[tip:perf/core] perf sched: Add -C option to measure on a specific CPU

tip-bot for Mike Galbraith
2009-10-12T07:14:12Z

Commit-ID: 55ffb7a6bd45d0083ffb132381cb46964a4afe01
Gitweb: http://git.kernel.org/tip/55ffb7a6bd45d0083ffb132381cb46964a4afe01
Author: Mike Galbraith <efault@gmx.de>
AuthorDate: Sat, 10 Oct 2009 14:46:04 +0200
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Mon, 12 Oct 2009 09:10:55 +0200

perf sched: Add -C option to measure on a specific CPU

To refresh, trying to sched record only one CPU results in bogus
latencies as below.

I fixed^Wmade it stop doing the bad thing today, by
following task migration events properly.

Before:

marge:/root/tmp # taskset -c 1 perf sched record -C 0 -- sleep 10
marge:/root/tmp # perf sched lat
-----------------------------------------------------------------------------------------
Task | Runtime ms | Switches | Average delay ms | Maximum delay ms |
-----------------------------------------------------------------------------------------
Xorg:4943 | 1.290 ms | 1 | avg: 1670.132 ms | max: 1670.132 ms |
hald-addon-stor:3569 | 0.091 ms | 3 | avg: 658.609 ms | max: 1975.797 ms |
hald-addon-stor:3573 | 0.209 ms | 4 | avg: 499.138 ms | max: 1990.565 ms |
audispd:4270 | 0.012 ms | 1 | avg: 0.015 ms | max: 0.015 ms |
....

marge:/root/tmp # perf sched trace|grep 'Xorg:4943'
swapper-0 [000] 401.184013288: sched_stat_runtime: task: Xorg:4943 runtime: 1233188 [ns], vruntime: 19105169779 [ns]
rt2870TimerQHan-4947 [000] 402.854140127: sched_stat_wait: task: Xorg:4943 wait: 580073 [ns]
rt2870TimerQHan-4947 [000] 402.854141770: sched_migrate_task: task Xorg:4943 [140] from: 1 to: 0
rt2870TimerQHan-4947 [000] 402.854143854: sched_stat_wait: task: Xorg:4943 wait: 0 [ns]
rt2870TimerQHan-4947 [000] 402.854145397: sched_switch: task rt2870TimerQHan:4947 [140] (D) ==> Xorg:4943 [140]
Xorg-4943 [000] 402.854193133: sched_stat_runtime: task: Xorg:4943 runtime: 56546 [ns], vruntime: 11766332500 [ns]
Xorg-4943 [000] 402.854196842: sched_switch: task Xorg:4943 [140] (S) ==> swapper:0 [140]

After:

marge:/root/tmp # taskset -c 1 perf sched record -C 0 -- sleep 10
marge:/root/tmp # perf sched lat
-----------------------------------------------------------------------------------------
Task | Runtime ms | Switches | Average delay ms | Maximum delay ms |
-----------------------------------------------------------------------------------------
amarokapp:11150 | 271.297 ms | 878 | avg: 0.130 ms | max: 1.057 ms |
konsole:5965 | 1.370 ms | 12 | avg: 0.092 ms | max: 0.855 ms |
Xorg:4943 | 179.980 ms | 1109 | avg: 0.087 ms | max: 1.206 ms |
hald-addon-stor:3574 | 0.212 ms | 9 | avg: 0.040 ms | max: 0.169 ms |
hald-addon-stor:3570 | 0.223 ms | 9 | avg: 0.037 ms | max: 0.223 ms |
klauncher:5864 | 0.550 ms | 8 | avg: 0.032 ms | max: 0.048 ms |

The 'Maximum delay ms' results are now sane.

Signed-off-by: Mike Galbraith <efault@gmx.de>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
tools/perf/builtin-sched.c | 101 +++++++++++++++++++++++++++++++++++++++++++-
1 files changed, 100 insertions(+), 1 deletions(-)

diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c
index 6b00529..387a442 100644
--- a/tools/perf/builtin-sched.c
+++ b/tools/perf/builtin-sched.c
@@ -33,6 +33,8 @@ static u64 sample_type;
static char default_sort_order[] = "avg, max, switch, runtime";
static char *sort_order = default_sort_order;

+static int profile_cpu = -1;
+
static char *cwd;
static int cwdlen;

@@ -75,6 +77,7 @@ enum sched_event_type {
SCHED_EVENT_RUN,
SCHED_EVENT_SLEEP,
SCHED_EVENT_WAKEUP,
+ SCHED_EVENT_MIGRATION,
};

struct sched_atom {
@@ -399,6 +402,8 @@ process_sched_event(struct task_desc *this_task __used, struct sched_atom *atom)
ret = sem_post(atom->wait_sem);
BUG_ON(ret);
break;
+ case SCHED_EVENT_MIGRATION:
+ break;
default:
BUG_ON(1);
}
@@ -746,6 +751,22 @@ struct trace_fork_event {
u32 child_pid;
};

+struct trace_migrate_task_event {
+ u32 size;
+
+ u16 common_type;
+ u8 common_flags;
+ u8 common_preempt_count;
+ u32 common_pid;
+ u32 common_tgid;
+
+ char comm[16];
+ u32 pid;
+
+ u32 prio;
+ u32 cpu;
+};
+
struct trace_sched_handler {
void (*switch_event)(struct trace_switch_event *,
struct event *,
@@ -770,6 +791,12 @@ struct trace_sched_handler {
int cpu,
u64 timestamp,
struct thread *thread);
+
+ void (*migrate_task_event)(struct trace_migrate_task_event *,
+ struct event *,
+ int cpu,
+ u64 timestamp,
+ struct thread *thread);
};

@@ -1140,7 +1167,12 @@ latency_wakeup_event(struct trace_wakeup_event *wakeup_event,

atom = list_entry(atoms->work_list.prev, struct work_atom, list);

- if (atom->state != THREAD_SLEEPING)
+ /*
+ * You WILL be missing events if you've recorded only
+ * one CPU, or are only looking at only one, so don't
+ * make useless noise.
+ */
+ if (profile_cpu == -1 && atom->state != THREAD_SLEEPING)
nr_state_machine_bugs++;

nr_timestamps++;
@@ -1153,11 +1185,51 @@ latency_wakeup_event(struct trace_wakeup_event *wakeup_event,
atom->wake_up_time = timestamp;
}

+static void
+latency_migrate_task_event(struct trace_migrate_task_event *migrate_task_event,
+ struct event *__event __used,
+ int cpu __used,
+ u64 timestamp,
+ struct thread *thread __used)
+{
+ struct work_atoms *atoms;
+ struct work_atom *atom;
+ struct thread *migrant;
+
+ /*
+ * Only need to worry about migration when profiling one CPU.
+ */
+ if (profile_cpu == -1)
+ return;
+
+ migrant = threads__findnew(migrate_task_event->pid, &threads, &last_match);
+ atoms = thread_atoms_search(&atom_root, migrant, &cmp_pid);
+ if (!atoms) {
+ thread_atoms_insert(migrant);
+ register_pid(migrant->pid, migrant->comm);
+ atoms = thread_atoms_search(&atom_root, migrant, &cmp_pid);
+ if (!atoms)
+ die("migration-event: Internal tree error");
+ add_sched_out_event(atoms, 'R', timestamp);
+ }
+
+ BUG_ON(list_empty(&atoms->work_list));
+
+ atom = list_entry(atoms->work_list.prev, struct work_atom, list);
+ atom->sched_in_time = atom->sched_out_time = atom->wake_up_time = timestamp;
+
+ nr_timestamps++;
+
+ if (atom->sched_out_time > timestamp)
+ nr_unordered_timestamps++;
+}
+
static struct trace_sched_handler lat_ops = {
.wakeup_event = latency_wakeup_event,
.switch_event = latency_switch_event,
.runtime_event = latency_runtime_event,
.fork_event = latency_fork_event,
+ .migrate_task_event = latency_migrate_task_event,
};

static void output_lat_thread(struct work_atoms *work_list)
@@ -1518,6 +1590,26 @@ process_sched_exit_event(struct event *event,
}

static void
+process_sched_migrate_task_event(struct raw_event_sample *raw,
+ struct event *event,
+ int cpu __used,
+ u64 timestamp __used,
+ struct thread *thread __used)
+{
+ struct trace_migrate_task_event migrate_task_event;
+
+ FILL_COMMON_FIELDS(migrate_task_event, event, raw->data);
+
+ FILL_ARRAY(migrate_task_event, comm, event, raw->data);
+ FILL_FIELD(migrate_task_event, pid, event, raw->data);
+ FILL_FIELD(migrate_task_event, prio, event, raw->data);
+ FILL_FIELD(migrate_task_event, cpu, event, raw->data);
+
+ if (trace_handler->migrate_task_event)
+ trace_handler->migrate_task_event(&migrate_task_event, event, cpu, timestamp, thread);
+}
+
+static void
process_raw_event(event_t *raw_event __used, void *more_data,
int cpu, u64 timestamp, struct thread *thread)
{
@@ -1540,6 +1632,8 @@ process_raw_event(event_t *raw_event __used, void *more_data,
process_sched_fork_event(raw, event, cpu, timestamp, thread);
if (!strcmp(event->name, "sched_process_exit"))
process_sched_exit_event(event, cpu, timestamp, thread);
+ if (!strcmp(event->name, "sched_migrate_task"))
+ process_sched_migrate_task_event(raw, event, cpu, timestamp, thread);
}

static int
@@ -1589,6 +1683,9 @@ process_sample_event(event_t *event, unsigned long offset, unsigned long head)
return -1;
}

+ if (profile_cpu != -1 && profile_cpu != (int) cpu)
+ return 0;
+
process_raw_event(event, more_data, cpu, timestamp, thread);

return 0;
@@ -1771,6 +1868,8 @@ static const struct option latency_options[] = {
"sort by key(s): runtime, switch, avg, max"),
OPT_BOOLEAN('v', "verbose", &verbose,
"be more verbose (show symbol address, etc)"),
+ OPT_INTEGER('C', "CPU", &profile_cpu,
+ "CPU to profile on"),
OPT_BOOLEAN('D', "dump-raw-trace", &dump_trace,
"dump raw trace in ASCII"),
OPT_END()