perf_counter: Add fork event

Create a fork event so that we can easily clone the comm and
dso maps without having to generate all those events.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/include/linux/perf_counter.h b/include/linux/perf_counter.h
index 37d5541..380247b 100644 (file)
--- a/include/linux/perf_counter.h
+++ b/include/linux/perf_counter.h
@@ -277,6 +277,14 @@ enum perf_event_type {
        PERF_EVENT_UNTHROTTLE           = 6,
 
        /*
+        * struct {
+        *      struct perf_event_header        header;
+        *      u32                             pid, ppid;
+        * };
+        */
+       PERF_EVENT_FORK                 = 7,
+
+       /*
         * When header.misc & PERF_EVENT_MISC_OVERFLOW the event_type field
         * will be PERF_RECORD_*
         *
@@ -618,6 +626,7 @@ extern void perf_counter_munmap(unsigned long addr, unsigned long len,
                                unsigned long pgoff, struct file *file);
 
 extern void perf_counter_comm(struct task_struct *tsk);
+extern void perf_counter_fork(struct task_struct *tsk);
 
 extern void perf_counter_task_migration(struct task_struct *task, int cpu);
 
@@ -673,6 +682,7 @@ perf_counter_munmap(unsigned long addr, unsigned long len,
                    unsigned long pgoff, struct file *file)             { }
 
 static inline void perf_counter_comm(struct task_struct *tsk)          { }
+static inline void perf_counter_fork(struct task_struct *tsk)          { }
 static inline void perf_counter_init(void)                             { }
 static inline void perf_counter_task_migration(struct task_struct *task,
                                               int cpu)                 { }

diff --git a/kernel/fork.c b/kernel/fork.c
index b7d7a9f..f4466ca 100644 (file)
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1412,12 +1412,12 @@ long do_fork(unsigned long clone_flags,
                if (clone_flags & CLONE_VFORK) {
                        p->vfork_done = &vfork;
                        init_completion(&vfork);
-               } else {
+               } else if (!(clone_flags & CLONE_VM)) {
                        /*
                         * vfork will do an exec which will call
                         * set_task_comm()
                         */
-                       perf_counter_comm(p);
+                       perf_counter_fork(p);
                }
 
                audit_finish_fork(p);

diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c
index 0bb03f1..78c5862 100644 (file)
--- a/kernel/perf_counter.c
+++ b/kernel/perf_counter.c
@@ -40,9 +40,9 @@ static int perf_reserved_percpu __read_mostly;
 static int perf_overcommit __read_mostly = 1;
 
 static atomic_t nr_counters __read_mostly;
-static atomic_t nr_mmap_tracking __read_mostly;
-static atomic_t nr_munmap_tracking __read_mostly;
-static atomic_t nr_comm_tracking __read_mostly;
+static atomic_t nr_mmap_counters __read_mostly;
+static atomic_t nr_munmap_counters __read_mostly;
+static atomic_t nr_comm_counters __read_mostly;
 
 int sysctl_perf_counter_priv __read_mostly; /* do we need to be privileged */
 int sysctl_perf_counter_mlock __read_mostly = 512; /* 'free' kb per user */
@@ -1447,11 +1447,11 @@ static void free_counter(struct perf_counter *counter)
 
        atomic_dec(&nr_counters);
        if (counter->attr.mmap)
-               atomic_dec(&nr_mmap_tracking);
+               atomic_dec(&nr_mmap_counters);
        if (counter->attr.munmap)
-               atomic_dec(&nr_munmap_tracking);
+               atomic_dec(&nr_munmap_counters);
        if (counter->attr.comm)
-               atomic_dec(&nr_comm_tracking);
+               atomic_dec(&nr_comm_counters);
 
        if (counter->destroy)
                counter->destroy(counter);
@@ -2476,6 +2476,105 @@ static void perf_counter_output(struct perf_counter *counter,
 }
 
 /*
+ * fork tracking
+ */
+
+struct perf_fork_event {
+       struct task_struct      *task;
+
+       struct {
+               struct perf_event_header        header;
+
+               u32                             pid;
+               u32                             ppid;
+       } event;
+};
+
+static void perf_counter_fork_output(struct perf_counter *counter,
+                                    struct perf_fork_event *fork_event)
+{
+       struct perf_output_handle handle;
+       int size = fork_event->event.header.size;
+       struct task_struct *task = fork_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);
+
+       perf_output_put(&handle, fork_event->event);
+       perf_output_end(&handle);
+}
+
+static int perf_counter_fork_match(struct perf_counter *counter)
+{
+       if (counter->attr.comm || counter->attr.mmap || counter->attr.munmap)
+               return 1;
+
+       return 0;
+}
+
+static void perf_counter_fork_ctx(struct perf_counter_context *ctx,
+                                 struct perf_fork_event *fork_event)
+{
+       struct perf_counter *counter;
+
+       if (system_state != SYSTEM_RUNNING || list_empty(&ctx->event_list))
+               return;
+
+       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);
+       }
+       rcu_read_unlock();
+}
+
+static void perf_counter_fork_event(struct perf_fork_event *fork_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);
+       put_cpu_var(perf_cpu_context);
+
+       rcu_read_lock();
+       /*
+        * doesn't really matter which of the child contexts the
+        * events ends up in.
+        */
+       ctx = rcu_dereference(current->perf_counter_ctxp);
+       if (ctx)
+               perf_counter_fork_ctx(ctx, fork_event);
+       rcu_read_unlock();
+}
+
+void perf_counter_fork(struct task_struct *task)
+{
+       struct perf_fork_event fork_event;
+
+       if (!atomic_read(&nr_comm_counters) &&
+           !atomic_read(&nr_mmap_counters) &&
+           !atomic_read(&nr_munmap_counters))
+               return;
+
+       fork_event = (struct perf_fork_event){
+               .task   = task,
+               .event  = {
+                       .header = {
+                               .type = PERF_EVENT_FORK,
+                               .size = sizeof(fork_event.event),
+                       },
+               },
+       };
+
+       perf_counter_fork_event(&fork_event);
+}
+
+/*
  * comm tracking
  */
 
@@ -2511,11 +2610,9 @@ static void perf_counter_comm_output(struct perf_counter *counter,
        perf_output_end(&handle);
 }
 
-static int perf_counter_comm_match(struct perf_counter *counter,
-                                  struct perf_comm_event *comm_event)
+static int perf_counter_comm_match(struct perf_counter *counter)
 {
-       if (counter->attr.comm &&
-           comm_event->event.header.type == PERF_EVENT_COMM)
+       if (counter->attr.comm)
                return 1;
 
        return 0;
@@ -2531,7 +2628,7 @@ static void perf_counter_comm_ctx(struct perf_counter_context *ctx,
 
        rcu_read_lock();
        list_for_each_entry_rcu(counter, &ctx->event_list, event_entry) {
-               if (perf_counter_comm_match(counter, comm_event))
+               if (perf_counter_comm_match(counter))
                        perf_counter_comm_output(counter, comm_event);
        }
        rcu_read_unlock();
@@ -2570,7 +2667,7 @@ void perf_counter_comm(struct task_struct *task)
 {
        struct perf_comm_event comm_event;
 
-       if (!atomic_read(&nr_comm_tracking))
+       if (!atomic_read(&nr_comm_counters))
                return;
 
        comm_event = (struct perf_comm_event){
@@ -2708,7 +2805,7 @@ void perf_counter_mmap(unsigned long addr, unsigned long len,
 {
        struct perf_mmap_event mmap_event;
 
-       if (!atomic_read(&nr_mmap_tracking))
+       if (!atomic_read(&nr_mmap_counters))
                return;
 
        mmap_event = (struct perf_mmap_event){
@@ -2729,7 +2826,7 @@ void perf_counter_munmap(unsigned long addr, unsigned long len,
 {
        struct perf_mmap_event mmap_event;
 
-       if (!atomic_read(&nr_munmap_tracking))
+       if (!atomic_read(&nr_munmap_counters))
                return;
 
        mmap_event = (struct perf_mmap_event){
@@ -3427,11 +3524,11 @@ done:
 
        atomic_inc(&nr_counters);
        if (counter->attr.mmap)
-               atomic_inc(&nr_mmap_tracking);
+               atomic_inc(&nr_mmap_counters);
        if (counter->attr.munmap)
-               atomic_inc(&nr_munmap_tracking);
+               atomic_inc(&nr_munmap_counters);
        if (counter->attr.comm)
-               atomic_inc(&nr_comm_tracking);
+               atomic_inc(&nr_comm_counters);
 
        return counter;
 }