function-graph: Add tracing_thresh support to function_graph tracer
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. When the tracing_thresh is set and the function graph tracer is enabled, only the functions that took longer than the time in microseconds that was set in tracing_thresh are recorded. To do this efficiently, only the function exits are recorded: [tracing]# echo 100 > tracing_thresh [tracing]# echo function_graph > current_tracer [tracing]# cat trace # tracer: function_graph # # CPU DURATION FUNCTION CALLS # | | | | | | | 1) ! 119.214 us | } /* smp_apic_timer_interrupt */ 1) <========== | 0) ! 101.527 us | } /* __rcu_process_callbacks */ 0) ! 126.461 us | } /* rcu_process_callbacks */ 0) ! 145.111 us | } /* __do_softirq */ 0) ! 149.667 us | } /* do_softirq */ 0) ! 168.817 us | } /* irq_exit */ 0) ! 248.254 us | } /* smp_apic_timer_interrupt */ 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. Acked-by: Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by: Tim Bird <tim.bird@am.sony.com> LKML-Reference: <4B87098B.4040308@am.sony.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
parent
1acaa1b2d9
commit
0e95017355
3 changed files with 43 additions and 5 deletions
|
@ -374,6 +374,21 @@ static int __init set_buf_size(char *str)
|
||||||
}
|
}
|
||||||
__setup("trace_buf_size=", set_buf_size);
|
__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)
|
unsigned long nsecs_to_usecs(unsigned long nsecs)
|
||||||
{
|
{
|
||||||
return nsecs / 1000;
|
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 =
|
static arch_spinlock_t ftrace_max_lock =
|
||||||
(arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
|
(arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
|
||||||
|
|
||||||
|
unsigned long __read_mostly tracing_thresh;
|
||||||
|
|
||||||
#ifdef CONFIG_TRACER_MAX_TRACE
|
#ifdef CONFIG_TRACER_MAX_TRACE
|
||||||
unsigned long __read_mostly tracing_max_latency;
|
unsigned long __read_mostly tracing_max_latency;
|
||||||
unsigned long __read_mostly tracing_thresh;
|
|
||||||
|
|
||||||
/*
|
/*
|
||||||
* Copy the new maximum trace into the separate maximum-trace
|
* 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
|
#ifdef CONFIG_TRACER_MAX_TRACE
|
||||||
trace_create_file("tracing_max_latency", 0644, d_tracer,
|
trace_create_file("tracing_max_latency", 0644, d_tracer,
|
||||||
&tracing_max_latency, &tracing_max_lat_fops);
|
&tracing_max_latency, &tracing_max_lat_fops);
|
||||||
|
#endif
|
||||||
|
|
||||||
trace_create_file("tracing_thresh", 0644, d_tracer,
|
trace_create_file("tracing_thresh", 0644, d_tracer,
|
||||||
&tracing_thresh, &tracing_max_lat_fops);
|
&tracing_thresh, &tracing_max_lat_fops);
|
||||||
#endif
|
|
||||||
|
|
||||||
trace_create_file("README", 0444, d_tracer,
|
trace_create_file("README", 0444, d_tracer,
|
||||||
NULL, &tracing_readme_fops);
|
NULL, &tracing_readme_fops);
|
||||||
|
|
|
@ -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 nsecs_to_usecs(unsigned long nsecs);
|
||||||
|
|
||||||
|
extern unsigned long tracing_thresh;
|
||||||
|
|
||||||
#ifdef CONFIG_TRACER_MAX_TRACE
|
#ifdef CONFIG_TRACER_MAX_TRACE
|
||||||
extern unsigned long tracing_max_latency;
|
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(struct trace_array *tr, struct task_struct *tsk, int cpu);
|
||||||
void update_max_tr_single(struct trace_array *tr,
|
void update_max_tr_single(struct trace_array *tr,
|
||||||
|
|
|
@ -237,6 +237,14 @@ int trace_graph_entry(struct ftrace_graph_ent *trace)
|
||||||
return ret;
|
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,
|
static void __trace_graph_return(struct trace_array *tr,
|
||||||
struct ftrace_graph_ret *trace,
|
struct ftrace_graph_ret *trace,
|
||||||
unsigned long flags,
|
unsigned long flags,
|
||||||
|
@ -290,13 +298,26 @@ void set_graph_array(struct trace_array *tr)
|
||||||
smp_mb();
|
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)
|
static int graph_trace_init(struct trace_array *tr)
|
||||||
{
|
{
|
||||||
int ret;
|
int ret;
|
||||||
|
|
||||||
set_graph_array(tr);
|
set_graph_array(tr);
|
||||||
ret = register_ftrace_graph(&trace_graph_return,
|
if (tracing_thresh)
|
||||||
&trace_graph_entry);
|
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)
|
if (ret)
|
||||||
return ret;
|
return ret;
|
||||||
tracing_start_cmdline_record();
|
tracing_start_cmdline_record();
|
||||||
|
|
Loading…
Reference in a new issue