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

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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>
This commit is contained in:
Peter Zijlstra 2010-05-19 10:52:27 +02:00 • committed by Ingo Molnar
parent 1c34bde13a
commit b7e2ecef92
5 changed files with 48 additions and 73 deletions
Download patch file Download diff file Expand all files Collapse all files

75
kernel/trace/trace_event_perf.c
View file

@ -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;
char *buf;
int i;
rcu_assign_pointer(perf_trace_buf, buf);
for (i = 0; i < 4; i++) {
buf = (char *)alloc_percpu(perf_trace_t);
if (!buf)
goto fail_buf;
buf = (char *)alloc_percpu(perf_trace_t);
if (!buf)
goto fail_buf_nmi;
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:
if (!total_ref_count) {
free_percpu(perf_trace_buf_nmi);
free_percpu(perf_trace_buf);
perf_trace_buf_nmi = NULL;
perf_trace_buf = NULL;
}
fail_buf:
if (!total_ref_count) {
int i;
for (i = 0; i < 4; i++) {
free_percpu(perf_trace_buf[i]);
perf_trace_buf[i] = NULL;
}
}
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);