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Date: Wed, 19 May 2010 10:58:45 +0200
From: Peter Zijlstra <peterz@...radead.org>
To: Frederic Weisbecker <fweisbec@...il.com>
Cc: mingo@...hat.com, hpa@...or.com, paulus@...ba.org, acme@...hat.com,
linux-kernel@...r.kernel.org, efault@....de, rostedt@...dmis.org,
tglx@...utronix.de, mingo@...e.hu,
linux-tip-commits@...r.kernel.org
Subject: Re: [tip:perf/core] perf/ftrace: Optimize perf/tracepoint
interaction for single events
How about something like the below?
---
Subject: perf, trace: Remove IRQ-disable from perf/tracepoint interaction
From: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Date: Wed May 19 10:52:27 CEST 2010
Signed-off-by: Peter Zijlstra <a.p.zijlstra@...llo.nl>
---
include/linux/ftrace_event.h | 9 +----
include/trace/ftrace.h | 17 ++++------
kernel/trace/trace_event_perf.c | 67 ++++++++++++++++------------------------
kernel/trace/trace_kprobe.c | 10 ++---
kernel/trace/trace_syscalls.c | 10 ++---
5 files changed, 46 insertions(+), 67 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
@@ -197,20 +197,17 @@ extern void perf_trace_disable(int 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, 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
Index: linux-2.6/include/trace/ftrace.h
===================================================================
--- linux-2.6.orig/include/trace/ftrace.h
+++ linux-2.6/include/trace/ftrace.h
@@ -768,7 +768,6 @@ 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; \
- unsigned long irq_flags; \
int __entry_size; \
int __data_size; \
int rctx; \
@@ -781,17 +780,18 @@ perf_trace_templ_##call(struct ftrace_ev
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_ev
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
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
@@ -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
@@ -38,17 +34,16 @@ static int perf_trace_event_enable(struc
}
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);
@@ -60,10 +55,12 @@ static int perf_trace_event_enable(struc
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;
+ int i;
+
+ for (i = 0; i < 4; i++) {
+ free_percpu(perf_trace_buf[i]);
+ perf_trace_buf[i] = NULL;
+ }
}
fail_buf:
event->perf_refcount--;
@@ -99,11 +96,13 @@ static void perf_trace_event_disable(str
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 +110,8 @@ static void perf_trace_event_disable(str
*/
synchronize_sched();
- free_percpu(buf);
- free_percpu(nmi_buf);
+ for (i = 0; i < 4; i++)
+ free_percpu(buf[i]);
}
}
@@ -132,47 +131,37 @@ 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);
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
@@ -1343,7 +1343,6 @@ static __kprobes void kprobe_perf_func(s
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(s
"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(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, 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_fun
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_fun
"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_fun
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)
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
@@ -438,7 +438,6 @@ static void perf_syscall_enter(struct pt
{
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
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_
{
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_
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);
}
--
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