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Message-ID: <ZuGnCqBa4HZUzrmX@x1>
Date: Wed, 11 Sep 2024 11:19:54 -0300
From: Arnaldo Carvalho de Melo <acme@...nel.org>
To: kan.liang@...ux.intel.com
Cc: namhyung@...nel.org, irogers@...gle.com, jolsa@...nel.org,
	adrian.hunter@...el.com, linux-perf-users@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] perf env: Find correct branch counter info on hybrid

On Mon, Sep 09, 2024 at 11:42:00AM -0700, kan.liang@...ux.intel.com wrote:
> From: Kan Liang <kan.liang@...ux.intel.com>
> 
> 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@...ber:~# perf record -e "{cpu_core/branch-instructions/pp,cpu_core/branches/}:S" -j any,counter find /

And:

root@...ber:~# perf evlist --group 
{cpu_core/branch-instructions/pp,cpu_core/branches/}
dummy:u
root@...ber:~# 

Only mishap above we discussed already, the missing :S, and then:

root@...ber:~# 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
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@...ber:~#

        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@...ux.intel.com>
> ---
>  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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