Re: [PATCH 2/3] perf tools: Allow to enable/disable events via control file

Arnaldo Carvalho de Melo
2020-12-15T15:15:04Z

Em Thu, Dec 10, 2020 at 09:43:29PM +0100, Jiri Olsa escreveu:
> Adding new control events to enable/disable specific event.
> The interface string for control file are:
>
> 'enable-<EVENT NAME>'
> 'disable-<EVENT NAME>'

Wwy do we have "enable-" as the "tag" for this?

Also is it possible to use "enable sched:*" and have that match what is
in the evlist and enable (or disable, if using "disable sched:*") what
matches?

This second suggestion can be done on top of this, i.e. as an
enhancement, but mixing up the command (enable, disable) with its
arguments looks strange.

- Arnaldo

> when received the command, perf will scan the current evlist
> for <EVENT NAME> and if found it's enabled/disabled.
>
> Example session:
>
> terminal 1:
> # mkfifo control ack perf.pipe
> # perf record --control=fifo:control,ack -D -1 --no-buffering -e 'sched:*' -o - > perf.pipe
> Events disabled
>
> terminal 2:
> # cat perf.pipe | ./perf --no-pager script -i -
>
> terminal 3:
> # echo enable-sched:sched_process_fork > control
>
> terminal 1:
> # mkfifo control ack perf.pipe
> # perf record --control=fifo:control,ack -D -1 --no-buffering -e 'sched:*' -o - > perf.pipe
> ...
> event sched:sched_process_fork enabled
>
> terminal 2:
> # cat perf.pipe | ./perf --no-pager script -i -
> bash 33349 [034] 149587.674295: sched:sched_process_fork: comm=bash pid=33349 child_comm=bash child_pid=34056
> bash 33349 [034] 149588.239521: sched:sched_process_fork: comm=bash pid=33349 child_comm=bash child_pid=34057
>
> terminal 3:
> # echo enable-sched:sched_wakeup_new > control
>
> terminal 1:
> # mkfifo control ack perf.pipe
> # perf record --control=fifo:control,ack -D -1 --no-buffering -e 'sched:*' -o - > perf.pipe
> ...
> event sched:sched_wakeup_new enabled
>
> terminal 2:
> # cat perf.pipe | ./perf --no-pager script -i -
> ...
> bash 33349 [034] 149632.228023: sched:sched_process_fork: comm=bash pid=33349 child_comm=bash child_pid=34059
> bash 33349 [034] 149632.228050: sched:sched_wakeup_new: bash:34059 [120] success=1 CPU:036
> bash 33349 [034] 149633.950005: sched:sched_process_fork: comm=bash pid=33349 child_comm=bash child_pid=34060
> bash 33349 [034] 149633.950030: sched:sched_wakeup_new: bash:34060 [120] success=1 CPU:036
>
> Acked-by: Namhyung Kim <namhyung@kernel.org>
> Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> ---
> tools/perf/builtin-record.c | 2 ++
> tools/perf/builtin-stat.c | 2 ++
> tools/perf/util/evlist.c | 30 +++++++++++++++++++++++++++++-
> tools/perf/util/evlist.h | 4 ++++
> 4 files changed, 37 insertions(+), 1 deletion(-)
>
> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
> index d832c108a1ca..582b8fba012c 100644
> --- a/tools/perf/builtin-record.c
> +++ b/tools/perf/builtin-record.c
> @@ -1949,6 +1949,8 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
> break;
> case EVLIST_CTL_CMD_ACK:
> case EVLIST_CTL_CMD_UNSUPPORTED:
> + case EVLIST_CTL_CMD_ENABLE_EVSEL:
> + case EVLIST_CTL_CMD_DISABLE_EVSEL:
> default:
> break;
> }
> diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
> index 89c32692f40c..6a21fb665008 100644
> --- a/tools/perf/builtin-stat.c
> +++ b/tools/perf/builtin-stat.c
> @@ -590,6 +590,8 @@ static void process_evlist(struct evlist *evlist, unsigned int interval)
> case EVLIST_CTL_CMD_SNAPSHOT:
> case EVLIST_CTL_CMD_ACK:
> case EVLIST_CTL_CMD_UNSUPPORTED:
> + case EVLIST_CTL_CMD_ENABLE_EVSEL:
> + case EVLIST_CTL_CMD_DISABLE_EVSEL:
> default:
> break;
> }
> diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
> index 70aff26612a9..729c98d10628 100644
> --- a/tools/perf/util/evlist.c
> +++ b/tools/perf/util/evlist.c
> @@ -1915,7 +1915,13 @@ static int evlist__ctlfd_recv(struct evlist *evlist, enum evlist_ctl_cmd *cmd,
> bytes_read == data_size ? "" : c == '\n' ? "\\n" : "\\0");
>
> if (bytes_read > 0) {
> - if (!strncmp(cmd_data, EVLIST_CTL_CMD_ENABLE_TAG,
> + if (!strncmp(cmd_data, EVLIST_CTL_CMD_ENABLE_EVSEL_TAG,
> + (sizeof(EVLIST_CTL_CMD_ENABLE_EVSEL_TAG)-1))) {
> + *cmd = EVLIST_CTL_CMD_ENABLE_EVSEL;
> + } else if (!strncmp(cmd_data, EVLIST_CTL_CMD_DISABLE_EVSEL_TAG,
> + (sizeof(EVLIST_CTL_CMD_DISABLE_EVSEL_TAG)-1))) {
> + *cmd = EVLIST_CTL_CMD_DISABLE_EVSEL;
> + } else if (!strncmp(cmd_data, EVLIST_CTL_CMD_ENABLE_TAG,
> (sizeof(EVLIST_CTL_CMD_ENABLE_TAG)-1))) {
> *cmd = EVLIST_CTL_CMD_ENABLE;
> } else if (!strncmp(cmd_data, EVLIST_CTL_CMD_DISABLE_TAG,
> @@ -1952,6 +1958,8 @@ int evlist__ctlfd_process(struct evlist *evlist, enum evlist_ctl_cmd *cmd)
> char cmd_data[EVLIST_CTL_CMD_MAX_LEN];
> int ctlfd_pos = evlist->ctl_fd.pos;
> struct pollfd *entries = evlist->core.pollfd.entries;
> + struct evsel *evsel;
> + char *evsel_name;
>
> if (!evlist__ctlfd_initialized(evlist) || !entries[ctlfd_pos].revents)
> return 0;
> @@ -1967,6 +1975,26 @@ int evlist__ctlfd_process(struct evlist *evlist, enum evlist_ctl_cmd *cmd)
> case EVLIST_CTL_CMD_DISABLE:
> evlist__disable(evlist);
> break;
> + case EVLIST_CTL_CMD_ENABLE_EVSEL:
> + evsel_name = cmd_data + sizeof(EVLIST_CTL_CMD_ENABLE_EVSEL_TAG) - 1;
> + evsel = evlist__find_evsel_by_str(evlist, evsel_name);
> + if (evsel) {
> + evlist__enable_evsel(evlist, evsel_name);
> + pr_info("event %s enabled\n", evsel->name);
> + } else {
> + pr_info("failed: can't find '%s' event\n", evsel_name);
> + }
> + break;
> + case EVLIST_CTL_CMD_DISABLE_EVSEL:
> + evsel_name = cmd_data + sizeof(EVLIST_CTL_CMD_DISABLE_EVSEL_TAG) - 1;
> + evsel = evlist__find_evsel_by_str(evlist, evsel_name);
> + if (evsel) {
> + evlist__disable_evsel(evlist, evsel_name);
> + pr_info("event %s disabled\n", evsel->name);
> + } else {
> + pr_info("failed: can't find '%s' event\n", evsel_name);
> + }
> + break;
> case EVLIST_CTL_CMD_SNAPSHOT:
> break;
> case EVLIST_CTL_CMD_ACK:
> diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h
> index 1aae75895dea..e4e8ff8831a3 100644
> --- a/tools/perf/util/evlist.h
> +++ b/tools/perf/util/evlist.h
> @@ -330,6 +330,8 @@ struct evsel *evlist__reset_weak_group(struct evlist *evlist, struct evsel *evse
> #define EVLIST_CTL_CMD_DISABLE_TAG "disable"
> #define EVLIST_CTL_CMD_ACK_TAG "ack\n"
> #define EVLIST_CTL_CMD_SNAPSHOT_TAG "snapshot"
> +#define EVLIST_CTL_CMD_ENABLE_EVSEL_TAG "enable-"
> +#define EVLIST_CTL_CMD_DISABLE_EVSEL_TAG "disable-"
>
> #define EVLIST_CTL_CMD_MAX_LEN 64
>
> @@ -337,6 +339,8 @@ enum evlist_ctl_cmd {
> EVLIST_CTL_CMD_UNSUPPORTED = 0,
> EVLIST_CTL_CMD_ENABLE,
> EVLIST_CTL_CMD_DISABLE,
> + EVLIST_CTL_CMD_ENABLE_EVSEL,
> + EVLIST_CTL_CMD_DISABLE_EVSEL,
> EVLIST_CTL_CMD_ACK,
> EVLIST_CTL_CMD_SNAPSHOT,
> };
> --
> 2.26.2
>

--

- Arnaldo