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perf, trace: Optimize tracepoints by using per-tracepoint-per-cpu hlist to track events

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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>
This commit is contained in:
Peter Zijlstra
2010-05-19 14:02:22 +02:00
committed by Ingo Molnar
parent b7e2ecef92
commit 1c024eca51
7 changed files with 148 additions and 129 deletions
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129
kernel/trace/trace_event_perf.c
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@@ -23,14 +23,25 @@ typedef typeof(unsigned long [PERF_MAX_TRACE_SIZE / sizeof(unsigned long)])
/* 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 @@ static int perf_trace_event_enable(struct ftrace_event_call *event, void *data)
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 @@ fail_buf:
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 @@ int perf_trace_enable(int event_id, void *data)
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 @@ __kprobes void *perf_trace_buf_prepare(int size, unsigned short type,
*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 @@ __kprobes void *perf_trace_buf_prepare(int size, unsigned short type,
entry->type = type;
return raw_data;
err:
perf_swevent_put_recursion_context(*rctxp);
err_recursion:
return NULL;
}
EXPORT_SYMBOL_GPL(perf_trace_buf_prepare);