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

Jiri Olsa
2020-12-06T17:06:46Z

Adding new control events to enable/disable specific event.
The interface string for control file are:

'enable-<EVENT NAME>'
'disable-<EVENT NAME>'

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

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..05723227bebf 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