Re: [PATCH v2 3/4] perf tools: Add printing perf_event_attr type symbol in perf_event_attr__fprintf()

From: Adrian Hunter
Date: Fri May 12 2023 - 06:35:11 EST


On 11/05/23 10:51, Yang Jihong wrote:
> When printing perf_event_attr, always display perf_event_attr type and its symbol
> to improve the readability of debugging information.
>
> Before:
>
> # perf --debug verbose=2 record -e cycles,cpu-clock,sched:sched_switch,branch-load-misses,r101,mem:0x0 -C 0 true
> <SNIP>
> ------------------------------------------------------------
> perf_event_attr:
> size 136
> { sample_period, sample_freq } 4000
> sample_type IP|TID|TIME|CPU|PERIOD|IDENTIFIER
> read_format ID
> disabled 1
> inherit 1
> freq 1
> sample_id_all 1
> exclude_guest 1
> ------------------------------------------------------------
> sys_perf_event_open: pid -1 cpu 0 group_fd -1 flags 0x8 = 5
> ------------------------------------------------------------
> perf_event_attr:
> type 1
> size 136
> { sample_period, sample_freq } 4000
> sample_type IP|TID|TIME|CPU|PERIOD|IDENTIFIER
> read_format ID
> disabled 1
> inherit 1
> freq 1
> sample_id_all 1
> exclude_guest 1
> ------------------------------------------------------------
> sys_perf_event_open: pid -1 cpu 0 group_fd -1 flags 0x8 = 6
> ------------------------------------------------------------
> perf_event_attr:
> type 2
> size 136
> config 0x143
> { sample_period, sample_freq } 1
> sample_type IP|TID|TIME|CPU|PERIOD|RAW|IDENTIFIER
> read_format ID
> disabled 1
> inherit 1
> sample_id_all 1
> exclude_guest 1
> ------------------------------------------------------------
> sys_perf_event_open: pid -1 cpu 0 group_fd -1 flags 0x8 = 7
> ------------------------------------------------------------
> perf_event_attr:
> type 3
> size 136
> config 0x10005
> { sample_period, sample_freq } 4000
> sample_type IP|TID|TIME|CPU|PERIOD|IDENTIFIER
> read_format ID
> disabled 1
> inherit 1
> freq 1
> sample_id_all 1
> exclude_guest 1
> ------------------------------------------------------------
> sys_perf_event_open: pid -1 cpu 0 group_fd -1 flags 0x8 = 9
> ------------------------------------------------------------
> perf_event_attr:
> type 4
> size 136
> config 0x101
> { sample_period, sample_freq } 4000
> sample_type IP|TID|TIME|CPU|PERIOD|IDENTIFIER
> read_format ID
> disabled 1
> inherit 1
> freq 1
> sample_id_all 1
> exclude_guest 1
> ------------------------------------------------------------
> sys_perf_event_open: pid -1 cpu 0 group_fd -1 flags 0x8 = 10
> ------------------------------------------------------------
> perf_event_attr:
> type 5
> size 136
> { sample_period, sample_freq } 1
> sample_type IP|TID|TIME|CPU|IDENTIFIER
> read_format ID
> disabled 1
> inherit 1
> sample_id_all 1
> exclude_guest 1
> bp_type 3
> { bp_len, config2 } 0x4
> ------------------------------------------------------------
> <SNIP>
>
> After:
>
> # perf --debug verbose=2 record -e cycles,cpu-clock,sched:sched_switch,branch-load-misses,r101,mem:0x0 -C 0 true
> <SNIP>
> ------------------------------------------------------------
> perf_event_attr:
> type 0 (PERF_TYPE_HARDWARE)
> size 136
> { sample_period, sample_freq } 4000
> sample_type IP|TID|TIME|CPU|PERIOD|IDENTIFIER
> read_format ID
> disabled 1
> inherit 1
> freq 1
> sample_id_all 1
> exclude_guest 1
> ------------------------------------------------------------
> sys_perf_event_open: pid -1 cpu 0 group_fd -1 flags 0x8 = 5
> ------------------------------------------------------------
> perf_event_attr:
> type 1 (PERF_TYPE_SOFTWARE)
> size 136
> { sample_period, sample_freq } 4000
> sample_type IP|TID|TIME|CPU|PERIOD|IDENTIFIER
> read_format ID
> disabled 1
> inherit 1
> freq 1
> sample_id_all 1
> exclude_guest 1
> ------------------------------------------------------------
> sys_perf_event_open: pid -1 cpu 0 group_fd -1 flags 0x8 = 6
> ------------------------------------------------------------
> perf_event_attr:
> type 2 (PERF_TYPE_TRACEPOINT)
> size 136
> config 0x143
> { sample_period, sample_freq } 1
> sample_type IP|TID|TIME|CPU|PERIOD|RAW|IDENTIFIER
> read_format ID
> disabled 1
> inherit 1
> sample_id_all 1
> exclude_guest 1
> ------------------------------------------------------------
> sys_perf_event_open: pid -1 cpu 0 group_fd -1 flags 0x8 = 7
> ------------------------------------------------------------
> perf_event_attr:
> type 3 (PERF_TYPE_HW_CACHE)
> size 136
> config 0x10005
> { sample_period, sample_freq } 4000
> sample_type IP|TID|TIME|CPU|PERIOD|IDENTIFIER
> read_format ID
> disabled 1
> inherit 1
> freq 1
> sample_id_all 1
> exclude_guest 1
> ------------------------------------------------------------
> sys_perf_event_open: pid -1 cpu 0 group_fd -1 flags 0x8 = 9
> ------------------------------------------------------------
> perf_event_attr:
> type 4 (PERF_TYPE_RAW)
> size 136
> config 0x101
> { sample_period, sample_freq } 4000
> sample_type IP|TID|TIME|CPU|PERIOD|IDENTIFIER
> read_format ID
> disabled 1
> inherit 1
> freq 1
> sample_id_all 1
> exclude_guest 1
> ------------------------------------------------------------
> sys_perf_event_open: pid -1 cpu 0 group_fd -1 flags 0x8 = 10
> ------------------------------------------------------------
> perf_event_attr:
> type 5 (PERF_TYPE_BREAKPOINT)
> size 136
> { sample_period, sample_freq } 1
> sample_type IP|TID|TIME|CPU|IDENTIFIER
> read_format ID
> disabled 1
> inherit 1
> sample_id_all 1
> exclude_guest 1
> bp_type 3
> { bp_len, config2 } 0x4
> ------------------------------------------------------------
> <SNIP>
>
> Signed-off-by: Yang Jihong <yangjihong1@xxxxxxxxxx>
> ---
> tools/perf/util/perf_event_attr_fprintf.c | 30 ++++++++++++++++++++++-
> 1 file changed, 29 insertions(+), 1 deletion(-)
>
> diff --git a/tools/perf/util/perf_event_attr_fprintf.c b/tools/perf/util/perf_event_attr_fprintf.c
> index 433029c6afc5..cd0905d8cb7a 100644
> --- a/tools/perf/util/perf_event_attr_fprintf.c
> +++ b/tools/perf/util/perf_event_attr_fprintf.c
> @@ -71,6 +71,33 @@ static void __p_read_format(char *buf, size_t size, u64 value)
> __p_bits(buf, size, value, bits);
> }
>
> +#define ENUM_ID_TO_STR_CASE(x) case x: return (#x);
> +static const char *stringify_perf_type_id(u64 value)
> +{
> + /* sync with enum perf_type_id in perf_event.h */

Everything in this file syncs with perf_event.h, so the comment
does not seem very useful.

> + switch (value) {
> + ENUM_ID_TO_STR_CASE(PERF_TYPE_HARDWARE)
> + ENUM_ID_TO_STR_CASE(PERF_TYPE_SOFTWARE)
> + ENUM_ID_TO_STR_CASE(PERF_TYPE_TRACEPOINT)
> + ENUM_ID_TO_STR_CASE(PERF_TYPE_HW_CACHE)
> + ENUM_ID_TO_STR_CASE(PERF_TYPE_RAW)
> + ENUM_ID_TO_STR_CASE(PERF_TYPE_BREAKPOINT)
> + default:
> + return NULL;
> + }
> +}
> +#undef ENUM_ID_TO_STR_CASE
> +
> +static void __p_type_id(char *buf, size_t size, u64 value)
> +{
> + const char *str = stringify_perf_type_id(value);
> +
> + if (str == NULL)
> + snprintf(buf, size, "%"PRIu64, value);
> + else
> + snprintf(buf, size, "%"PRIu64" (%s)", value, str);

These 4 lines end up getting used again about 3 times in the next
patch, so might as well be a separate function e.g.

print_id(buf, size, value, stringify_perf_type_id(value));

where:

static void print_id(char *buf, size_t size, u64 value, const char *str)
{
if (str == NULL)
snprintf(buf, size, "%"PRIu64, value);
else
snprintf(buf, size, "%"PRIu64" (%s)", value, str);
}

> +}
> +
> #define BUF_SIZE 1024
>
> #define p_hex(val) snprintf(buf, BUF_SIZE, "%#"PRIx64, (uint64_t)(val))
> @@ -79,6 +106,7 @@ static void __p_read_format(char *buf, size_t size, u64 value)
> #define p_sample_type(val) __p_sample_type(buf, BUF_SIZE, val)
> #define p_branch_sample_type(val) __p_branch_sample_type(buf, BUF_SIZE, val)
> #define p_read_format(val) __p_read_format(buf, BUF_SIZE, val)
> +#define p_type_id(val) __p_type_id(buf, BUF_SIZE, val)
>
> #define PRINT_ATTRn(_n, _f, _p, _a) \
> do { \
> @@ -96,7 +124,7 @@ int perf_event_attr__fprintf(FILE *fp, struct perf_event_attr *attr,
> char buf[BUF_SIZE];
> int ret = 0;
>
> - PRINT_ATTRf(type, p_unsigned);
> + PRINT_ATTRn("type", type, p_type_id, true);
> PRINT_ATTRf(size, p_unsigned);
> PRINT_ATTRf(config, p_hex);
> PRINT_ATTRn("{ sample_period, sample_freq }", sample_period, p_unsigned, false);