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Date: Fri, 26 Feb 2010 20:32:35 -0500
From: Steven Rostedt <rostedt@...dmis.org>
To: Frederic Weisbecker <fweisbec@...il.com>
Cc: LKML <linux-kernel@...r.kernel.org>,
Tim Bird <tim.bird@...sony.com>, Ingo Molnar <mingo@...e.hu>
Subject: [PATCH][RFC] ftrace: add tracing_thresh support to function_graph
tracer (v3)
Frederic,
Can you take look at this patch, and if you agree, can you give it your
ACK? Applying this on top of my pull request gives a nice output:
[root@...hel51 tracing]# echo 300 > tracing_thresh
[root@...hel51 tracing]# cat trace | head -30
# tracer: function_graph
#
# CPU DURATION FUNCTION CALLS
# | | | | | | |
1) ! 3630.044 us | } (__dentry_open)
1) ! 3632.456 us | } (nameidata_to_filp)
1) ! 3685.980 us | } (do_filp_open)
1) ! 3701.625 us | } (do_sys_open)
1) ! 3702.830 us | } (sys_open)
------------------------------------------
1) bash-4190 => events/-16
------------------------------------------
1) ! 4152.329 us | } (schedule)
------------------------------------------
1) events/-16 => bash-4190
------------------------------------------
1) ! 461.230 us | } (_raw_spin_unlock_irqrestore)
1) ! 466.865 us | } (tty_ldisc_try)
1) ! 468.948 us | } (tty_ldisc_ref_wait)
0) ! 333.541 us | } (walk_tg_tree)
0) ! 339.638 us | } (update_shares)
0) ! 488.176 us | } (rebalance_domains)
0) ! 490.382 us | } (run_rebalance_domains)
0) ! 532.406 us | } (__do_softirq)
0) ! 536.246 us | } (do_softirq)
0) ! 540.842 us | } (irq_exit)
0) ! 593.286 us | } (smp_apic_timer_interrupt)
(note, I forgot to update the changelog, I'll do that next)
-- Steve
commit c020a9a11ec44e0c81f1aa16781d2d42c6c5e560
Author: Tim Bird <tim.bird@...sony.com>
Date: Thu Feb 25 15:36:43 2010 -0800
ftrace: add tracing_thresh support to function_graph tracer (v3)
Add support for tracing_thresh to the function_graph tracer. This
version of this feature isolates the checks into new entry and
return functions, to avoid adding more conditional code into the
main function_graph paths.
Also, add support for specifying tracing_thresh on the kernel
command line. When used like so: "tracing_thresh=200 ftrace=function_graph"
this can be used to analyse system startup. It is important to disable
tracing soon after boot, in order to avoid losing the trace data.
Note: the elimination of 'notrace' in the definition of '__init'
may be controversial. This can be removed, or made conditional,
if it's a bit too scary, but it worked OK for me. Tracing during
kernel startup still works, just with no visibility of routines
declared __init.
Signed-off-by: Tim Bird <tim.bird@...sony.com>
LKML-Reference: <4B87098B.4040308@...sony.com>
Signed-off-by: Steven Rostedt <rostedt@...dmis.org>
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 032c57c..34ead59 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -374,6 +374,21 @@ static int __init set_buf_size(char *str)
}
__setup("trace_buf_size=", set_buf_size);
+static int __init set_tracing_thresh(char *str)
+{
+ unsigned long threshhold;
+ int ret;
+
+ if (!str)
+ return 0;
+ ret = strict_strtoul(str, 0, &threshhold);
+ if (ret < 0)
+ return 0;
+ tracing_thresh = threshhold * 1000;
+ return 1;
+}
+__setup("tracing_thresh=", set_tracing_thresh);
+
unsigned long nsecs_to_usecs(unsigned long nsecs)
{
return nsecs / 1000;
@@ -579,9 +594,10 @@ static ssize_t trace_seq_to_buffer(struct trace_seq *s, void *buf, size_t cnt)
static arch_spinlock_t ftrace_max_lock =
(arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
+unsigned long __read_mostly tracing_thresh;
+
#ifdef CONFIG_TRACER_MAX_TRACE
unsigned long __read_mostly tracing_max_latency;
-unsigned long __read_mostly tracing_thresh;
/*
* Copy the new maximum trace into the separate maximum-trace
@@ -4248,10 +4264,10 @@ static __init int tracer_init_debugfs(void)
#ifdef CONFIG_TRACER_MAX_TRACE
trace_create_file("tracing_max_latency", 0644, d_tracer,
&tracing_max_latency, &tracing_max_lat_fops);
+#endif
trace_create_file("tracing_thresh", 0644, d_tracer,
&tracing_thresh, &tracing_max_lat_fops);
-#endif
trace_create_file("README", 0444, d_tracer,
NULL, &tracing_readme_fops);
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index fd05bca..1bc8cd1 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -396,9 +396,10 @@ extern int process_new_ksym_entry(char *ksymname, int op, unsigned long addr);
extern unsigned long nsecs_to_usecs(unsigned long nsecs);
+extern unsigned long tracing_thresh;
+
#ifdef CONFIG_TRACER_MAX_TRACE
extern unsigned long tracing_max_latency;
-extern unsigned long tracing_thresh;
void update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu);
void update_max_tr_single(struct trace_array *tr,
diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index e998a82..aaf580c 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -237,6 +237,14 @@ int trace_graph_entry(struct ftrace_graph_ent *trace)
return ret;
}
+int trace_graph_thresh_entry(struct ftrace_graph_ent *trace)
+{
+ if (tracing_thresh)
+ return 1;
+ else
+ return trace_graph_entry(trace);
+}
+
static void __trace_graph_return(struct trace_array *tr,
struct ftrace_graph_ret *trace,
unsigned long flags,
@@ -290,13 +298,26 @@ void set_graph_array(struct trace_array *tr)
smp_mb();
}
+void trace_graph_thresh_return(struct ftrace_graph_ret *trace)
+{
+ if (tracing_thresh &&
+ (trace->rettime - trace->calltime < tracing_thresh))
+ return;
+ else
+ trace_graph_return(trace);
+}
+
static int graph_trace_init(struct trace_array *tr)
{
int ret;
set_graph_array(tr);
- ret = register_ftrace_graph(&trace_graph_return,
- &trace_graph_entry);
+ if (tracing_thresh)
+ ret = register_ftrace_graph(&trace_graph_thresh_return,
+ &trace_graph_thresh_entry);
+ else
+ ret = register_ftrace_graph(&trace_graph_return,
+ &trace_graph_entry);
if (ret)
return ret;
tracing_start_cmdline_record();
--
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