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Date: Thu, 1 Sep 2022 10:37:24 +0530
From: Anshuman Khandual <anshuman.khandual@....com>
To: Arnaldo Carvalho de Melo <acme@...nel.org>
Cc: linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
peterz@...radead.org, alexander.shishkin@...ux.intel.com,
jolsa@...hat.com, mark.rutland@....com,
Robin Murphy <robin.murphy@....com>,
Suzuki Poulose <suzuki.poulose@....com>,
James Clark <james.clark@....com>,
Ingo Molnar <mingo@...hat.com>,
Namhyung Kim <namhyung@...nel.org>,
Thomas Gleixner <tglx@...utronix.de>,
Will Deacon <will@...nel.org>,
Catalin Marinas <catalin.marinas@....com>,
linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH V7 6/8] perf/tools: Extend branch type classification
On 8/31/22 02:41, Arnaldo Carvalho de Melo wrote:
> Em Wed, Aug 24, 2022 at 10:18:20AM +0530, Anshuman Khandual escreveu:
>> 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@...radead.org>
>> Cc: Ingo Molnar <mingo@...hat.com>
>> Cc: Arnaldo Carvalho de Melo <acme@...nel.org>
>> Cc: Mark Rutland <mark.rutland@....com>
>> Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
>> Cc: Jiri Olsa <jolsa@...hat.com>
>> Cc: Namhyung Kim <namhyung@...nel.org>
>> Cc: Thomas Gleixner <tglx@...utronix.de>
>> Cc: Will Deacon <will@...nel.org>
>> Cc: linux-arm-kernel@...ts.infradead.org
>> Cc: linux-perf-users@...r.kernel.org
>> Cc: linux-kernel@...r.kernel.org
>> Signed-off-by: Anshuman Khandual <anshuman.khandual@....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 146c137ff0c1..0f7c7ce29899 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|\
>> @@ -1375,7 +1388,8 @@ 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 13580a9c50b8..585171479876 100644
>> --- a/tools/perf/builtin-script.c
>> +++ b/tools/perf/builtin-script.c
>> @@ -877,7 +877,7 @@ 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));
>> }
>>
>> 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 "";
>> +
>> + if (e->flags.type == PERF_BR_EXTEND_ABI)
>> + return branch_new_type_name(e->flags.new_type);
>> +
>> + return branch_type_name(e->flags.type);
>> +}
>> +
>> void branch_type_stat_display(FILE *fp, struct branch_type_stat *st)
>> {
>> u64 total = 0;
>> @@ -108,6 +141,15 @@ void branch_type_stat_display(FILE *fp, struct branch_type_stat *st)
>> 100.0 *
>> (double)st->counts[i] / (double)total);
>> }
>> +
>> + for (i = 0; i < PERF_BR_NEW_MAX; i++) {
>> + if (st->new_counts[i] > 0)
>> + fprintf(fp, "\n%8s: %5.1f%%",
>> + branch_new_type_name(i),
>> + 100.0 *
>> + (double)st->new_counts[i] / (double)total);
>> + }
>> +
> Strange:
>
> 75 8.89 ubuntu:20.04-x-powerpc64el : FAIL gcc version 10.3.0 (Ubuntu 10.3.0-1ubuntu1~20.04)
> inlined from 'branch_type_stat_display' at util/branch.c:152:4:
> /usr/powerpc64le-linux-gnu/include/bits/stdio2.h:100:10: error: '%8s' directive argument is null [-Werror=format-overflow=]
> 100 | return __fprintf_chk (__stream, __USE_FORTIFY_LEVEL - 1, __fmt,
> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 101 | __va_arg_pack ());
> | ~~~~~~~~~~~~~~~~~
>
Indeed. But this new code block here looks exact same like the previous and existing one
i.e with branch_new_name() and PERF_BR_NEW_MAX. The complain is that - '%8s' directive
argument is NULL. This warning might just be a false positive [1], because of a compiler
problem on powerpc64el ? But please do let me know if something needs to be changed here
to avoid this warning.
[1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90036
- Anshuman
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