Hi Tom,
On Wed, Dec 06, 2017 at 04:37:56PM -0600, Tom Zanussi wrote:
> Add support for saving the value of a current event's event field by
> assigning it to a variable that can be read by a subsequent event.
>
> The basic syntax for saving a variable is to simply prefix a unique
> variable name not corresponding to any keyword along with an '=' sign
> to any event field.
>
> Both keys and values can be saved and retrieved in this way:
>
> # echo 'hist:keys=next_pid:vals=$ts0:ts0=common_timestamp ...
> # echo 'hist:timer_pid=common_pid:key=$timer_pid ...'
>
> If a variable isn't a key variable or prefixed with 'vals=', the
> associated event field will be saved in a variable but won't be summed
> as a value:
>
> # echo 'hist:keys=next_pid:ts1=common_timestamp:...
>
> Multiple variables can be assigned at the same time:
>
> # echo 'hist:keys=pid:vals=$ts0,$b,field2:ts0=common_timestamp,b=field1 ...
>
> Multiple (or single) variables can also be assigned at the same time
> using separate assignments:
>
> # echo 'hist:keys=pid:vals=$ts0:ts0=common_timestamp:b=field1:c=field2 ...
>
> Variables set as above can be used by being referenced from another
> event, as described in a subsequent patch.
>
> Signed-off-by: Tom Zanussi <tom.zanussi@xxxxxxxxxxxxxxx>
> Signed-off-by: Baohong Liu <baohong.liu@xxxxxxxxx>
> ---
[SNIP]
> @@ -962,14 +1201,28 @@ static void hist_trigger_elt_update(struct hist_trigger_data *hist_data,
> struct ring_buffer_event *rbe)
> {
> struct hist_field *hist_field;
> - unsigned int i;
> + unsigned int i, var_idx;
> u64 hist_val;
>
> for_each_hist_val_field(i, hist_data) {
> hist_field = hist_data->fields[i];
> - hist_val = hist_field->fn(hist_field, rec, rbe);
> + hist_val = hist_field->fn(hist_field, rbe, rec);
Why is this changed?
> + if (hist_field->flags & HIST_FIELD_FL_VAR) {
> + var_idx = hist_field->var.idx;
> + tracing_map_set_var(elt, var_idx, hist_val);
> + continue;
> + }
> tracing_map_update_sum(elt, i, hist_val);
> }
> +
> + for_each_hist_key_field(i, hist_data) {
> + hist_field = hist_data->fields[i];
> + if (hist_field->flags & HIST_FIELD_FL_VAR) {
> + hist_val = hist_field->fn(hist_field, rbe, rec);
Also it seems to have a wrong argument order.
Thanks,
Namhyung
> + var_idx = hist_field->var.idx;
> + tracing_map_set_var(elt, var_idx, hist_val);
> + }
> + }
> }
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