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SubjectRe: [PATCH V6 6/8] perf/tools: Extend branch type classification
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On 6/14/22 22:23, German Gomez wrote:
> Hi Anshuman,
>
> On 10/06/2022 04:50, Anshuman Khandual wrote:
>> This updates the perf tool with generic branch type classification with new
>> ABI extender place holder i.e PERF_BR_EXTEND_ABI, the new 4 bit branch type
>> field i.e perf_branch_entry.new_type, new generic page fault related branch
>> types and some arch specific branch types as added earlier in the kernel.
>>
>> Cc: Peter Zijlstra <peterz@infradead.org>
>> Cc: Ingo Molnar <mingo@redhat.com>
>> Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
>> Cc: Mark Rutland <mark.rutland@arm.com>
>> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
>> Cc: Jiri Olsa <jolsa@redhat.com>
>> Cc: Namhyung Kim <namhyung@kernel.org>
>> Cc: Thomas Gleixner <tglx@linutronix.de>
>> Cc: Will Deacon <will@kernel.org>
>> Cc: linux-arm-kernel@lists.infradead.org
>> Cc: linux-perf-users@vger.kernel.org
>> Cc: linux-kernel@vger.kernel.org
>> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
>> ---
>> tools/include/uapi/linux/perf_event.h | 16 ++++++++-
>> tools/perf/builtin-script.c | 2 +-
>> tools/perf/util/branch.c | 52 ++++++++++++++++++++++++++-
>> tools/perf/util/branch.h | 6 +++-
>> tools/perf/util/session.c | 2 +-
>> 5 files changed, 73 insertions(+), 5 deletions(-)
>>
>> diff --git a/tools/include/uapi/linux/perf_event.h b/tools/include/uapi/linux/perf_event.h
>> index 26d8f0b5ac0d..d29280adc3c4 100644
>> --- a/tools/include/uapi/linux/perf_event.h
>> +++ b/tools/include/uapi/linux/perf_event.h
>> @@ -255,9 +255,22 @@ enum {
>> PERF_BR_IRQ = 12, /* irq */
>> PERF_BR_SERROR = 13, /* system error */
>> PERF_BR_NO_TX = 14, /* not in transaction */
>> + PERF_BR_EXTEND_ABI = 15, /* extend ABI */
>> PERF_BR_MAX,
>> };
>>
>> +enum {
>> + PERF_BR_NEW_FAULT_ALGN = 0, /* Alignment fault */
>> + PERF_BR_NEW_FAULT_DATA = 1, /* Data fault */
>> + PERF_BR_NEW_FAULT_INST = 2, /* Inst fault */
>> + PERF_BR_NEW_ARCH_1 = 3, /* Architecture specific */
>> + PERF_BR_NEW_ARCH_2 = 4, /* Architecture specific */
>> + PERF_BR_NEW_ARCH_3 = 5, /* Architecture specific */
>> + PERF_BR_NEW_ARCH_4 = 6, /* Architecture specific */
>> + PERF_BR_NEW_ARCH_5 = 7, /* Architecture specific */
>> + PERF_BR_NEW_MAX,
>> +};
>> +
>> #define PERF_SAMPLE_BRANCH_PLM_ALL \
>> (PERF_SAMPLE_BRANCH_USER|\
>> PERF_SAMPLE_BRANCH_KERNEL|\
>> @@ -1372,7 +1385,8 @@ struct perf_branch_entry {
>> abort:1, /* transaction abort */
>> cycles:16, /* cycle count to last branch */
>> type:4, /* branch type */
>> - reserved:40;
>> + new_type:4, /* additional branch type */
>> + reserved:36;
>> };
>>
>> union perf_sample_weight {
>> diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c
>> index c689054002cc..d4d581230f23 100644
>> --- a/tools/perf/builtin-script.c
>> +++ b/tools/perf/builtin-script.c
>> @@ -866,7 +866,7 @@ static int print_bstack_flags(FILE *fp, struct branch_entry *br)
>> br->flags.in_tx ? 'X' : '-',
>> br->flags.abort ? 'A' : '-',
>> br->flags.cycles,
>> - br->flags.type ? branch_type_name(br->flags.type) : "-");
>> + get_branch_type(br));
> (Small comment below regarding this line)
>
>> }
>>
>> static int perf_sample__fprintf_brstack(struct perf_sample *sample,
>> diff --git a/tools/perf/util/branch.c b/tools/perf/util/branch.c
>> index abc673347bee..6d962b0a4532 100644
>> --- a/tools/perf/util/branch.c
>> +++ b/tools/perf/util/branch.c
>> @@ -21,7 +21,10 @@ void branch_type_count(struct branch_type_stat *st, struct branch_flags *flags,
>> if (flags->type == PERF_BR_UNKNOWN || from == 0)
>> return;
>>
>> - st->counts[flags->type]++;
>> + if (flags->type == PERF_BR_EXTEND_ABI)
>> + st->new_counts[flags->new_type]++;
>> + else
>> + st->counts[flags->type]++;
>>
>> if (flags->type == PERF_BR_COND) {
>> if (to > from)
>> @@ -36,6 +39,25 @@ void branch_type_count(struct branch_type_stat *st, struct branch_flags *flags,
>> st->cross_4k++;
>> }
>>
>> +const char *branch_new_type_name(int new_type)
>> +{
>> + const char *branch_new_names[PERF_BR_NEW_MAX] = {
>> + "FAULT_ALGN",
>> + "FAULT_DATA",
>> + "FAULT_INST",
>> + "ARCH_1",
>> + "ARCH_2",
>> + "ARCH_3",
>> + "ARCH_4",
>> + "ARCH_5"
>> + };
>> +
>> + if (new_type >= 0 && new_type < PERF_BR_NEW_MAX)
>> + return branch_new_names[new_type];
>> +
>> + return NULL;
>> +}
>> +
>> const char *branch_type_name(int type)
>> {
>> const char *branch_names[PERF_BR_MAX] = {
>> @@ -62,6 +84,17 @@ const char *branch_type_name(int type)
>> return NULL;
>> }
>>
>> +const char *get_branch_type(struct branch_entry *e)
>> +{
>> + if (e->flags.type == PERF_BR_UNKNOWN)
>> + return "";
> There is a small change of behavior in "perf script --field brstack".
> Unknown branches were printed as "-" before but now it's an empty
> string.

get_branch_type() replaces print output in two different functions.
branch_stack__printf() used to print a space " " for PERF_BR_UNKNOWN,
and print_bstack_flags() used to print a "-" for PERF_BR_UNKNOWN.
When they are factorized via get_branch_type(), one of those print
formats need to be choosen.

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