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authorPeter Zijlstra <a.p.zijlstra@chello.nl>2009-07-23 14:46:33 +0200
committerIngo Molnar <mingo@elte.hu>2009-08-02 13:47:56 +0200
commit9f498cc5be7e013d8d6e4c616980ed0ffc8680d2 (patch)
tree25ef7a52d61ffd336c73b42dcf770424beb19cf3
parente53c0994709166b111fbe9162d1a16ece7dfc45b (diff)
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perf_counter: Full task tracing
In order to be able to distinguish between no samples due to inactivity and no samples due to task ended, Arjan asked for PERF_EVENT_EXIT events. This is useful to the boot delay instrumentation (bootchart) app. This patch changes the PERF_EVENT_FORK to be emitted on every clone, and adds PERF_EVENT_EXIT to be emitted on task exit, after the task's counters have been closed. This task tracing is controlled through: attr.comm || attr.mmap and through the new attr.task field. Suggested-by: Arjan van de Ven <arjan@linux.intel.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Anton Blanchard <anton@samba.org> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> [ cleaned up perf_counter.h a bit ] Signed-off-by: Ingo Molnar <mingo@elte.hu>
-rw-r--r--include/linux/perf_counter.h13
-rw-r--r--kernel/fork.c4
-rw-r--r--kernel/perf_counter.c87
3 files changed, 71 insertions, 33 deletions
diff --git a/include/linux/perf_counter.h b/include/linux/perf_counter.h
index bd15d7a5f5ce..e604e6ef72dd 100644
--- a/include/linux/perf_counter.h
+++ b/include/linux/perf_counter.h
@@ -181,8 +181,9 @@ struct perf_counter_attr {
freq : 1, /* use freq, not period */
inherit_stat : 1, /* per task counts */
enable_on_exec : 1, /* next exec enables */
+ task : 1, /* trace fork/exit */
- __reserved_1 : 51;
+ __reserved_1 : 50;
__u32 wakeup_events; /* wakeup every n events */
__u32 __reserved_2;
@@ -311,6 +312,15 @@ enum perf_event_type {
/*
* struct {
* struct perf_event_header header;
+ * u32 pid, ppid;
+ * u32 tid, ptid;
+ * };
+ */
+ PERF_EVENT_EXIT = 4,
+
+ /*
+ * struct {
+ * struct perf_event_header header;
* u64 time;
* u64 id;
* u64 stream_id;
@@ -323,6 +333,7 @@ enum perf_event_type {
* struct {
* struct perf_event_header header;
* u32 pid, ppid;
+ * u32 tid, ptid;
* };
*/
PERF_EVENT_FORK = 7,
diff --git a/kernel/fork.c b/kernel/fork.c
index 29b532e718f7..466531eb92cc 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1269,6 +1269,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
write_unlock_irq(&tasklist_lock);
proc_fork_connector(p);
cgroup_post_fork(p);
+ perf_counter_fork(p);
return p;
bad_fork_free_pid:
@@ -1410,9 +1411,6 @@ long do_fork(unsigned long clone_flags,
init_completion(&vfork);
}
- if (!(clone_flags & CLONE_THREAD))
- perf_counter_fork(p);
-
audit_finish_fork(p);
tracehook_report_clone(regs, clone_flags, nr, p);
diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c
index 48471d75ae01..199ed4771315 100644
--- a/kernel/perf_counter.c
+++ b/kernel/perf_counter.c
@@ -42,6 +42,7 @@ static int perf_overcommit __read_mostly = 1;
static atomic_t nr_counters __read_mostly;
static atomic_t nr_mmap_counters __read_mostly;
static atomic_t nr_comm_counters __read_mostly;
+static atomic_t nr_task_counters __read_mostly;
/*
* perf counter paranoia level:
@@ -1654,6 +1655,8 @@ static void free_counter(struct perf_counter *counter)
atomic_dec(&nr_mmap_counters);
if (counter->attr.comm)
atomic_dec(&nr_comm_counters);
+ if (counter->attr.task)
+ atomic_dec(&nr_task_counters);
}
if (counter->destroy)
@@ -2831,10 +2834,12 @@ perf_counter_read_event(struct perf_counter *counter,
}
/*
- * fork tracking
+ * task tracking -- fork/exit
+ *
+ * enabled by: attr.comm | attr.mmap | attr.task
*/
-struct perf_fork_event {
+struct perf_task_event {
struct task_struct *task;
struct {
@@ -2842,37 +2847,42 @@ struct perf_fork_event {
u32 pid;
u32 ppid;
+ u32 tid;
+ u32 ptid;
} event;
};
-static void perf_counter_fork_output(struct perf_counter *counter,
- struct perf_fork_event *fork_event)
+static void perf_counter_task_output(struct perf_counter *counter,
+ struct perf_task_event *task_event)
{
struct perf_output_handle handle;
- int size = fork_event->event.header.size;
- struct task_struct *task = fork_event->task;
+ int size = task_event->event.header.size;
+ struct task_struct *task = task_event->task;
int ret = perf_output_begin(&handle, counter, size, 0, 0);
if (ret)
return;
- fork_event->event.pid = perf_counter_pid(counter, task);
- fork_event->event.ppid = perf_counter_pid(counter, task->real_parent);
+ task_event->event.pid = perf_counter_pid(counter, task);
+ task_event->event.ppid = perf_counter_pid(counter, task->real_parent);
- perf_output_put(&handle, fork_event->event);
+ task_event->event.tid = perf_counter_tid(counter, task);
+ task_event->event.ptid = perf_counter_tid(counter, task->real_parent);
+
+ perf_output_put(&handle, task_event->event);
perf_output_end(&handle);
}
-static int perf_counter_fork_match(struct perf_counter *counter)
+static int perf_counter_task_match(struct perf_counter *counter)
{
- if (counter->attr.comm || counter->attr.mmap)
+ if (counter->attr.comm || counter->attr.mmap || counter->attr.task)
return 1;
return 0;
}
-static void perf_counter_fork_ctx(struct perf_counter_context *ctx,
- struct perf_fork_event *fork_event)
+static void perf_counter_task_ctx(struct perf_counter_context *ctx,
+ struct perf_task_event *task_event)
{
struct perf_counter *counter;
@@ -2881,19 +2891,19 @@ static void perf_counter_fork_ctx(struct perf_counter_context *ctx,
rcu_read_lock();
list_for_each_entry_rcu(counter, &ctx->event_list, event_entry) {
- if (perf_counter_fork_match(counter))
- perf_counter_fork_output(counter, fork_event);
+ if (perf_counter_task_match(counter))
+ perf_counter_task_output(counter, task_event);
}
rcu_read_unlock();
}
-static void perf_counter_fork_event(struct perf_fork_event *fork_event)
+static void perf_counter_task_event(struct perf_task_event *task_event)
{
struct perf_cpu_context *cpuctx;
struct perf_counter_context *ctx;
cpuctx = &get_cpu_var(perf_cpu_context);
- perf_counter_fork_ctx(&cpuctx->ctx, fork_event);
+ perf_counter_task_ctx(&cpuctx->ctx, task_event);
put_cpu_var(perf_cpu_context);
rcu_read_lock();
@@ -2903,32 +2913,40 @@ static void perf_counter_fork_event(struct perf_fork_event *fork_event)
*/
ctx = rcu_dereference(current->perf_counter_ctxp);
if (ctx)
- perf_counter_fork_ctx(ctx, fork_event);
+ perf_counter_task_ctx(ctx, task_event);
rcu_read_unlock();
}
-void perf_counter_fork(struct task_struct *task)
+static void perf_counter_task(struct task_struct *task, int new)
{
- struct perf_fork_event fork_event;
+ struct perf_task_event task_event;
if (!atomic_read(&nr_comm_counters) &&
- !atomic_read(&nr_mmap_counters))
+ !atomic_read(&nr_mmap_counters) &&
+ !atomic_read(&nr_task_counters))
return;
- fork_event = (struct perf_fork_event){
+ task_event = (struct perf_task_event){
.task = task,
.event = {
.header = {
- .type = PERF_EVENT_FORK,
+ .type = new ? PERF_EVENT_FORK : PERF_EVENT_EXIT,
.misc = 0,
- .size = sizeof(fork_event.event),
+ .size = sizeof(task_event.event),
},
/* .pid */
/* .ppid */
+ /* .tid */
+ /* .ptid */
},
};
- perf_counter_fork_event(&fork_event);
+ perf_counter_task_event(&task_event);
+}
+
+void perf_counter_fork(struct task_struct *task)
+{
+ perf_counter_task(task, 1);
}
/*
@@ -3887,6 +3905,8 @@ done:
atomic_inc(&nr_mmap_counters);
if (counter->attr.comm)
atomic_inc(&nr_comm_counters);
+ if (counter->attr.task)
+ atomic_inc(&nr_task_counters);
}
return counter;
@@ -4248,8 +4268,10 @@ void perf_counter_exit_task(struct task_struct *child)
struct perf_counter_context *child_ctx;
unsigned long flags;
- if (likely(!child->perf_counter_ctxp))
+ if (likely(!child->perf_counter_ctxp)) {
+ perf_counter_task(child, 0);
return;
+ }
local_irq_save(flags);
/*
@@ -4267,15 +4289,22 @@ void perf_counter_exit_task(struct task_struct *child)
* incremented the context's refcount before we do put_ctx below.
*/
spin_lock(&child_ctx->lock);
- child->perf_counter_ctxp = NULL;
/*
* If this context is a clone; unclone it so it can't get
* swapped to another process while we're removing all
* the counters from it.
*/
unclone_ctx(child_ctx);
- spin_unlock(&child_ctx->lock);
- local_irq_restore(flags);
+ spin_unlock_irqrestore(&child_ctx->lock, flags);
+
+ /*
+ * Report the task dead after unscheduling the counters so that we
+ * won't get any samples after PERF_EVENT_EXIT. We can however still
+ * get a few PERF_EVENT_READ events.
+ */
+ perf_counter_task(child, 0);
+
+ child->perf_counter_ctxp = NULL;
/*
* We can recurse on the same lock type through: