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tracing/function-graph-tracer: use the more lightweight local clock 

Impact: decrease hangs risks with the graph tracer on slow systems

Since the function graph tracer can spend too much time on timer
interrupts, it's better now to use the more lightweight local
clock. Anyway, the function graph traces are more reliable on a
per cpu trace.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <49af243d.06e9300a.53ad.ffff840c@mx.google.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Frederic Weisbecker 2009-03-05 01:49:22 +01:00 committed by Ingo Molnar
parent c4ef144a9d
commit 0012693ad4
3 changed files with 9 additions and 8 deletions
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2
arch/x86/kernel/ftrace.c
View File

@ -436,7 +436,7 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr)
return;
}
calltime = cpu_clock(raw_smp_processor_id());
calltime = trace_clock_local();
if (ftrace_push_return_trace(old, calltime,
self_addr, &trace.depth) == -EBUSY) {

13
include/linux/ftrace.h
View File

@ -1,15 +1,16 @@
#ifndef _LINUX_FTRACE_H
#define _LINUX_FTRACE_H
#include <linux/linkage.h>
#include <linux/fs.h>
#include <linux/ktime.h>
#include <linux/init.h>
#include <linux/types.h>
#include <linux/module.h>
#include <linux/trace_clock.h>
#include <linux/kallsyms.h>
#include <linux/linkage.h>
#include <linux/bitops.h>
#include <linux/module.h>
#include <linux/ktime.h>
#include <linux/sched.h>
#include <linux/types.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <asm/ftrace.h>

2
kernel/trace/trace_functions_graph.c
View File

@ -112,7 +112,7 @@ unsigned long ftrace_return_to_handler(void)
unsigned long ret;
ftrace_pop_return_trace(&trace, &ret);
trace.rettime = cpu_clock(raw_smp_processor_id());
trace.rettime = trace_clock_local();
ftrace_graph_return(&trace);
if (unlikely(!ret)) {