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Commit b7e2ecef authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

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



Improves performance.

Acked-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: default avatarPeter 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: default avatarIngo Molnar <mingo@elte.hu>
parent 1c34bde1

include/linux/ftrace_event.h

+3 −6
Original line number Diff line number Diff line
@@ -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

include/trace/ftrace.h

+7 −10
Original line number Diff line number Diff line
@@ -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

kernel/trace/trace_event_perf.c

+29 −44
Original line number Diff line number Diff line
@@ -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;



		for (i = 0; i < 4; i++) {

			buf = (char *)alloc_percpu(perf_trace_t);

			if (!buf)

			goto fail_buf_nmi;

				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);

kernel/trace/trace_kprobe.c

+4 −6
Original line number Diff line number Diff line
@@ -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)

kernel/trace/trace_syscalls.c

+4 −6
Original line number Diff line number Diff line
@@ -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);

}