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>

4 files changed, 128 insertions, 113 deletions

diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 45b7aec55458..3f2cc313ee25 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -4005,9 +4005,6 @@ static void perf_swevent_add(struct perf_event *event, u64 nr,
         perf_swevent_overflow(event, 0, nmi, data, regs);
 }
 
-static int perf_tp_event_match(struct perf_event *event,
-                                struct perf_sample_data *data);
-
 static int perf_exclude_event(struct perf_event *event,
                               struct pt_regs *regs)
 {
@@ -4037,10 +4034,6 @@ static int perf_swevent_match(struct perf_event *event,
         if (perf_exclude_event(event, regs))
                 return 0;
 
-        if (event->attr.type == PERF_TYPE_TRACEPOINT &&
-            !perf_tp_event_match(event, data))
-                return 0;
-
         return 1;
 }
 
@@ -4122,7 +4115,7 @@ end:
 
 int perf_swevent_get_recursion_context(void)
 {
-        struct perf_cpu_context *cpuctx = &get_cpu_var(perf_cpu_context);
+        struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
         int rctx;
 
         if (in_nmi())
@@ -4134,10 +4127,8 @@ int perf_swevent_get_recursion_context(void)
         else
                 rctx = 0;
 
-        if (cpuctx->recursion[rctx]) {
-                put_cpu_var(perf_cpu_context);
+        if (cpuctx->recursion[rctx])
                 return -1;
-        }
 
         cpuctx->recursion[rctx]++;
         barrier();
@@ -4151,7 +4142,6 @@ void perf_swevent_put_recursion_context(int rctx)
         struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
         barrier();
         cpuctx->recursion[rctx]--;
-        put_cpu_var(perf_cpu_context);
 }
 EXPORT_SYMBOL_GPL(perf_swevent_put_recursion_context);
 
@@ -4162,6 +4152,7 @@ void __perf_sw_event(u32 event_id, u64 nr, int nmi,
         struct perf_sample_data data;
         int rctx;
 
+        preempt_disable_notrace();
         rctx = perf_swevent_get_recursion_context();
         if (rctx < 0)
                 return;
@@ -4171,6 +4162,7 @@ void __perf_sw_event(u32 event_id, u64 nr, int nmi,
         do_perf_sw_event(PERF_TYPE_SOFTWARE, event_id, nr, nmi, &data, regs);
 
         perf_swevent_put_recursion_context(rctx);
+        preempt_enable_notrace();
 }
 
 static void perf_swevent_read(struct perf_event *event)
@@ -4486,11 +4478,43 @@ static int swevent_hlist_get(struct perf_event *event)
 
 #ifdef CONFIG_EVENT_TRACING
 
-void perf_tp_event(int event_id, u64 addr, u64 count, void *record,
-                   int entry_size, struct pt_regs *regs, void *event)
+static const struct pmu perf_ops_tracepoint = {
+        .enable         = perf_trace_enable,
+        .disable        = perf_trace_disable,
+        .read           = perf_swevent_read,
+        .unthrottle     = perf_swevent_unthrottle,
+};
+
+static int perf_tp_filter_match(struct perf_event *event,
+                                struct perf_sample_data *data)
+{
+        void *record = data->raw->data;
+
+        if (likely(!event->filter) || filter_match_preds(event->filter, record))
+                return 1;
+        return 0;
+}
+
+static int perf_tp_event_match(struct perf_event *event,
+                                struct perf_sample_data *data,
+                                struct pt_regs *regs)
+{
+        if (perf_exclude_event(event, regs))
+                return 0;
+
+        if (!perf_tp_filter_match(event, data))
+                return 0;
+
+        return 1;
+}
+
+void perf_tp_event(u64 addr, u64 count, void *record, int entry_size,
+                   struct pt_regs *regs, struct hlist_head *head)
 {
-        const int type = PERF_TYPE_TRACEPOINT;
         struct perf_sample_data data;
+        struct perf_event *event;
+        struct hlist_node *node;
+
         struct perf_raw_record raw = {
                 .size = entry_size,
                 .data = record,
@@ -4499,30 +4523,18 @@ void perf_tp_event(int event_id, u64 addr, u64 count, void *record,
         perf_sample_data_init(&data, addr);
         data.raw = &raw;
 
-        if (!event) {
-                do_perf_sw_event(type, event_id, count, 1, &data, regs);
-                return;
+        rcu_read_lock();
+        hlist_for_each_entry_rcu(event, node, head, hlist_entry) {
+                if (perf_tp_event_match(event, &data, regs))
+                        perf_swevent_add(event, count, 1, &data, regs);
         }
-
-        if (perf_swevent_match(event, type, event_id, &data, regs))
-                perf_swevent_add(event, count, 1, &data, regs);
+        rcu_read_unlock();
 }
 EXPORT_SYMBOL_GPL(perf_tp_event);
 
-static int perf_tp_event_match(struct perf_event *event,
-                                struct perf_sample_data *data)
-{
-        void *record = data->raw->data;
-
-        if (likely(!event->filter) || filter_match_preds(event->filter, record))
-                return 1;
-        return 0;
-}
-
 static void tp_perf_event_destroy(struct perf_event *event)
 {
-        perf_trace_disable(event->attr.config);
-        swevent_hlist_put(event);
+        perf_trace_destroy(event);
 }
 
 static const struct pmu *tp_perf_event_init(struct perf_event *event)
@@ -4538,17 +4550,13 @@ static const struct pmu *tp_perf_event_init(struct perf_event *event)
                         !capable(CAP_SYS_ADMIN))
                 return ERR_PTR(-EPERM);
 
-        if (perf_trace_enable(event->attr.config, event))
+        err = perf_trace_init(event);
+        if (err)
                 return NULL;
 
         event->destroy = tp_perf_event_destroy;
-        err = swevent_hlist_get(event);
-        if (err) {
-                perf_trace_disable(event->attr.config);
-                return ERR_PTR(err);
-        }
 
-        return &perf_ops_generic;
+        return &perf_ops_tracepoint;
 }
 
 static int perf_event_set_filter(struct perf_event *event, void __user *arg)
@@ -4576,12 +4584,6 @@ static void perf_event_free_filter(struct perf_event *event)
 
 #else
 
-static int perf_tp_event_match(struct perf_event *event,
-                                struct perf_sample_data *data)
-{
-        return 1;
-}
-
 static const struct pmu *tp_perf_event_init(struct perf_event *event)
 {
         return NULL;
diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c
index a1304f8c4440..39d5ea7b0653 100644
--- a/kernel/trace/trace_event_perf.c
+++ b/kernel/trace/trace_event_perf.c
@@ -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;
-
-                for (i = 0; i < 4; i++) {
-                        buf[i] = perf_trace_buf[i];
-                        rcu_assign_pointer(perf_trace_buf[i], NULL);
-                }
+        list = per_cpu_ptr(list, smp_processor_id());
+        hlist_add_head_rcu(&p_event->hlist_entry, list);
 
-                /*
-                 * Ensure every events in profiling have finished before
-                 * releasing the buffers
-                 */
-                synchronize_sched();
+        return 0;
+}
 
-                for (i = 0; i < 4; i++)
-                        free_percpu(buf[i]);
-        }
+void perf_trace_disable(struct perf_event *p_event)
+{
+        hlist_del_rcu(&p_event->hlist_entry);
 }
 
-void perf_trace_disable(int event_id)
+void perf_trace_destroy(struct perf_event *p_event)
 {
-        struct ftrace_event_call *event;
+        struct ftrace_event_call *tp_event = p_event->tp_event;
+        int i;
 
-        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;
+        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;
-
-        trace_buf = rcu_dereference_sched(perf_trace_buf[*rctxp]);
-        if (!trace_buf)
-                goto err;
+                return NULL;
 
-        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);
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 20c96de0aea0..4681f60dac00 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -1341,6 +1341,7 @@ static __kprobes void kprobe_perf_func(struct kprobe *kp,
         struct trace_probe *tp = container_of(kp, struct trace_probe, rp.kp);
         struct ftrace_event_call *call = &tp->call;
         struct kprobe_trace_entry_head *entry;
+        struct hlist_head *head;
         u8 *data;
         int size, __size, i;
         int rctx;
@@ -1361,7 +1362,8 @@ static __kprobes void kprobe_perf_func(struct kprobe *kp,
         for (i = 0; i < tp->nr_args; i++)
                 call_fetch(&tp->args[i].fetch, regs, data + tp->args[i].offset);
 
-        perf_trace_buf_submit(entry, size, rctx, entry->ip, 1, regs, call->perf_data);
+        head = per_cpu_ptr(call->perf_events, smp_processor_id());
+        perf_trace_buf_submit(entry, size, rctx, entry->ip, 1, regs, head);
 }
 
 /* Kretprobe profile handler */
@@ -1371,6 +1373,7 @@ static __kprobes void kretprobe_perf_func(struct kretprobe_instance *ri,
         struct trace_probe *tp = container_of(ri->rp, struct trace_probe, rp);
         struct ftrace_event_call *call = &tp->call;
         struct kretprobe_trace_entry_head *entry;
+        struct hlist_head *head;
         u8 *data;
         int size, __size, i;
         int rctx;
@@ -1392,8 +1395,8 @@ static __kprobes void kretprobe_perf_func(struct kretprobe_instance *ri,
         for (i = 0; i < tp->nr_args; i++)
                 call_fetch(&tp->args[i].fetch, regs, data + tp->args[i].offset);
 
-        perf_trace_buf_submit(entry, size, rctx, entry->ret_ip, 1,
-                              regs, call->perf_data);
+        head = per_cpu_ptr(call->perf_events, smp_processor_id());
+        perf_trace_buf_submit(entry, size, rctx, entry->ret_ip, 1, regs, head);
 }
 
 static int probe_perf_enable(struct ftrace_event_call *call)
diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
index a657cefbb137..eb769f270291 100644
--- a/kernel/trace/trace_syscalls.c
+++ b/kernel/trace/trace_syscalls.c
@@ -438,6 +438,7 @@ static void perf_syscall_enter(struct pt_regs *regs, long id)
 {
         struct syscall_metadata *sys_data;
         struct syscall_trace_enter *rec;
+        struct hlist_head *head;
         int syscall_nr;
         int rctx;
         int size;
@@ -467,8 +468,9 @@ static void perf_syscall_enter(struct pt_regs *regs, long id)
         rec->nr = syscall_nr;
         syscall_get_arguments(current, regs, 0, sys_data->nb_args,
                                (unsigned long *)&rec->args);
-        perf_trace_buf_submit(rec, size, rctx, 0, 1, regs,
-                        sys_data->enter_event->perf_data);
+
+        head = per_cpu_ptr(sys_data->enter_event->perf_events, smp_processor_id());
+        perf_trace_buf_submit(rec, size, rctx, 0, 1, regs, head);
 }
 
 int perf_sysenter_enable(struct ftrace_event_call *call)
@@ -510,6 +512,7 @@ static void perf_syscall_exit(struct pt_regs *regs, long ret)
 {
         struct syscall_metadata *sys_data;
         struct syscall_trace_exit *rec;
+        struct hlist_head *head;
         int syscall_nr;
         int rctx;
         int size;
@@ -542,8 +545,8 @@ static void perf_syscall_exit(struct pt_regs *regs, long ret)
         rec->nr = syscall_nr;
         rec->ret = syscall_get_return_value(current, regs);
 
-        perf_trace_buf_submit(rec, size, rctx, 0, 1, regs,
-                        sys_data->exit_event->perf_data);
+        head = per_cpu_ptr(sys_data->exit_event->perf_events, smp_processor_id());
+        perf_trace_buf_submit(rec, size, rctx, 0, 1, regs, head);
 }
 
 int perf_sysexit_enable(struct ftrace_event_call *call)