[tip:perf/core] perf, trace: Optimize tracepoints by removing IRQ-disable from perf/tracepoint interaction

tip-bot for Peter Zijlstra
2010-05-21T11:28:31Z

Commit-ID: b7e2ecef92d2e7785e6d76b41e5ba8bcbc45259d
Gitweb: http://git.kernel.org/tip/b7e2ecef92d2e7785e6d76b41e5ba8bcbc45259d
Author: Peter Zijlstra <a.p.zijlstra@chello.nl>
AuthorDate: Wed, 19 May 2010 10:52:27 +0200
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Fri, 21 May 2010 11:37:56 +0200

perf, trace: Optimize tracepoints by removing IRQ-disable from perf/tracepoint interaction

Improves performance.

Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
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: <1274259525.5605.10352.camel@twins>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
include/linux/ftrace_event.h | 9 ++---
include/trace/ftrace.h | 17 ++++-----
kernel/trace/trace_event_perf.c | 73 +++++++++++++++-----------------------
kernel/trace/trace_kprobe.c | 10 ++---
kernel/trace/trace_syscalls.c | 10 ++---
5 files changed, 47 insertions(+), 72 deletions(-)

diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h
index a9775dd..126071b 100644
--- a/include/linux/ftrace_event.h
+++ b/include/linux/ftrace_event.h
@@ -197,20 +197,17 @@ extern void perf_trace_disable(int event_id);
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, int *rctxp,
- unsigned long *irq_flags);
+extern void *perf_trace_buf_prepare(int size, unsigned short type,
+ struct pt_regs *regs, int *rctxp);

static inline void
perf_trace_buf_submit(void *raw_data, int size, int rctx, u64 addr,
- u64 count, unsigned long irq_flags, struct pt_regs *regs,
- void *event)
+ u64 count, struct pt_regs *regs, void *event)
{
struct trace_entry *entry = raw_data;

perf_tp_event(entry->type, addr, count, raw_data, size, regs, event);
perf_swevent_put_recursion_context(rctx);
- local_irq_restore(irq_flags);
}
#endif

diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h
index 1016b21..f282885 100644
--- a/include/trace/ftrace.h
+++ b/include/trace/ftrace.h
@@ -768,7 +768,6 @@ perf_trace_templ_##call(struct ftrace_event_call *event_call, \
struct ftrace_data_offsets_##call __maybe_unused __data_offsets;\
struct ftrace_raw_##call *entry; \
u64 __addr = 0, __count = 1; \
- unsigned long irq_flags; \
int __entry_size; \
int __data_size; \
int rctx; \
@@ -781,17 +780,18 @@ perf_trace_templ_##call(struct ftrace_event_call *event_call, \
if (WARN_ONCE(__entry_size > PERF_MAX_TRACE_SIZE, \
"profile buffer not large enough")) \
return; \
+ \
entry = (struct ftrace_raw_##call *)perf_trace_buf_prepare( \
- __entry_size, event_call->id, &rctx, &irq_flags); \
+ __entry_size, event_call->id, __regs, &rctx); \
if (!entry) \
return; \
+ \
tstruct \
\
{ assign; } \
\
perf_trace_buf_submit(entry, __entry_size, rctx, __addr, \
- __count, irq_flags, __regs, \
- event_call->perf_data); \
+ __count, __regs, event_call->perf_data); \
}

#undef DEFINE_EVENT
@@ -799,13 +799,10 @@ perf_trace_templ_##call(struct ftrace_event_call *event_call, \
static notrace void perf_trace_##call(proto) \
{ \
struct ftrace_event_call *event_call = &event_##call; \
- struct pt_regs *__regs = &get_cpu_var(perf_trace_regs); \
- \
- perf_fetch_caller_regs(__regs, 1); \
- \
- perf_trace_templ_##template(event_call, __regs, args); \
+ struct pt_regs __regs; \
\
- put_cpu_var(perf_trace_regs); \
+ perf_fetch_caller_regs(&__regs, 1); \
+ perf_trace_templ_##template(event_call, &__regs, args); \
}

#undef DEFINE_EVENT_PRINT
diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c
index 89b780a..a1304f8 100644
--- a/kernel/trace/trace_event_perf.c
+++ b/kernel/trace/trace_event_perf.c
@@ -9,13 +9,9 @@
#include <linux/kprobes.h>
#include "trace.h"

-DEFINE_PER_CPU(struct pt_regs, perf_trace_regs);
-EXPORT_PER_CPU_SYMBOL_GPL(perf_trace_regs);
-
EXPORT_SYMBOL_GPL(perf_arch_fetch_caller_regs);

-static char *perf_trace_buf;
-static char *perf_trace_buf_nmi;
+static char *perf_trace_buf[4];

/*
* Force it to be aligned to unsigned long to avoid misaligned accesses
@@ -29,7 +25,6 @@ static int total_ref_count;

static int perf_trace_event_enable(struct ftrace_event_call *event, void *data)
{
- char *buf;
int ret = -ENOMEM;

if (event->perf_refcount++ > 0) {
@@ -38,17 +33,16 @@ static int perf_trace_event_enable(struct ftrace_event_call *event, void *data)
}

if (!total_ref_count) {
- buf = (char *)alloc_percpu(perf_trace_t);
- if (!buf)
- goto fail_buf;
-
- rcu_assign_pointer(perf_trace_buf, buf);
+ char *buf;
+ int i;

- buf = (char *)alloc_percpu(perf_trace_t);
- if (!buf)
- goto fail_buf_nmi;
+ for (i = 0; i < 4; i++) {
+ buf = (char *)alloc_percpu(perf_trace_t);
+ if (!buf)
+ goto fail_buf;

- rcu_assign_pointer(perf_trace_buf_nmi, buf);
+ rcu_assign_pointer(perf_trace_buf[i], buf);
+ }
}

ret = event->perf_event_enable(event);
@@ -58,14 +52,15 @@ static int perf_trace_event_enable(struct ftrace_event_call *event, void *data)
return 0;
}

-fail_buf_nmi:
+fail_buf:
if (!total_ref_count) {
- free_percpu(perf_trace_buf_nmi);
- free_percpu(perf_trace_buf);
- perf_trace_buf_nmi = NULL;
- perf_trace_buf = NULL;
+ int i;
+
+ for (i = 0; i < 4; i++) {
+ free_percpu(perf_trace_buf[i]);
+ perf_trace_buf[i] = NULL;
+ }
}
-fail_buf:
event->perf_refcount--;

return ret;
@@ -91,19 +86,19 @@ int perf_trace_enable(int event_id, void *data)

static void perf_trace_event_disable(struct ftrace_event_call *event)
{
- char *buf, *nmi_buf;
-
if (--event->perf_refcount > 0)
return;

event->perf_event_disable(event);

if (!--total_ref_count) {
- buf = perf_trace_buf;
- rcu_assign_pointer(perf_trace_buf, NULL);
+ char *buf[4];
+ int i;

- nmi_buf = perf_trace_buf_nmi;
- rcu_assign_pointer(perf_trace_buf_nmi, NULL);
+ 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
@@ -111,8 +106,8 @@ static void perf_trace_event_disable(struct ftrace_event_call *event)
*/
synchronize_sched();

- free_percpu(buf);
- free_percpu(nmi_buf);
+ for (i = 0; i < 4; i++)
+ free_percpu(buf[i]);
}
}

@@ -132,47 +127,37 @@ void perf_trace_disable(int event_id)
}

__kprobes void *perf_trace_buf_prepare(int size, unsigned short type,
- int *rctxp, unsigned long *irq_flags)
+ struct pt_regs *regs, int *rctxp)
{
struct trace_entry *entry;
char *trace_buf, *raw_data;
- int pc, cpu;
+ int pc;

BUILD_BUG_ON(PERF_MAX_TRACE_SIZE % sizeof(unsigned long));

pc = preempt_count();

- /* Protect the per cpu buffer, begin the rcu read side */
- local_irq_save(*irq_flags);
-
*rctxp = perf_swevent_get_recursion_context();
if (*rctxp < 0)
goto err_recursion;

- cpu = smp_processor_id();
-
- if (in_nmi())
- trace_buf = rcu_dereference_sched(perf_trace_buf_nmi);
- else
- trace_buf = rcu_dereference_sched(perf_trace_buf);
-
+ trace_buf = rcu_dereference_sched(perf_trace_buf[*rctxp]);
if (!trace_buf)
goto err;

- raw_data = per_cpu_ptr(trace_buf, cpu);
+ raw_data = per_cpu_ptr(trace_buf, smp_processor_id());

/* zero the dead bytes from align to not leak stack to user */
memset(&raw_data[size - sizeof(u64)], 0, sizeof(u64));

entry = (struct trace_entry *)raw_data;
- tracing_generic_entry_update(entry, *irq_flags, pc);
+ tracing_generic_entry_update(entry, regs->flags, pc);
entry->type = type;

return raw_data;
err:
perf_swevent_put_recursion_context(*rctxp);
err_recursion:
- local_irq_restore(*irq_flags);
return NULL;
}
EXPORT_SYMBOL_GPL(perf_trace_buf_prepare);
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 2d7bf41..20c96de 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -1343,7 +1343,6 @@ static __kprobes void kprobe_perf_func(struct kprobe *kp,
struct kprobe_trace_entry_head *entry;
u8 *data;
int size, __size, i;
- unsigned long irq_flags;
int rctx;

__size = sizeof(*entry) + tp->size;
@@ -1353,7 +1352,7 @@ static __kprobes void kprobe_perf_func(struct kprobe *kp,
"profile buffer not large enough"))
return;

- entry = perf_trace_buf_prepare(size, call->id, &rctx, &irq_flags);
+ entry = perf_trace_buf_prepare(size, call->id, regs, &rctx);
if (!entry)
return;

@@ -1362,7 +1361,7 @@ 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, irq_flags, regs, call->perf_data);
+ perf_trace_buf_submit(entry, size, rctx, entry->ip, 1, regs, call->perf_data);
}

/* Kretprobe profile handler */
@@ -1374,7 +1373,6 @@ static __kprobes void kretprobe_perf_func(struct kretprobe_instance *ri,
struct kretprobe_trace_entry_head *entry;
u8 *data;
int size, __size, i;
- unsigned long irq_flags;
int rctx;

__size = sizeof(*entry) + tp->size;
@@ -1384,7 +1382,7 @@ static __kprobes void kretprobe_perf_func(struct kretprobe_instance *ri,
"profile buffer not large enough"))
return;

- entry = perf_trace_buf_prepare(size, call->id, &rctx, &irq_flags);
+ entry = perf_trace_buf_prepare(size, call->id, regs, &rctx);
if (!entry)
return;

@@ -1395,7 +1393,7 @@ static __kprobes void kretprobe_perf_func(struct kretprobe_instance *ri,
call_fetch(&tp->args[i].fetch, regs, data + tp->args[i].offset);

perf_trace_buf_submit(entry, size, rctx, entry->ret_ip, 1,
- irq_flags, regs, call->perf_data);
+ regs, call->perf_data);
}

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 9eff1a4..a657cef 100644
--- a/kernel/trace/trace_syscalls.c
+++ b/kernel/trace/trace_syscalls.c
@@ -438,7 +438,6 @@ static void perf_syscall_enter(struct pt_regs *regs, long id)
{
struct syscall_metadata *sys_data;
struct syscall_trace_enter *rec;
- unsigned long flags;
int syscall_nr;
int rctx;
int size;
@@ -461,14 +460,14 @@ static void perf_syscall_enter(struct pt_regs *regs, long id)
return;

rec = (struct syscall_trace_enter *)perf_trace_buf_prepare(size,
- sys_data->enter_event->id, &rctx, &flags);
+ sys_data->enter_event->id, regs, &rctx);
if (!rec)
return;

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, flags, regs,
+ perf_trace_buf_submit(rec, size, rctx, 0, 1, regs,
sys_data->enter_event->perf_data);
}

@@ -511,7 +510,6 @@ static void perf_syscall_exit(struct pt_regs *regs, long ret)
{
struct syscall_metadata *sys_data;
struct syscall_trace_exit *rec;
- unsigned long flags;
int syscall_nr;
int rctx;
int size;
@@ -537,14 +535,14 @@ static void perf_syscall_exit(struct pt_regs *regs, long ret)
return;

rec = (struct syscall_trace_exit *)perf_trace_buf_prepare(size,
- sys_data->exit_event->id, &rctx, &flags);
+ sys_data->exit_event->id, regs, &rctx);
if (!rec)
return;

rec->nr = syscall_nr;
rec->ret = syscall_get_return_value(current, regs);

- perf_trace_buf_submit(rec, size, rctx, 0, 1, flags, regs,
+ perf_trace_buf_submit(rec, size, rctx, 0, 1, regs,
sys_data->exit_event->perf_data);
}