| From: Tom Zanussi <tom.zanussi@linux.intel.com> |
| Date: Tue, 5 Sep 2017 16:57:44 -0500 |
| Subject: [PATCH 32/40] tracing: Add cpu field for hist triggers |
| |
| A common key to use in a histogram is the cpuid - add a new cpu |
| 'synthetic' field for that purpose. This field is named cpu rather |
| than $cpu or $common_cpu because 'cpu' already exists as a special |
| filter field and it makes more sense to match that rather than add |
| another name for the same thing. |
| |
| Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com> |
| Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> |
| --- |
| Documentation/trace/events.txt | 18 ++++++++++++++++++ |
| kernel/trace/trace_events_hist.c | 30 +++++++++++++++++++++++++++--- |
| 2 files changed, 45 insertions(+), 3 deletions(-) |
| |
| --- a/Documentation/trace/events.txt |
| +++ b/Documentation/trace/events.txt |
| @@ -668,6 +668,24 @@ triggers (you have to use '!' for each o |
| The examples below provide a more concrete illustration of the |
| concepts and typical usage patterns discussed above. |
| |
| + 'synthetic' event fields |
| + ------------------------ |
| + |
| + There are a number of 'synthetic fields' available for use as keys |
| + or values in a hist trigger. These look like and behave as if they |
| + were event fields, but aren't actually part of the event's field |
| + definition or format file. They are however available for any |
| + event, and can be used anywhere an actual event field could be. |
| + 'Synthetic' field names are always prefixed with a '$' character to |
| + indicate that they're not normal fields (with the exception of |
| + 'cpu', for compatibility with existing filter usage): |
| + |
| + $common_timestamp u64 - timestamp (from ring buffer) associated |
| + with the event, in nanoseconds. May be |
| + modified by .usecs to have timestamps |
| + interpreted as microseconds. |
| + cpu int - the cpu on which the event occurred. |
| + |
| |
| 6.2 'hist' trigger examples |
| --------------------------- |
| --- a/kernel/trace/trace_events_hist.c |
| +++ b/kernel/trace/trace_events_hist.c |
| @@ -226,6 +226,7 @@ enum hist_field_flags { |
| HIST_FIELD_FL_VAR_ONLY = 8192, |
| HIST_FIELD_FL_EXPR = 16384, |
| HIST_FIELD_FL_VAR_REF = 32768, |
| + HIST_FIELD_FL_CPU = 65536, |
| }; |
| |
| struct var_defs { |
| @@ -1170,6 +1171,16 @@ static u64 hist_field_timestamp(struct h |
| return ts; |
| } |
| |
| +static u64 hist_field_cpu(struct hist_field *hist_field, |
| + struct tracing_map_elt *elt, |
| + struct ring_buffer_event *rbe, |
| + void *event) |
| +{ |
| + int cpu = raw_smp_processor_id(); |
| + |
| + return cpu; |
| +} |
| + |
| static struct hist_field *check_var_ref(struct hist_field *hist_field, |
| struct hist_trigger_data *var_data, |
| unsigned int var_idx) |
| @@ -1518,6 +1529,8 @@ static const char *hist_field_name(struc |
| field_name = hist_field_name(field->operands[0], ++level); |
| else if (field->flags & HIST_FIELD_FL_TIMESTAMP) |
| field_name = "$common_timestamp"; |
| + else if (field->flags & HIST_FIELD_FL_CPU) |
| + field_name = "cpu"; |
| else if (field->flags & HIST_FIELD_FL_EXPR || |
| field->flags & HIST_FIELD_FL_VAR_REF) |
| field_name = field->name; |
| @@ -1990,6 +2003,15 @@ static struct hist_field *create_hist_fi |
| goto out; |
| } |
| |
| + if (flags & HIST_FIELD_FL_CPU) { |
| + hist_field->fn = hist_field_cpu; |
| + hist_field->size = sizeof(int); |
| + hist_field->type = kstrdup("int", GFP_KERNEL); |
| + if (!hist_field->type) |
| + goto free; |
| + goto out; |
| + } |
| + |
| if (WARN_ON_ONCE(!field)) |
| goto out; |
| |
| @@ -2182,7 +2204,9 @@ parse_field(struct hist_trigger_data *hi |
| hist_data->enable_timestamps = true; |
| if (*flags & HIST_FIELD_FL_TIMESTAMP_USECS) |
| hist_data->attrs->ts_in_usecs = true; |
| - } else { |
| + } else if (strcmp(field_name, "cpu") == 0) |
| + *flags |= HIST_FIELD_FL_CPU; |
| + else { |
| field = trace_find_event_field(file->event_call, field_name); |
| if (!field || !field->size) { |
| field = ERR_PTR(-EINVAL); |
| @@ -3185,7 +3209,6 @@ static int onmatch_create(struct hist_tr |
| goto out; |
| } |
| } |
| - |
| if (param[0] == '$') |
| hist_field = onmatch_find_var(hist_data, data, system, |
| event_name, param); |
| @@ -3200,7 +3223,6 @@ static int onmatch_create(struct hist_tr |
| ret = -EINVAL; |
| goto out; |
| } |
| - |
| if (check_synth_field(event, hist_field, field_pos) == 0) { |
| var_ref = create_var_ref(hist_field); |
| if (!var_ref) { |
| @@ -4315,6 +4337,8 @@ static void hist_field_print(struct seq_ |
| |
| if (hist_field->flags & HIST_FIELD_FL_TIMESTAMP) |
| seq_puts(m, "$common_timestamp"); |
| + else if (hist_field->flags & HIST_FIELD_FL_CPU) |
| + seq_puts(m, "cpu"); |
| else if (field_name) |
| seq_printf(m, "%s", field_name); |
| |