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Date: Tue, 21 Jul 2015 11:10:35 -0500
From: Tom Zanussi <tom.zanussi@...ux.intel.com>
To: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
Cc: rostedt@...dmis.org, daniel.wagner@...-carit.de,
namhyung@...nel.org, josh@...htriplett.org, andi@...stfloor.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v9 21/22] tracing: Add enable_hist/disable_hist triggers
Hi Masami,
On Mon, 2015-07-20 at 23:57 +0900, Masami Hiramatsu wrote:
> On 2015/07/17 2:22, Tom Zanussi wrote:
> > Similar to enable_event/disable_event triggers, these triggers enable
> > and disable the aggregation of events into maps rather than enabling
> > and disabling their writing into the trace buffer.
> >
> > They can be used to automatically start and stop hist triggers based
> > on a matching filter condition.
> >
> > If there's a paused hist trigger on system:event, the following would
> > start it when the filter condition was hit:
> >
> > # echo enable_hist:system:event [ if filter] > event/trigger
> >
> > And the following would disable a running system:event hist trigger:
> >
> > # echo disable_hist:system:event [ if filter] > event/trigger
> >
> > See Documentation/trace/events.txt for real examples.
>
> Hmm, do we really need this? Since we've already had multiple instances,
> if someone wants to make histogram separated from event logger, he/she can
> make another instance for that, and disable/enable event itself.
>
> I'm considering if we accept this methods, we'll need to accept another
> enable/disable triggers for each action too in the future.
>
OK, I haven't implemented multiple instances yet, but if I understand
you correctly, what you're suggesting is that we can accomplish the same
thing, by setting up a disabled histogram on system:event and then
simply using the existing enable_event:system:event trigger to turn it
on. Likewise the opposite to disable it.
I guess we need to add the histogram instance name to the syntax of
enable_event:system:event to be able to make the distinction between a
histogram and the current behavior of enabling logging.
So here's what we currently have. This sets up a histogram and starts
it running, and the user cats event/hist to get the results:
# echo hist:keys=xxx > event1/trigger
# cat event1/hist
And separately the existing enable_event trigger, which enables event1
(starts it logging to the event logger, and has nothing to do with
histograms) when event2 is hit:
# echo enable_event:system:event1 > event2/trigger
So to extend enable_event to support histograms, we need to be able to
do this, first set up a paused histogram:
# echo hist:keys=xxx:pause > event1/trigger
# cat event1/hist
Which would be enabled via enable_event like this:
# echo enable_event:system:event1:hist > event2/trigger
Of course 'hist' refers to the initial single-instance histogram - if we
had multiple instances, 'hist' would be replaced by the instance name
e.g. to set up two different histograms, each with a different filter:
# echo hist:keys=xxx:pause if filter1 > event1/trigger
# cat event1/hist
# echo hist:keys=xxx:pause if filter2 > event1/trigger
# cat event1/hist2
To enable the first histogram when event2 is hit:
# echo enable_event:system:event1:hist > event2/trigger
And to enable the second histogram when event2 is hit:
# echo enable_event:system:event1:hist2 > event2/trigger
Does that align with what you were thinking regarding both instances and
the enable/disable_event triggers? If not, some more explanation and
examples would help ;-)
Thanks,
Tom
> Thank you,
>
> >
> > Signed-off-by: Tom Zanussi <tom.zanussi@...ux.intel.com>
> > ---
> > include/linux/trace_events.h | 1 +
> > kernel/trace/trace.c | 11 ++++
> > kernel/trace/trace.h | 32 ++++++++++
> > kernel/trace/trace_events_hist.c | 115 ++++++++++++++++++++++++++++++++++++
> > kernel/trace/trace_events_trigger.c | 71 ++++++++++++----------
> > 5 files changed, 199 insertions(+), 31 deletions(-)
> >
> > diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h
> > index 0faf48b..0f3ffdd 100644
> > --- a/include/linux/trace_events.h
> > +++ b/include/linux/trace_events.h
> > @@ -411,6 +411,7 @@ enum event_trigger_type {
> > ETT_STACKTRACE = (1 << 2),
> > ETT_EVENT_ENABLE = (1 << 3),
> > ETT_EVENT_HIST = (1 << 4),
> > + ETT_HIST_ENABLE = (1 << 5),
> > };
> >
> > extern int filter_match_preds(struct event_filter *filter, void *rec);
> > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> > index 16c64a2..c581750 100644
> > --- a/kernel/trace/trace.c
> > +++ b/kernel/trace/trace.c
> > @@ -3761,6 +3761,10 @@ static const char readme_msg[] =
> > "\t trigger: traceon, traceoff\n"
> > "\t enable_event:<system>:<event>\n"
> > "\t disable_event:<system>:<event>\n"
> > +#ifdef CONFIG_HIST_TRIGGERS
> > + "\t enable_hist:<system>:<event>\n"
> > + "\t disable_hist:<system>:<event>\n"
> > +#endif
> > #ifdef CONFIG_STACKTRACE
> > "\t\t stacktrace\n"
> > #endif
> > @@ -3836,6 +3840,13 @@ static const char readme_msg[] =
> > "\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"
> > + "\t The enable_hist and disable_hist triggers can be used to\n"
> > + "\t have one event conditionally start and stop another event's\n"
> > + "\t already-attached hist trigger. Any number of enable_hist\n"
> > + "\t and disable_hist triggers can be attached to a given event,\n"
> > + "\t allowing that event to kick off and stop aggregations on\n"
> > + "\t a host of other events. See Documentation/trace/events.txt\n"
> > + "\t for examples.\n"
> > #endif
> > ;
> >
> > diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
> > index e6cb781..5e2e3b0 100644
> > --- a/kernel/trace/trace.h
> > +++ b/kernel/trace/trace.h
> > @@ -1102,8 +1102,10 @@ extern const struct file_operations event_hist_fops;
> >
> > #ifdef CONFIG_HIST_TRIGGERS
> > extern int register_trigger_hist_cmd(void);
> > +extern int register_trigger_hist_enable_disable_cmds(void);
> > #else
> > static inline int register_trigger_hist_cmd(void) { return 0; }
> > +static inline int register_trigger_hist_enable_disable_cmds(void) { return 0; }
> > #endif
> >
> > extern int register_trigger_cmds(void);
> > @@ -1121,6 +1123,34 @@ struct event_trigger_data {
> > struct list_head list;
> > };
> >
> > +/* Avoid typos */
> > +#define ENABLE_EVENT_STR "enable_event"
> > +#define DISABLE_EVENT_STR "disable_event"
> > +#define ENABLE_HIST_STR "enable_hist"
> > +#define DISABLE_HIST_STR "disable_hist"
> > +
> > +struct enable_trigger_data {
> > + struct trace_event_file *file;
> > + bool enable;
> > + bool hist;
> > +};
> > +
> > +extern int event_enable_trigger_print(struct seq_file *m,
> > + struct event_trigger_ops *ops,
> > + struct event_trigger_data *data);
> > +extern void event_enable_trigger_free(struct event_trigger_ops *ops,
> > + struct event_trigger_data *data);
> > +extern int event_enable_trigger_func(struct event_command *cmd_ops,
> > + struct trace_event_file *file,
> > + char *glob, char *cmd, char *param);
> > +extern int event_enable_register_trigger(char *glob,
> > + struct event_trigger_ops *ops,
> > + struct event_trigger_data *data,
> > + struct trace_event_file *file);
> > +extern void event_enable_unregister_trigger(char *glob,
> > + struct event_trigger_ops *ops,
> > + struct event_trigger_data *test,
> > + struct trace_event_file *file);
> > extern void trigger_data_free(struct event_trigger_data *data);
> > extern int event_trigger_init(struct event_trigger_ops *ops,
> > struct event_trigger_data *data);
> > @@ -1134,6 +1164,8 @@ extern int set_trigger_filter(char *filter_str,
> > struct event_trigger_data *trigger_data,
> > struct trace_event_file *file);
> > extern int register_event_command(struct event_command *cmd);
> > +extern int unregister_event_command(struct event_command *cmd);
> > +extern int register_trigger_hist_enable_disable_cmds(void);
> >
> > /**
> > * struct event_trigger_ops - callbacks for trace event triggers
> > diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
> > index 4ba7645..6a43611 100644
> > --- a/kernel/trace/trace_events_hist.c
> > +++ b/kernel/trace/trace_events_hist.c
> > @@ -1345,3 +1345,118 @@ __init int register_trigger_hist_cmd(void)
> >
> > return ret;
> > }
> > +
> > +static void
> > +hist_enable_trigger(struct event_trigger_data *data, void *rec)
> > +{
> > + struct enable_trigger_data *enable_data = data->private_data;
> > + struct event_trigger_data *test;
> > +
> > + list_for_each_entry_rcu(test, &enable_data->file->triggers, list) {
> > + if (test->cmd_ops->trigger_type == ETT_EVENT_HIST) {
> > + if (enable_data->enable)
> > + test->paused = false;
> > + else
> > + test->paused = true;
> > + break;
> > + }
> > + }
> > +}
> > +
> > +static void
> > +hist_enable_count_trigger(struct event_trigger_data *data, void *rec)
> > +{
> > + if (!data->count)
> > + return;
> > +
> > + if (data->count != -1)
> > + (data->count)--;
> > +
> > + hist_enable_trigger(data, rec);
> > +}
> > +
> > +static struct event_trigger_ops hist_enable_trigger_ops = {
> > + .func = hist_enable_trigger,
> > + .print = event_enable_trigger_print,
> > + .init = event_trigger_init,
> > + .free = event_enable_trigger_free,
> > +};
> > +
> > +static struct event_trigger_ops hist_enable_count_trigger_ops = {
> > + .func = hist_enable_count_trigger,
> > + .print = event_enable_trigger_print,
> > + .init = event_trigger_init,
> > + .free = event_enable_trigger_free,
> > +};
> > +
> > +static struct event_trigger_ops hist_disable_trigger_ops = {
> > + .func = hist_enable_trigger,
> > + .print = event_enable_trigger_print,
> > + .init = event_trigger_init,
> > + .free = event_enable_trigger_free,
> > +};
> > +
> > +static struct event_trigger_ops hist_disable_count_trigger_ops = {
> > + .func = hist_enable_count_trigger,
> > + .print = event_enable_trigger_print,
> > + .init = event_trigger_init,
> > + .free = event_enable_trigger_free,
> > +};
> > +
> > +static struct event_trigger_ops *
> > +hist_enable_get_trigger_ops(char *cmd, char *param)
> > +{
> > + struct event_trigger_ops *ops;
> > + bool enable;
> > +
> > + enable = (strcmp(cmd, ENABLE_HIST_STR) == 0);
> > +
> > + if (enable)
> > + ops = param ? &hist_enable_count_trigger_ops :
> > + &hist_enable_trigger_ops;
> > + else
> > + ops = param ? &hist_disable_count_trigger_ops :
> > + &hist_disable_trigger_ops;
> > +
> > + return ops;
> > +}
> > +
> > +static struct event_command trigger_hist_enable_cmd = {
> > + .name = ENABLE_HIST_STR,
> > + .trigger_type = ETT_HIST_ENABLE,
> > + .func = event_enable_trigger_func,
> > + .reg = event_enable_register_trigger,
> > + .unreg = event_enable_unregister_trigger,
> > + .get_trigger_ops = hist_enable_get_trigger_ops,
> > + .set_filter = set_trigger_filter,
> > +};
> > +
> > +static struct event_command trigger_hist_disable_cmd = {
> > + .name = DISABLE_HIST_STR,
> > + .trigger_type = ETT_HIST_ENABLE,
> > + .func = event_enable_trigger_func,
> > + .reg = event_enable_register_trigger,
> > + .unreg = event_enable_unregister_trigger,
> > + .get_trigger_ops = hist_enable_get_trigger_ops,
> > + .set_filter = set_trigger_filter,
> > +};
> > +
> > +static __init void unregister_trigger_hist_enable_disable_cmds(void)
> > +{
> > + unregister_event_command(&trigger_hist_enable_cmd);
> > + unregister_event_command(&trigger_hist_disable_cmd);
> > +}
> > +
> > +__init int register_trigger_hist_enable_disable_cmds(void)
> > +{
> > + int ret;
> > +
> > + ret = register_event_command(&trigger_hist_enable_cmd);
> > + if (WARN_ON(ret < 0))
> > + return ret;
> > + ret = register_event_command(&trigger_hist_disable_cmd);
> > + if (WARN_ON(ret < 0))
> > + unregister_trigger_hist_enable_disable_cmds();
> > +
> > + return ret;
> > +}
> > diff --git a/kernel/trace/trace_events_trigger.c b/kernel/trace/trace_events_trigger.c
> > index e80f30b..9490d8f 100644
> > --- a/kernel/trace/trace_events_trigger.c
> > +++ b/kernel/trace/trace_events_trigger.c
> > @@ -338,7 +338,7 @@ __init int register_event_command(struct event_command *cmd)
> > * Currently we only unregister event commands from __init, so mark
> > * this __init too.
> > */
> > -static __init int unregister_event_command(struct event_command *cmd)
> > +__init int unregister_event_command(struct event_command *cmd)
> > {
> > struct event_command *p, *n;
> > int ret = -ENODEV;
> > @@ -1052,15 +1052,6 @@ static __init void unregister_trigger_traceon_traceoff_cmds(void)
> > unregister_event_command(&trigger_traceoff_cmd);
> > }
> >
> > -/* Avoid typos */
> > -#define ENABLE_EVENT_STR "enable_event"
> > -#define DISABLE_EVENT_STR "disable_event"
> > -
> > -struct enable_trigger_data {
> > - struct trace_event_file *file;
> > - bool enable;
> > -};
> > -
> > static void
> > event_enable_trigger(struct event_trigger_data *data, void *rec)
> > {
> > @@ -1090,14 +1081,16 @@ event_enable_count_trigger(struct event_trigger_data *data, void *rec)
> > event_enable_trigger(data, rec);
> > }
> >
> > -static int
> > -event_enable_trigger_print(struct seq_file *m, struct event_trigger_ops *ops,
> > - struct event_trigger_data *data)
> > +int event_enable_trigger_print(struct seq_file *m,
> > + struct event_trigger_ops *ops,
> > + struct event_trigger_data *data)
> > {
> > struct enable_trigger_data *enable_data = data->private_data;
> >
> > seq_printf(m, "%s:%s:%s",
> > - enable_data->enable ? ENABLE_EVENT_STR : DISABLE_EVENT_STR,
> > + enable_data->hist ?
> > + (enable_data->enable ? ENABLE_HIST_STR : DISABLE_HIST_STR) :
> > + (enable_data->enable ? ENABLE_EVENT_STR : DISABLE_EVENT_STR),
> > enable_data->file->event_call->class->system,
> > trace_event_name(enable_data->file->event_call));
> >
> > @@ -1114,9 +1107,8 @@ event_enable_trigger_print(struct seq_file *m, struct event_trigger_ops *ops,
> > return 0;
> > }
> >
> > -static void
> > -event_enable_trigger_free(struct event_trigger_ops *ops,
> > - struct event_trigger_data *data)
> > +void event_enable_trigger_free(struct event_trigger_ops *ops,
> > + struct event_trigger_data *data)
> > {
> > struct enable_trigger_data *enable_data = data->private_data;
> >
> > @@ -1161,10 +1153,9 @@ static struct event_trigger_ops event_disable_count_trigger_ops = {
> > .free = event_enable_trigger_free,
> > };
> >
> > -static int
> > -event_enable_trigger_func(struct event_command *cmd_ops,
> > - struct trace_event_file *file,
> > - char *glob, char *cmd, char *param)
> > +int event_enable_trigger_func(struct event_command *cmd_ops,
> > + struct trace_event_file *file,
> > + char *glob, char *cmd, char *param)
> > {
> > struct trace_event_file *event_enable_file;
> > struct enable_trigger_data *enable_data;
> > @@ -1173,6 +1164,7 @@ event_enable_trigger_func(struct event_command *cmd_ops,
> > struct trace_array *tr = file->tr;
> > const char *system;
> > const char *event;
> > + bool hist = false;
> > char *trigger;
> > char *number;
> > bool enable;
> > @@ -1197,8 +1189,15 @@ event_enable_trigger_func(struct event_command *cmd_ops,
> > if (!event_enable_file)
> > goto out;
> >
> > - enable = strcmp(cmd, ENABLE_EVENT_STR) == 0;
> > +#ifdef CONFIG_HIST_TRIGGERS
> > + hist = ((strcmp(cmd, ENABLE_HIST_STR) == 0) ||
> > + (strcmp(cmd, DISABLE_HIST_STR) == 0));
> >
> > + enable = ((strcmp(cmd, ENABLE_EVENT_STR) == 0) ||
> > + (strcmp(cmd, ENABLE_HIST_STR) == 0));
> > +#else
> > + enable = strcmp(cmd, ENABLE_EVENT_STR) == 0;
> > +#endif
> > trigger_ops = cmd_ops->get_trigger_ops(cmd, trigger);
> >
> > ret = -ENOMEM;
> > @@ -1218,6 +1217,7 @@ event_enable_trigger_func(struct event_command *cmd_ops,
> > INIT_LIST_HEAD(&trigger_data->list);
> > RCU_INIT_POINTER(trigger_data->filter, NULL);
> >
> > + enable_data->hist = hist;
> > enable_data->enable = enable;
> > enable_data->file = event_enable_file;
> > trigger_data->private_data = enable_data;
> > @@ -1295,10 +1295,10 @@ event_enable_trigger_func(struct event_command *cmd_ops,
> > goto out;
> > }
> >
> > -static int event_enable_register_trigger(char *glob,
> > - struct event_trigger_ops *ops,
> > - struct event_trigger_data *data,
> > - struct trace_event_file *file)
> > +int event_enable_register_trigger(char *glob,
> > + struct event_trigger_ops *ops,
> > + struct event_trigger_data *data,
> > + struct trace_event_file *file)
> > {
> > struct enable_trigger_data *enable_data = data->private_data;
> > struct enable_trigger_data *test_enable_data;
> > @@ -1308,6 +1308,8 @@ static int event_enable_register_trigger(char *glob,
> > list_for_each_entry_rcu(test, &file->triggers, list) {
> > test_enable_data = test->private_data;
> > if (test_enable_data &&
> > + (test->cmd_ops->trigger_type ==
> > + data->cmd_ops->trigger_type) &&
> > (test_enable_data->file == enable_data->file)) {
> > ret = -EEXIST;
> > goto out;
> > @@ -1333,10 +1335,10 @@ out:
> > return ret;
> > }
> >
> > -static void event_enable_unregister_trigger(char *glob,
> > - struct event_trigger_ops *ops,
> > - struct event_trigger_data *test,
> > - struct trace_event_file *file)
> > +void event_enable_unregister_trigger(char *glob,
> > + struct event_trigger_ops *ops,
> > + struct event_trigger_data *test,
> > + struct trace_event_file *file)
> > {
> > struct enable_trigger_data *test_enable_data = test->private_data;
> > struct enable_trigger_data *enable_data;
> > @@ -1346,6 +1348,8 @@ static void event_enable_unregister_trigger(char *glob,
> > list_for_each_entry_rcu(data, &file->triggers, list) {
> > enable_data = data->private_data;
> > if (enable_data &&
> > + (data->cmd_ops->trigger_type ==
> > + test->cmd_ops->trigger_type) &&
> > (enable_data->file == test_enable_data->file)) {
> > unregistered = true;
> > list_del_rcu(&data->list);
> > @@ -1365,8 +1369,12 @@ event_enable_get_trigger_ops(char *cmd, char *param)
> > struct event_trigger_ops *ops;
> > bool enable;
> >
> > +#ifdef CONFIG_HIST_TRIGGERS
> > + enable = ((strcmp(cmd, ENABLE_EVENT_STR) == 0) ||
> > + (strcmp(cmd, ENABLE_HIST_STR) == 0));
> > +#else
> > enable = strcmp(cmd, ENABLE_EVENT_STR) == 0;
> > -
> > +#endif
> > if (enable)
> > ops = param ? &event_enable_count_trigger_ops :
> > &event_enable_trigger_ops;
> > @@ -1437,6 +1445,7 @@ __init int register_trigger_cmds(void)
> > register_trigger_snapshot_cmd();
> > register_trigger_stacktrace_cmd();
> > register_trigger_enable_disable_cmds();
> > + register_trigger_hist_enable_disable_cmds();
> > register_trigger_hist_cmd();
> >
> > return 0;
> >
>
>
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