[PATCH 02/10] perf, trace: Use per-tracepoint-per-cpu hlist to track events

Peter Zijlstra
2010-05-21T09:13:29Z

[-- Attachment #1: perf-trace-per-cpu-fold.patch --]
[-- Type: text/plain, Size: 17665 bytes --]

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>
---
include/linux/ftrace_event.h | 16 ++---
include/linux/perf_event.h | 6 +
include/trace/ftrace.h | 4 -
kernel/perf_event.c | 94 +++++++++++++++--------------
kernel/trace/trace_event_perf.c | 127 +++++++++++++++++++++-------------------
kernel/trace/trace_kprobe.c | 9 +-
kernel/trace/trace_syscalls.c | 11 ++-
7 files changed, 143 insertions(+), 124 deletions(-)

Index: linux-2.6/include/linux/ftrace_event.h
===================================================================
--- linux-2.6.orig/include/linux/ftrace_event.h
+++ linux-2.6/include/linux/ftrace_event.h
@@ -133,7 +133,7 @@ struct ftrace_event_call {
void *data;

int perf_refcount;
- void *perf_data;
+ struct hlist_head *perf_events;
int (*perf_event_enable)(struct ftrace_event_call *);
void (*perf_event_disable)(struct ftrace_event_call *);
};
@@ -192,9 +192,11 @@ struct perf_event;

DECLARE_PER_CPU(struct pt_regs, perf_trace_regs);

-extern int perf_trace_enable(int event_id, void *data);
-extern void perf_trace_disable(int event_id);
-extern int ftrace_profile_set_filter(struct perf_event *event, int event_id,
+extern int perf_trace_init(struct perf_event *event);
+extern void perf_trace_destroy(struct perf_event *event);
+extern int perf_trace_enable(struct perf_event *event);
+extern void perf_trace_disable(struct perf_event *event);
+extern int ftrace_profile_set_filter(struct perf_event *event, int event_id,
char *filter_str);
extern void ftrace_profile_free_filter(struct perf_event *event);
extern void *perf_trace_buf_prepare(int size, unsigned short type,
@@ -202,11 +204,9 @@ extern void *perf_trace_buf_prepare(int

static inline void
perf_trace_buf_submit(void *raw_data, int size, int rctx, u64 addr,
- u64 count, struct pt_regs *regs, void *event)
+ u64 count, struct pt_regs *regs, void *head)
{
- struct trace_entry *entry = raw_data;
-
- perf_tp_event(entry->type, addr, count, raw_data, size, regs, event);
+ perf_tp_event(addr, count, raw_data, size, regs, head);
perf_swevent_put_recursion_context(rctx);
}
#endif
Index: linux-2.6/include/trace/ftrace.h
===================================================================
--- linux-2.6.orig/include/trace/ftrace.h
+++ linux-2.6/include/trace/ftrace.h
@@ -768,6 +768,7 @@ perf_trace_templ_##call(struct ftrace_ev
struct ftrace_data_offsets_##call __maybe_unused __data_offsets;\
struct ftrace_raw_##call *entry; \
u64 __addr = 0, __count = 1; \
+ struct hlist_head *head; \
int __entry_size; \
int __data_size; \
int rctx; \
@@ -790,8 +791,9 @@ perf_trace_templ_##call(struct ftrace_ev
\
{ assign; } \
\
+ head = per_cpu_ptr(event_call->perf_events, smp_processor_id());\
perf_trace_buf_submit(entry, __entry_size, rctx, __addr, \
- __count, __regs, event_call->perf_data); \
+ __count, __regs, head); \
}

#undef DEFINE_EVENT
Index: linux-2.6/kernel/trace/trace_event_perf.c
===================================================================
--- linux-2.6.orig/kernel/trace/trace_event_perf.c
+++ linux-2.6/kernel/trace/trace_event_perf.c
@@ -23,14 +23,25 @@ typedef typeof(unsigned long [PERF_MAX_T
/* 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(struc
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
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(i

*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(i
entry->type = type;

return raw_data;
-err:
- perf_swevent_put_recursion_context(*rctxp);
-err_recursion:
- return NULL;
}
EXPORT_SYMBOL_GPL(perf_trace_buf_prepare);
Index: linux-2.6/kernel/trace/trace_kprobe.c
===================================================================
--- linux-2.6.orig/kernel/trace/trace_kprobe.c
+++ linux-2.6/kernel/trace/trace_kprobe.c
@@ -1341,6 +1341,7 @@ static __kprobes void kprobe_perf_func(s
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(s
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_fun
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_fun
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)
Index: linux-2.6/kernel/trace/trace_syscalls.c
===================================================================
--- linux-2.6.orig/kernel/trace/trace_syscalls.c
+++ linux-2.6/kernel/trace/trace_syscalls.c
@@ -438,6 +438,7 @@ static void perf_syscall_enter(struct pt
{
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
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_
{
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_
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)
Index: linux-2.6/kernel/perf_event.c
===================================================================
--- linux-2.6.orig/kernel/perf_event.c
+++ linux-2.6/kernel/perf_event.c
@@ -4004,9 +4004,6 @@ static void perf_swevent_add(struct perf
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)
{
@@ -4036,10 +4033,6 @@ static int perf_swevent_match(struct per
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;
}

@@ -4094,7 +4087,7 @@ 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())
@@ -4106,10 +4099,8 @@ int perf_swevent_get_recursion_context(v
else
rctx = 0;

- if (cpuctx->recursion[rctx]) {
- put_cpu_var(perf_cpu_context);
+ if (cpuctx->recursion[rctx])
return -1;
- }

cpuctx->recursion[rctx]++;
barrier();
@@ -4123,7 +4114,6 @@ void perf_swevent_put_recursion_context(
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);

@@ -4134,6 +4124,7 @@ void __perf_sw_event(u32 event_id, u64 n
struct perf_sample_data data;
int rctx;

+ preempt_disable_notrace();
rctx = perf_swevent_get_recursion_context();
if (rctx < 0)
return;
@@ -4143,6 +4134,7 @@ void __perf_sw_event(u32 event_id, u64 n
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)
@@ -4451,11 +4443,43 @@ static int swevent_hlist_get(struct perf

#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,
@@ -4464,30 +4488,18 @@ void perf_tp_event(int event_id, u64 add
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)
@@ -4503,17 +4515,13 @@ static const struct pmu *tp_perf_event_i
!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)
@@ -4541,12 +4549,6 @@ static void perf_event_free_filter(struc

#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;
Index: linux-2.6/include/linux/perf_event.h
===================================================================
--- linux-2.6.orig/include/linux/perf_event.h
+++ linux-2.6/include/linux/perf_event.h
@@ -727,6 +727,7 @@ struct perf_event {
perf_overflow_handler_t overflow_handler;

#ifdef CONFIG_EVENT_TRACING
+ struct ftrace_event_call *tp_event;
struct event_filter *filter;
#endif

@@ -992,8 +993,9 @@ static inline bool perf_paranoid_kernel(
}

extern void perf_event_init(void);
-extern void perf_tp_event(int event_id, u64 addr, u64 count, void *record,
- int entry_size, struct pt_regs *regs, void *event);
+extern void perf_tp_event(u64 addr, u64 count, void *record,
+ int entry_size, struct pt_regs *regs,
+ struct hlist_head *head);
extern void perf_bp_event(struct perf_event *event, void *data);

#ifndef perf_misc_flags