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SubjectRe: [PATCH v9 14/22] tracing: Add hist trigger 'hex' modifier for displaying numeric fields
Hi Tom,

On Thu, Jul 16, 2015 at 12:22:47PM -0500, Tom Zanussi wrote:
> Allow users to have numeric fields displayed as hex values in the
> output by appending '.hex' to field names:
>
> # echo hist:keys=aaa,bbb.hex:vals=ccc.hex ... \
> [ if filter] > event/trigger
>
> Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
> ---
> kernel/trace/trace.c | 5 +++-
> kernel/trace/trace_events_hist.c | 49 +++++++++++++++++++++++++++++++++++++---
> 2 files changed, 50 insertions(+), 4 deletions(-)
>
> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> index 27daa28..14f9472 100644
> --- a/kernel/trace/trace.c
> +++ b/kernel/trace/trace.c
> @@ -3810,7 +3810,10 @@ static const char readme_msg[] =
> "\t entry is a simple list of the keys and values comprising the\n"
> "\t entry; keys are printed first and are delineated by curly\n"
> "\t braces, and are followed by the set of value fields for the\n"
> - "\t entry. Numeric fields are displayed as base-10 integers.\n"
> + "\t entry. By default, numeric fields are displayed as base-10\n"
> + "\t integers. This can be modified by appending any of the\n"
> + "\t following modifiers to the field name:\n\n"
> + "\t .hex display a number as a hex value\n\n"
> "\t By default, the size of the hash table is 2048 entries. The\n"
> "\t 'size' param can be used to specify more or fewer than that.\n"
> "\t The units are in terms of hashtable entries - if a run uses\n"
> diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
> index d8259fe..9cc38ee 100644
> --- a/kernel/trace/trace_events_hist.c
> +++ b/kernel/trace/trace_events_hist.c
> @@ -72,6 +72,7 @@ enum hist_field_flags {
> HIST_FIELD_HITCOUNT = 1,
> HIST_FIELD_KEY = 2,
> HIST_FIELD_STRING = 4,
> + HIST_FIELD_HEX = 8,
> };
>
> struct hist_trigger_attrs {
> @@ -284,9 +285,20 @@ static int create_val_field(struct hist_trigger_data *hist_data,
> {
> struct ftrace_event_field *field = NULL;
> unsigned long flags = 0;
> + char *field_name;
> int ret = 0;
>
> - field = trace_find_event_field(file->event_call, field_str);
> + field_name = strsep(&field_str, ".");
> + if (field_str) {
> + if (!strcmp(field_str, "hex"))
> + flags |= HIST_FIELD_HEX;
> + else {
> + ret = -EINVAL;
> + goto out;
> + }
> + }
> +
> + field = trace_find_event_field(file->event_call, field_name);
> if (!field) {
> ret = -EINVAL;
> goto out;
> @@ -349,11 +361,22 @@ static int create_key_field(struct hist_trigger_data *hist_data,
> struct ftrace_event_field *field = NULL;
> unsigned long flags = 0;
> unsigned int key_size;
> + char *field_name;
> int ret = 0;
>
> flags |= HIST_FIELD_KEY;
>
> - field = trace_find_event_field(file->event_call, field_str);
> + field_name = strsep(&field_str, ".");
> + if (field_str) {
> + if (!strcmp(field_str, "hex"))
> + flags |= HIST_FIELD_HEX;
> + else {
> + ret = -EINVAL;
> + goto out;
> + }
> + }
> +
> + field = trace_find_event_field(file->event_call, field_name);
> if (!field) {
> ret = -EINVAL;
> goto out;
> @@ -688,7 +711,11 @@ hist_trigger_entry_print(struct seq_file *m,
> if (i > hist_data->n_vals)
> seq_puts(m, ", ");
>
> - if (key_field->flags & HIST_FIELD_STRING) {
> + if (key_field->flags & HIST_FIELD_HEX) {
> + uval = *(u64 *)(key + key_field->offset);
> + seq_printf(m, "%s: %llx",
> + key_field->field->name, uval);
> + } else if (key_field->flags & HIST_FIELD_STRING) {
> seq_printf(m, "%s: %-35s", key_field->field->name,
> (char *)(key + key_field->offset));
> } else {

It seems the '.hex' modifier only affects key fields' output..

Thanks,
Namhyung


> @@ -791,9 +818,25 @@ const struct file_operations event_hist_fops = {
> .release = single_release,
> };
>
> +static const char *get_hist_field_flags(struct hist_field *hist_field)
> +{
> + const char *flags_str = NULL;
> +
> + if (hist_field->flags & HIST_FIELD_HEX)
> + flags_str = "hex";
> +
> + return flags_str;
> +}
> +
> static void hist_field_print(struct seq_file *m, struct hist_field *hist_field)
> {
> seq_printf(m, "%s", hist_field->field->name);
> + if (hist_field->flags) {
> + const char *flags_str = get_hist_field_flags(hist_field);
> +
> + if (flags_str)
> + seq_printf(m, ".%s", flags_str);
> + }
> }
>
> static int event_hist_trigger_print(struct seq_file *m,
> --
> 1.9.3
>


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