (cpu_core), size: 136, config:
>> 0xc4 (branch-instructions), { sample_period, sample_freq }: 4000,
>> sample_type: IP|TID|TIME|READ|PERIOD|BRANCH_STACK|IDENTIFIER,
>> read_format: ID|GROUP|LOST, disabled: 1, freq: 1, enable_on_exec: 1,
>> precise_ip: 2, sample_id_all: 1, exclude_guest: 1, branch_sample_type:
>> ANY|COUNTERS
>
> So I'll just take the patch and add these explanations there, ok?
>

Sounds good. Thanks!

Kan

> - Arnaldo
>
>>
>> Thanks,
>> Kan
>>> cpu_core/branches/: type: 0 (PERF_TYPE_HARDWARE), size: 136, config: 0x400000004, sample_type: IP|TID|TIME|READ|PERIOD|BRANCH_STACK|IDENTIFIER, read_format: ID|GROUP|LOST, sample_id_all: 1, exclude_guest: 1, branch_sample_type: ANY
>>> dummy:u: type: 1 (software), size: 136, config: 0x9 (PERF_COUNT_SW_DUMMY), { sample_period, sample_freq }: 1, sample_type: IP|TID|TIME|IDENTIFIER, read_format: ID|LOST, inherit: 1, exclude_kernel: 1, exclude_hv: 1, mmap: 1, comm: 1, task: 1, sample_id_all: 1, exclude_guest: 1, mmap2: 1, comm_exec: 1, ksymbol: 1, bpf_event: 1
>>> root@number:~#
>>>
>>> Version: Intel(R) Core(TM) i7-14700K
>>> Voltage: 1.0 V
>>> External Clock: 100 MHz
>>> Max Speed: 8500 MHz
>>> Current Speed: 3400 MHz
>>> Status: Populated, Enabled
>>> Upgrade: Socket LGA1700
>>>
>>> What am I doing wrong not to get to see that "branch counter abbr list"
>>> info to then check before/after your patch?
>>>
>>> - Arnaldo
>>>
>>>> # Branch counter abbr list:
>>>> # cpu_core/branch-instructions/pp = A
>>>> # cpu_core/branches/ = B
>>>> # '-' No event occurs
>>>> # '+' Event occurrences may be lost due to branch counter saturated
>>>> #
>>>> # Sampled Cycles% Sampled Cycles Avg Cycles% Avg Cycles Branch Counter
>>>> # ............... .............. ........... .......... ..............
>>>> 44.54% 727.1K 0.00% 1 |+ |+ |
>>>> 36.31% 592.7K 0.00% 2 |+ |+ |
>>>> 17.83% 291.1K 0.00% 1 |+ |+ |
>>>>
>>>> The branch counter information (br_cntr_width and br_cntr_nr) in the
>>>> perf_env is retrieved from the CPU_PMU_CAPS. However, the CPU_PMU_CAPS
>>>> is not available on hybrid machines. Without the width information, the
>>>> number of occurrences of an event cannot be calculated.
>>>>
>>>> For a hybrid machine, the caps information should be retrieved from the
>>>> PMU_CAPS, and stored in the perf_env->pmu_caps.
>>>>
>>>> Add a perf_env__find_br_cntr_info() to return the correct branch counter
>>>> information from the corresponding fields.
>>>>
>>>> Fixes: 6f9d8d1de2c6 ("perf script: Add branch counters")
>>>> Signed-off-by: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>
>>>> ---
>>>> tools/perf/builtin-script.c | 5 +++--
>>>> tools/perf/util/annotate.c | 5 +++--
>>>> tools/perf/util/env.c | 15 +++++++++++++++
>>>> tools/perf/util/env.h | 3 +++
>>>> tools/perf/util/session.c | 6 ++++--
>>>> 5 files changed, 28 insertions(+), 6 deletions(-)
>>>>
>>>> diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c
>>>> index dbe792b52c5c..a644787fa9e1 100644
>>>> --- a/tools/perf/builtin-script.c
>>>> +++ b/tools/perf/builtin-script.c
>>>> @@ -1241,10 +1241,11 @@ static int ip__fprintf_jump(uint64_t ip, struct branch_entry *en,
>>>> }
>>>>
>>>> if (PRINT_FIELD(BRCNTR)) {
>>>> - unsigned int width = evsel__env(evsel)->br_cntr_width;
>>>> - unsigned int i = 0, j, num, mask = (1L << width) - 1;
>>>> struct evsel *pos = evsel__leader(evsel);
>>>> + unsigned int i = 0, j, num, mask, width;
>>>>
>>>> + perf_env__find_br_cntr_info(evsel__env(evsel), NULL, &width);
>>>> + mask = (1L << width) - 1;
>>>> printed += fprintf(fp, "br_cntr: ");
>>>> evlist__for_each_entry_from(evsel->evlist, pos) {
>>>> if (!(pos->core.attr.branch_sample_type & PERF_SAMPLE_BRANCH_COUNTERS))
>>>> diff --git a/tools/perf/util/annotate.c b/tools/perf/util/annotate.c
>>>> index 4990c70b1794..c6ebde9d40a8 100644
>>>> --- a/tools/perf/util/annotate.c
>>>> +++ b/tools/perf/util/annotate.c
>>>> @@ -333,14 +333,15 @@ static int symbol__account_br_cntr(struct annotated_branch *branch,
>>>> {
>>>> unsigned int br_cntr_nr = evsel__leader(evsel)->br_cntr_nr;
>>>> unsigned int base = evsel__leader(evsel)->br_cntr_idx;
>>>> - unsigned int width = evsel__env(evsel)->br_cntr_width;
>>>> unsigned int off = offset * evsel->evlist->nr_br_cntr;
>>>> - unsigned int i, mask = (1L << width) - 1;
>>>> u64 *branch_br_cntr = branch->br_cntr;
>>>> + unsigned int i, mask, width;
>>>>
>>>> if (!br_cntr || !branch_br_cntr)
>>>> return 0;
>>>>
>>>> + perf_env__find_br_cntr_info(evsel__env(evsel), NULL, &width);
>>>> + mask = (1L << width) - 1;
>>>> for (i = 0; i < br_cntr_nr; i++) {
>>>> u64 cntr = (br_cntr >> i * width) & mask;
>>>>
>>>> diff --git a/tools/perf/util/env.c b/tools/perf/util/env.c
>>>> index a459374d0a1a..1edbccfc3281 100644
>>>> --- a/tools/perf/util/env.c
>>>> +++ b/tools/perf/util/env.c
>>>> @@ -624,3 +624,18 @@ char *perf_env__find_pmu_cap(struct perf_env *env, const char *pmu_name,
>>>> free(cap_eq);
>>>> return NULL;
>>>> }
>>>> +
>>>> +void perf_env__find_br_cntr_info(struct perf_env *env,
>>>> + unsigned int *nr,
>>>> + unsigned int *width)
>>>> +{
>>>> + if (nr) {
>>>> + *nr = env->cpu_pmu_caps ? env->br_cntr_nr :
>>>> + env->pmu_caps->br_cntr_nr;
>>>> + }
>>>> +
>>>> + if (width) {
>>>> + *width = env->cpu_pmu_caps ? env->br_cntr_width :
>>>> + env->pmu_caps->br_cntr_width;
>>>> + }
>>>> +}
>>>> diff --git a/tools/perf/util/env.h b/tools/perf/util/env.h
>>>> index 2a2c37cc40b7..51b36c36019b 100644
>>>> --- a/tools/perf/util/env.h
>>>> +++ b/tools/perf/util/env.h
>>>> @@ -192,4 +192,7 @@ char *perf_env__find_pmu_cap(struct perf_env *env, const char *pmu_name,
>>>> const char *cap);
>>>>
>>>> bool perf_env__has_pmu_mapping(struct perf_env *env, const char *pmu_name);
>>>> +void perf_env__find_br_cntr_info(struct perf_env *env,
>>>> + unsigned int *nr,
>>>> + unsigned int *width);
>>>> #endif /* __PERF_ENV_H */
>>>> diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
>>>> index b492300ec959..dbaf07bf6c5f 100644
>>>> --- a/tools/perf/util/session.c
>>>> +++ b/tools/perf/util/session.c
>>>> @@ -856,7 +856,6 @@ static void branch_stack__printf(struct perf_sample *sample,
>>>> struct branch_entry *entries = perf_sample__branch_entries(sample);
>>>> bool callstack = evsel__has_branch_callstack(evsel);
>>>> u64 *branch_stack_cntr = sample->branch_stack_cntr;
>>>> - struct perf_env *env = evsel__env(evsel);
>>>> uint64_t i;
>>>>
>>>> if (!callstack) {
>>>> @@ -900,8 +899,11 @@ static void branch_stack__printf(struct perf_sample *sample,
>>>> }
>>>>
>>>> if (branch_stack_cntr) {
>>>> + unsigned int br_cntr_width, br_cntr_nr;
>>>> +
>>>> + perf_env__find_br_cntr_info(evsel__env(evsel), &br_cntr_nr, &br_cntr_width);
>>>> printf("... branch stack counters: nr:%" PRIu64 " (counter width: %u max counter nr:%u)\n",
>>>> - sample->branch_stack->nr, env->br_cntr_width, env->br_cntr_nr);
>>>> + sample->branch_stack->nr, br_cntr_width, br_cntr_nr);
>>>> for (i = 0; i < sample->branch_stack->nr; i++)
>>>> printf("..... %2"PRIu64": %016" PRIx64 "\n", i, branch_stack_cntr[i]);
>>>> }
>>>> --
>>>> 2.38.1
>>>

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