perf, trace: Optimize tracepoints by using per-tracepoint-per-cpu hlist to track events
Avoid the swevent hash-table by using per-tracepoint
hlists.
Also, avoid conditionals on the fast path by ordering
with probe unregister so that we should never get on
the callback path without the data being there.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <20100521090710.473188012@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c
index a1304f8..39d5ea7 100644
--- a/kernel/trace/trace_event_perf.c
+++ b/kernel/trace/trace_event_perf.c
@@ -23,14 +23,25 @@
/* Count the events in use (per event id, not per instance) */
static int total_ref_count;
-static int perf_trace_event_enable(struct ftrace_event_call *event, void *data)
+static int perf_trace_event_init(struct ftrace_event_call *tp_event,
+ struct perf_event *p_event)
{
+ struct hlist_head *list;
int ret = -ENOMEM;
+ int cpu;
- if (event->perf_refcount++ > 0) {
- event->perf_data = NULL;
+ p_event->tp_event = tp_event;
+ if (tp_event->perf_refcount++ > 0)
return 0;
- }
+
+ list = alloc_percpu(struct hlist_head);
+ if (!list)
+ goto fail;
+
+ for_each_possible_cpu(cpu)
+ INIT_HLIST_HEAD(per_cpu_ptr(list, cpu));
+
+ tp_event->perf_events = list;
if (!total_ref_count) {
char *buf;
@@ -39,20 +50,20 @@
for (i = 0; i < 4; i++) {
buf = (char *)alloc_percpu(perf_trace_t);
if (!buf)
- goto fail_buf;
+ goto fail;
- rcu_assign_pointer(perf_trace_buf[i], buf);
+ perf_trace_buf[i] = buf;
}
}
- ret = event->perf_event_enable(event);
- if (!ret) {
- event->perf_data = data;
- total_ref_count++;
- return 0;
- }
+ ret = tp_event->perf_event_enable(tp_event);
+ if (ret)
+ goto fail;
-fail_buf:
+ total_ref_count++;
+ return 0;
+
+fail:
if (!total_ref_count) {
int i;
@@ -61,21 +72,26 @@
perf_trace_buf[i] = NULL;
}
}
- event->perf_refcount--;
+
+ if (!--tp_event->perf_refcount) {
+ free_percpu(tp_event->perf_events);
+ tp_event->perf_events = NULL;
+ }
return ret;
}
-int perf_trace_enable(int event_id, void *data)
+int perf_trace_init(struct perf_event *p_event)
{
- struct ftrace_event_call *event;
+ struct ftrace_event_call *tp_event;
+ int event_id = p_event->attr.config;
int ret = -EINVAL;
mutex_lock(&event_mutex);
- list_for_each_entry(event, &ftrace_events, list) {
- if (event->id == event_id && event->perf_event_enable &&
- try_module_get(event->mod)) {
- ret = perf_trace_event_enable(event, data);
+ list_for_each_entry(tp_event, &ftrace_events, list) {
+ if (tp_event->id == event_id && tp_event->perf_event_enable &&
+ try_module_get(tp_event->mod)) {
+ ret = perf_trace_event_init(tp_event, p_event);
break;
}
}
@@ -84,53 +100,52 @@
return ret;
}
-static void perf_trace_event_disable(struct ftrace_event_call *event)
+int perf_trace_enable(struct perf_event *p_event)
{
- if (--event->perf_refcount > 0)
- return;
+ struct ftrace_event_call *tp_event = p_event->tp_event;
+ struct hlist_head *list;
- event->perf_event_disable(event);
+ list = tp_event->perf_events;
+ if (WARN_ON_ONCE(!list))
+ return -EINVAL;
- if (!--total_ref_count) {
- char *buf[4];
- int i;
+ list = per_cpu_ptr(list, smp_processor_id());
+ hlist_add_head_rcu(&p_event->hlist_entry, list);
- for (i = 0; i < 4; i++) {
- buf[i] = perf_trace_buf[i];
- rcu_assign_pointer(perf_trace_buf[i], NULL);
- }
-
- /*
- * Ensure every events in profiling have finished before
- * releasing the buffers
- */
- synchronize_sched();
-
- for (i = 0; i < 4; i++)
- free_percpu(buf[i]);
- }
+ return 0;
}
-void perf_trace_disable(int event_id)
+void perf_trace_disable(struct perf_event *p_event)
{
- struct ftrace_event_call *event;
+ hlist_del_rcu(&p_event->hlist_entry);
+}
- mutex_lock(&event_mutex);
- list_for_each_entry(event, &ftrace_events, list) {
- if (event->id == event_id) {
- perf_trace_event_disable(event);
- module_put(event->mod);
- break;
+void perf_trace_destroy(struct perf_event *p_event)
+{
+ struct ftrace_event_call *tp_event = p_event->tp_event;
+ int i;
+
+ if (--tp_event->perf_refcount > 0)
+ return;
+
+ tp_event->perf_event_disable(tp_event);
+
+ free_percpu(tp_event->perf_events);
+ tp_event->perf_events = NULL;
+
+ if (!--total_ref_count) {
+ for (i = 0; i < 4; i++) {
+ free_percpu(perf_trace_buf[i]);
+ perf_trace_buf[i] = NULL;
}
}
- mutex_unlock(&event_mutex);
}
__kprobes void *perf_trace_buf_prepare(int size, unsigned short type,
struct pt_regs *regs, int *rctxp)
{
struct trace_entry *entry;
- char *trace_buf, *raw_data;
+ char *raw_data;
int pc;
BUILD_BUG_ON(PERF_MAX_TRACE_SIZE % sizeof(unsigned long));
@@ -139,13 +154,9 @@
*rctxp = perf_swevent_get_recursion_context();
if (*rctxp < 0)
- goto err_recursion;
+ return NULL;
- trace_buf = rcu_dereference_sched(perf_trace_buf[*rctxp]);
- if (!trace_buf)
- goto err;
-
- raw_data = per_cpu_ptr(trace_buf, smp_processor_id());
+ raw_data = per_cpu_ptr(perf_trace_buf[*rctxp], smp_processor_id());
/* zero the dead bytes from align to not leak stack to user */
memset(&raw_data[size - sizeof(u64)], 0, sizeof(u64));
@@ -155,9 +166,5 @@
entry->type = type;
return raw_data;
-err:
- perf_swevent_put_recursion_context(*rctxp);
-err_recursion:
- return NULL;
}
EXPORT_SYMBOL_GPL(perf_trace_buf_prepare);