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Message-ID: <ZnLhQLN7jI38qeJE@x1>
Date: Wed, 19 Jun 2024 10:46:40 -0300
From: Arnaldo Carvalho de Melo <acme@...nel.org>
To: Howard Chu <howardchu95@...il.com>
Cc: Jiri Olsa <jolsa@...nel.org>, Namhyung Kim <namhyung@...nel.org>,
Ian Rogers <irogers@...gle.com>,
Adrian Hunter <adrian.hunter@...el.com>,
Kan Liang <kan.liang@...ux.intel.com>, linux-kernel@...r.kernel.org,
linux-perf-users@...r.kernel.org
Subject: Re: [PATCH v2 3/5] perf trace: Augment enum tracepoint arguments
with BTF
On Wed, Jun 19, 2024 at 04:20:40PM +0800, Howard Chu wrote:
> Before:
>
> perf $ ./perf trace -e timer:hrtimer_start --max-events=1
> 0.000 :0/0 timer:hrtimer_start(hrtimer: 0xffff974466c25f18, function: 0xffffffff89da5be0, expires: 377432432256753, softexpires: 377432432256753, mode: 10)
>
> After:
>
> perf $ ./perf trace -e timer:hrtimer_start --max-events=1
> 0.000 :0/0 timer:hrtimer_start(hrtimer: 0xffff974466d25f18, function: 0xffffffff89da5be0, expires: 488283834504945, softexpires: 488283834504945, mode: HRTIMER_MODE_ABS_PINNED_HARD)
>
> HRTIMER_MODE_ABS_PINNED_HARD is:
>
> perf $ pahole hrtimer_mode
> enum hrtimer_mode {
> HRTIMER_MODE_ABS = 0,
> HRTIMER_MODE_REL = 1,
> HRTIMER_MODE_PINNED = 2,
> HRTIMER_MODE_SOFT = 4,
> HRTIMER_MODE_HARD = 8,
> HRTIMER_MODE_ABS_PINNED = 2,
> HRTIMER_MODE_REL_PINNED = 3,
> HRTIMER_MODE_ABS_SOFT = 4,
> HRTIMER_MODE_REL_SOFT = 5,
> HRTIMER_MODE_ABS_PINNED_SOFT = 6,
> HRTIMER_MODE_REL_PINNED_SOFT = 7,
> HRTIMER_MODE_ABS_HARD = 8,
> HRTIMER_MODE_REL_HARD = 9,
> HRTIMER_MODE_ABS_PINNED_HARD = 10,
> HRTIMER_MODE_REL_PINNED_HARD = 11,
> };
>
> Can also be tested by
>
> ./perf trace -e pagemap:mm_lru_insertion,timer:hrtimer_start,timer:hrtimer_init,skb:kfree_skb --max-events=10
>
> (Chose these 4 events because they happen quite frequently.)
>
> However some enum arguments may not be contained in vmlinux BTF. To see
> what enum arguments are supported, use:
>
> vmlinux_dir $ bpftool btf dump file /sys/kernel/btf/vmlinux > vmlinux
>
> vmlinux_dir $ while read l; do grep "ENUM '$l'" vmlinux; done < <(grep field:enum /sys/kernel/tracing/events/*/*/format | awk '{print $3}' | sort | uniq) | awk '{print $3}' | sed "s/'\(.*\)'/\1/g"
> dev_pm_qos_req_type
> error_detector
> hrtimer_mode
> i2c_slave_event
> ieee80211_bss_type
> lru_list
> migrate_mode
> nl80211_auth_type
> nl80211_band
> nl80211_iftype
> numa_vmaskip_reason
> pm_qos_req_action
> pwm_polarity
> skb_drop_reason
> thermal_trip_type
> xen_lazy_mode
> xen_mc_extend_args
> xen_mc_flush_reason
> zone_type
>
> And what tracepoints have these enum types as their arguments:
>
> vmlinux_dir $ while read l; do grep "ENUM '$l'" vmlinux; done < <(grep field:enum /sys/kernel/tracing/events/*/*/format | awk '{print $3}' | sort | uniq) | awk '{print $3}' | sed "s/'\(.*\)'/\1/g" > good_enums
>
> vmlinux_dir $ cat good_enums
> dev_pm_qos_req_type
> error_detector
> hrtimer_mode
> i2c_slave_event
> ieee80211_bss_type
> lru_list
> migrate_mode
> nl80211_auth_type
> nl80211_band
> nl80211_iftype
> numa_vmaskip_reason
> pm_qos_req_action
> pwm_polarity
> skb_drop_reason
> thermal_trip_type
> xen_lazy_mode
> xen_mc_extend_args
> xen_mc_flush_reason
> zone_type
>
> vmlinux_dir $ grep -f good_enums -l /sys/kernel/tracing/events/*/*/format
> /sys/kernel/tracing/events/cfg80211/cfg80211_chandef_dfs_required/format
> /sys/kernel/tracing/events/cfg80211/cfg80211_ch_switch_notify/format
> /sys/kernel/tracing/events/cfg80211/cfg80211_ch_switch_started_notify/format
> /sys/kernel/tracing/events/cfg80211/cfg80211_get_bss/format
> /sys/kernel/tracing/events/cfg80211/cfg80211_ibss_joined/format
> /sys/kernel/tracing/events/cfg80211/cfg80211_inform_bss_frame/format
> /sys/kernel/tracing/events/cfg80211/cfg80211_radar_event/format
> /sys/kernel/tracing/events/cfg80211/cfg80211_ready_on_channel_expired/format
> /sys/kernel/tracing/events/cfg80211/cfg80211_ready_on_channel/format
> /sys/kernel/tracing/events/cfg80211/cfg80211_reg_can_beacon/format
> /sys/kernel/tracing/events/cfg80211/cfg80211_return_bss/format
> /sys/kernel/tracing/events/cfg80211/cfg80211_tx_mgmt_expired/format
> /sys/kernel/tracing/events/cfg80211/rdev_add_virtual_intf/format
> /sys/kernel/tracing/events/cfg80211/rdev_auth/format
> /sys/kernel/tracing/events/cfg80211/rdev_change_virtual_intf/format
> /sys/kernel/tracing/events/cfg80211/rdev_channel_switch/format
> /sys/kernel/tracing/events/cfg80211/rdev_connect/format
> /sys/kernel/tracing/events/cfg80211/rdev_inform_bss/format
> /sys/kernel/tracing/events/cfg80211/rdev_libertas_set_mesh_channel/format
> /sys/kernel/tracing/events/cfg80211/rdev_mgmt_tx/format
> /sys/kernel/tracing/events/cfg80211/rdev_remain_on_channel/format
> /sys/kernel/tracing/events/cfg80211/rdev_return_chandef/format
> /sys/kernel/tracing/events/cfg80211/rdev_return_int_survey_info/format
> /sys/kernel/tracing/events/cfg80211/rdev_set_ap_chanwidth/format
> /sys/kernel/tracing/events/cfg80211/rdev_set_monitor_channel/format
> /sys/kernel/tracing/events/cfg80211/rdev_set_radar_background/format
> /sys/kernel/tracing/events/cfg80211/rdev_start_ap/format
> /sys/kernel/tracing/events/cfg80211/rdev_start_radar_detection/format
> /sys/kernel/tracing/events/cfg80211/rdev_tdls_channel_switch/format
> /sys/kernel/tracing/events/compaction/mm_compaction_defer_compaction/format
> /sys/kernel/tracing/events/compaction/mm_compaction_deferred/format
> /sys/kernel/tracing/events/compaction/mm_compaction_defer_reset/format
> /sys/kernel/tracing/events/compaction/mm_compaction_finished/format
> /sys/kernel/tracing/events/compaction/mm_compaction_kcompactd_wake/format
> /sys/kernel/tracing/events/compaction/mm_compaction_suitable/format
> /sys/kernel/tracing/events/compaction/mm_compaction_wakeup_kcompactd/format
> /sys/kernel/tracing/events/error_report/error_report_end/format
> /sys/kernel/tracing/events/i2c_slave/i2c_slave/format
> /sys/kernel/tracing/events/migrate/mm_migrate_pages/format
> /sys/kernel/tracing/events/migrate/mm_migrate_pages_start/format
> /sys/kernel/tracing/events/pagemap/mm_lru_insertion/format
> /sys/kernel/tracing/events/power/dev_pm_qos_add_request/format
> /sys/kernel/tracing/events/power/dev_pm_qos_remove_request/format
> /sys/kernel/tracing/events/power/dev_pm_qos_update_request/format
> /sys/kernel/tracing/events/power/pm_qos_update_flags/format
> /sys/kernel/tracing/events/power/pm_qos_update_target/format
> /sys/kernel/tracing/events/pwm/pwm_apply/format
> /sys/kernel/tracing/events/pwm/pwm_get/format
> /sys/kernel/tracing/events/sched/sched_skip_vma_numa/format
> /sys/kernel/tracing/events/skb/kfree_skb/format
> /sys/kernel/tracing/events/thermal/thermal_zone_trip/format
> /sys/kernel/tracing/events/timer/hrtimer_init/format
> /sys/kernel/tracing/events/timer/hrtimer_start/format
> /sys/kernel/tracing/events/xen/xen_mc_batch/format
> /sys/kernel/tracing/events/xen/xen_mc_extend_args/format
> /sys/kernel/tracing/events/xen/xen_mc_flush_reason/format
> /sys/kernel/tracing/events/xen/xen_mc_issue/format
>
> Tested-by: Arnaldo Carvalho de Melo <acme@...nel.org>
> Suggested-by: Arnaldo Carvalho de Melo <acme@...nel.org>
> Reviewed-by: Arnaldo Carvalho de Melo <acme@...nel.org>
> Signed-off-by: Howard Chu <howardchu95@...il.com>
> ---
> tools/perf/builtin-trace.c | 29 ++++++++++++++++++++++-------
> 1 file changed, 22 insertions(+), 7 deletions(-)
>
> diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
> index d93f34e9af74..bd16679fb4c0 100644
> --- a/tools/perf/builtin-trace.c
> +++ b/tools/perf/builtin-trace.c
> @@ -1962,12 +1962,12 @@ static int trace__read_syscall_info(struct trace *trace, int id)
> return err;
> }
>
> -static int evsel__init_tp_arg_scnprintf(struct evsel *evsel)
> +static int evsel__init_tp_arg_scnprintf(struct evsel *evsel, bool *use_btf)
> {
> struct syscall_arg_fmt *fmt = evsel__syscall_arg_fmt(evsel);
>
> if (fmt != NULL) {
> - syscall_arg_fmt__init_array(fmt, evsel->tp_format->format.fields, NULL);
> + syscall_arg_fmt__init_array(fmt, evsel->tp_format->format.fields, use_btf);
> return 0;
> }
>
> @@ -2171,7 +2171,8 @@ static size_t syscall__scnprintf_args(struct syscall *sc, char *bf, size_t size,
> * property isn't set.
> */
> if (val == 0 && !trace->show_zeros &&
> - !(sc->arg_fmt && sc->arg_fmt[arg.idx].show_zero))
> + !(sc->arg_fmt && sc->arg_fmt[arg.idx].show_zero) &&
> + !(sc->arg_fmt && sc->arg_fmt[arg.idx].is_enum))
> continue;
>
> printed += scnprintf(bf + printed, size - printed, "%s", printed ? ", " : "");
> @@ -2877,7 +2878,7 @@ static size_t trace__fprintf_tp_fields(struct trace *trace, struct evsel *evsel,
> val = syscall_arg_fmt__mask_val(arg, &syscall_arg, val);
>
> /* Suppress this argument if its value is zero and show_zero property isn't set. */
> - if (val == 0 && !trace->show_zeros && !arg->show_zero)
> + if (val == 0 && !trace->show_zeros && !arg->show_zero && !arg->is_enum)
> continue;
>
> printed += scnprintf(bf + printed, size - printed, "%s", printed ? ", " : "");
> @@ -2885,6 +2886,15 @@ static size_t trace__fprintf_tp_fields(struct trace *trace, struct evsel *evsel,
> if (trace->show_arg_names)
> printed += scnprintf(bf + printed, size - printed, "%s: ", field->name);
>
> + if (arg->is_enum && trace->btf) {
> + size_t p = btf_enum_scnprintf(bf + printed, size - printed, val, trace->btf,
> + field->type, arg);
> + if (p) {
> + printed += p;
> + continue;
> + }
> + }
> +
> printed += syscall_arg_fmt__scnprintf_val(arg, bf + printed, size - printed, &syscall_arg, val);
> }
>
> @@ -4537,7 +4547,7 @@ static void evsel__set_syscall_arg_fmt(struct evsel *evsel, const char *name)
> }
> }
>
> -static int evlist__set_syscall_tp_fields(struct evlist *evlist)
> +static int evlist__set_syscall_tp_fields(struct evlist *evlist, bool *use_btf)
> {
> struct evsel *evsel;
>
> @@ -4546,7 +4556,7 @@ static int evlist__set_syscall_tp_fields(struct evlist *evlist)
> continue;
>
> if (strcmp(evsel->tp_format->system, "syscalls")) {
> - evsel__init_tp_arg_scnprintf(evsel);
> + evsel__init_tp_arg_scnprintf(evsel, use_btf);
> continue;
> }
>
> @@ -5024,11 +5034,16 @@ int cmd_trace(int argc, const char **argv)
> }
>
> if (trace.evlist->core.nr_entries > 0) {
> + bool use_btf = false;
> +
> evlist__set_default_evsel_handler(trace.evlist, trace__event_handler);
> - if (evlist__set_syscall_tp_fields(trace.evlist)) {
> + if (evlist__set_syscall_tp_fields(trace.evlist, &use_btf)) {
> perror("failed to set syscalls:* tracepoint fields");
> goto out;
> }
> +
> + if (use_btf && trace.btf == NULL)
> + trace__load_vmlinux_btf(&trace);
Can we defer loading btf to when one of those tracepoints is hit?
> }
>
> if (trace.sort_events) {
> --
> 2.45.2
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