On 2015/07/17 2:22, Tom Zanussi wrote:
> Allow users to append 'clear' to an existing trigger in order to have
> the hash table cleared.
>
> This expands the hist trigger syntax from this:
> # echo hist:keys=xxx:vals=yyy:sort=zzz.descending:pause/cont \
> [ if filter] > event/trigger
>
> to this:
>
> # echo hist:keys=xxx:vals=yyy:sort=zzz.descending:pause/cont/clear \
> [ if filter] > event/trigger
By the way, since pause/cont/clear is not the trigger but the commands
(which executed immediately), I think it should be a write fops of
"hist" special file.
e.g. to clear the histogram, write 0 to hist
# echo 0 > event/hist
And pause/cont will be 1 and 2.
# echo 1 > event/hist <- pause
and
# echo 2 > event/hist <- continue
What would you think ?
Thanks,
>
> Signed-off-by: Tom Zanussi <tom.zanu...@linux.intel.com>
> ---
> kernel/trace/trace.c | 4 +++-
> kernel/trace/trace_events_hist.c | 25 ++++++++++++++++++++++++-
> 2 files changed, 27 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> index 547bbc8..27daa28 100644
> --- a/kernel/trace/trace.c
> +++ b/kernel/trace/trace.c
> @@ -3791,7 +3791,7 @@ static const char readme_msg[] =
> "\t [:values=<field1[,field2,...]]\n"
> "\t [:sort=field1,field2,...]\n"
> "\t [:size=#entries]\n"
> - "\t [:pause][:continue]\n"
> + "\t [:pause][:continue][:clear]\n"
> "\t [if <filter>]\n\n"
> "\t When a matching event is hit, an entry is added to a hash\n"
> "\t table using the key(s) and value(s) named. Keys and values\n"
> @@ -3826,6 +3826,8 @@ static const char readme_msg[] =
> "\t trigger or to start a hist trigger but not log any events\n"
> "\t until told to do so. 'continue' can be used to start or\n"
> "\t restart a paused hist trigger.\n\n"
> + "\t The 'clear' param will clear the contents of a running hist\n"
> + "\t trigger and leave its current paused/active state.\n\n"
> #endif
> ;
>
> diff --git a/kernel/trace/trace_events_hist.c
> b/kernel/trace/trace_events_hist.c
> index 3ae58e7..d8259fe 100644
> --- a/kernel/trace/trace_events_hist.c
> +++ b/kernel/trace/trace_events_hist.c
> @@ -80,6 +80,7 @@ struct hist_trigger_attrs {
> char *sort_key_str;
> bool pause;
> bool cont;
> + bool clear;
> unsigned int map_bits;
> };
>
> @@ -188,6 +189,8 @@ static struct hist_trigger_attrs
> *parse_hist_trigger_attrs(char *trigger_str)
> attrs->sort_key_str = kstrdup(str, GFP_KERNEL);
> else if (!strncmp(str, "pause", strlen("pause")))
> attrs->pause = true;
> + else if (!strncmp(str, "clear", strlen("clear")))
> + attrs->clear = true;
> else if (!strncmp(str, "continue", strlen("continue")) ||
> !strncmp(str, "cont", strlen("cont")))
> attrs->cont = true;
> @@ -888,6 +891,24 @@ static struct event_trigger_ops
> *event_hist_get_trigger_ops(char *cmd,
> return &event_hist_trigger_ops;
> }
>
> +static void hist_clear(struct event_trigger_data *data)
> +{
> + struct hist_trigger_data *hist_data = data->private_data;
> + bool paused;
> +
> + paused = data->paused;
> + data->paused = true;
> +
> + synchronize_sched();
> +
> + tracing_map_clear(hist_data->map);
> +
> + atomic64_set(&hist_data->total_hits, 0);
> + atomic64_set(&hist_data->drops, 0);
> +
> + data->paused = paused;
> +}
> +
> static int hist_register_trigger(char *glob, struct event_trigger_ops *ops,
> struct event_trigger_data *data,
> struct trace_event_file *file)
> @@ -902,6 +923,8 @@ static int hist_register_trigger(char *glob, struct
> event_trigger_ops *ops,
> test->paused = true;
> else if (hist_data->attrs->cont)
> test->paused = false;
> + else if (hist_data->attrs->clear)
> + hist_clear(test);
> else
> ret = -EEXIST;
> goto out;
> @@ -1003,7 +1026,7 @@ static int event_hist_trigger_func(struct event_command
> *cmd_ops,
> * triggers registered a failure too.
> */
> if (!ret) {
> - if (!(attrs->pause || attrs->cont))
> + if (!(attrs->pause || attrs->cont || attrs->clear))
> ret = -ENOENT;
> goto out_free;
> } else if (ret < 0)
>
--
Masami HIRAMATSU
Linux Technology Research Center, System Productivity Research Dept.
Center for Technology Innovation - Systems Engineering
Hitachi, Ltd., Research & Development Group
E-mail: masami.hiramatsu...@hitachi.com
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