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authorTim Bird <tim.bird@am.sony.com>2010-02-25 18:36:43 -0500
committerSteven Rostedt <rostedt@goodmis.org>2010-03-05 21:20:57 -0500
commit0e95017355dcf43031da6d0e360a748717e56df1 (patch)
tree829989bfb494e8d2d773d9dc1bc014b7f28d3bed /kernel/trace
parent1acaa1b2d9b5904c9cce06122990a2d71046ce16 (diff)
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>
Diffstat (limited to 'kernel/trace')
-rw-r--r--kernel/trace/trace.c20
-rw-r--r--kernel/trace/trace.h3
-rw-r--r--kernel/trace/trace_functions_graph.c25
3 files changed, 43 insertions, 5 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 6efd5cb3c252..ababedb4e87f 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -374,6 +374,21 @@ static int __init set_buf_size(char *str)
374} 374}
375__setup("trace_buf_size=", set_buf_size); 375__setup("trace_buf_size=", set_buf_size);
376 376
377static int __init set_tracing_thresh(char *str)
378{
379 unsigned long threshhold;
380 int ret;
381
382 if (!str)
383 return 0;
384 ret = strict_strtoul(str, 0, &threshhold);
385 if (ret < 0)
386 return 0;
387 tracing_thresh = threshhold * 1000;
388 return 1;
389}
390__setup("tracing_thresh=", set_tracing_thresh);
391
377unsigned long nsecs_to_usecs(unsigned long nsecs) 392unsigned long nsecs_to_usecs(unsigned long nsecs)
378{ 393{
379 return nsecs / 1000; 394 return nsecs / 1000;
@@ -579,9 +594,10 @@ static ssize_t trace_seq_to_buffer(struct trace_seq *s, void *buf, size_t cnt)
579static arch_spinlock_t ftrace_max_lock = 594static arch_spinlock_t ftrace_max_lock =
580 (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED; 595 (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
581 596
597unsigned long __read_mostly tracing_thresh;
598
582#ifdef CONFIG_TRACER_MAX_TRACE 599#ifdef CONFIG_TRACER_MAX_TRACE
583unsigned long __read_mostly tracing_max_latency; 600unsigned long __read_mostly tracing_max_latency;
584unsigned long __read_mostly tracing_thresh;
585 601
586/* 602/*
587 * Copy the new maximum trace into the separate maximum-trace 603 * Copy the new maximum trace into the separate maximum-trace
@@ -4248,10 +4264,10 @@ static __init int tracer_init_debugfs(void)
4248#ifdef CONFIG_TRACER_MAX_TRACE 4264#ifdef CONFIG_TRACER_MAX_TRACE
4249 trace_create_file("tracing_max_latency", 0644, d_tracer, 4265 trace_create_file("tracing_max_latency", 0644, d_tracer,
4250 &tracing_max_latency, &tracing_max_lat_fops); 4266 &tracing_max_latency, &tracing_max_lat_fops);
4267#endif
4251 4268
4252 trace_create_file("tracing_thresh", 0644, d_tracer, 4269 trace_create_file("tracing_thresh", 0644, d_tracer,
4253 &tracing_thresh, &tracing_max_lat_fops); 4270 &tracing_thresh, &tracing_max_lat_fops);
4254#endif
4255 4271
4256 trace_create_file("README", 0444, d_tracer, 4272 trace_create_file("README", 0444, d_tracer,
4257 NULL, &tracing_readme_fops); 4273 NULL, &tracing_readme_fops);
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index fd05bcaf91b0..1bc8cd1431d7 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);
396 396
397extern unsigned long nsecs_to_usecs(unsigned long nsecs); 397extern unsigned long nsecs_to_usecs(unsigned long nsecs);
398 398
399extern unsigned long tracing_thresh;
400
399#ifdef CONFIG_TRACER_MAX_TRACE 401#ifdef CONFIG_TRACER_MAX_TRACE
400extern unsigned long tracing_max_latency; 402extern unsigned long tracing_max_latency;
401extern unsigned long tracing_thresh;
402 403
403void update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu); 404void update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu);
404void update_max_tr_single(struct trace_array *tr, 405void 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 7b1f24618d97..e9df04b60267 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)
237 return ret; 237 return ret;
238} 238}
239 239
240int trace_graph_thresh_entry(struct ftrace_graph_ent *trace)
241{
242 if (tracing_thresh)
243 return 1;
244 else
245 return trace_graph_entry(trace);
246}
247
240static void __trace_graph_return(struct trace_array *tr, 248static void __trace_graph_return(struct trace_array *tr,
241 struct ftrace_graph_ret *trace, 249 struct ftrace_graph_ret *trace,
242 unsigned long flags, 250 unsigned long flags,
@@ -290,13 +298,26 @@ void set_graph_array(struct trace_array *tr)
290 smp_mb(); 298 smp_mb();
291} 299}
292 300
301void trace_graph_thresh_return(struct ftrace_graph_ret *trace)
302{
303 if (tracing_thresh &&
304 (trace->rettime - trace->calltime < tracing_thresh))
305 return;
306 else
307 trace_graph_return(trace);
308}
309
293static int graph_trace_init(struct trace_array *tr) 310static int graph_trace_init(struct trace_array *tr)
294{ 311{
295 int ret; 312 int ret;
296 313
297 set_graph_array(tr); 314 set_graph_array(tr);
298 ret = register_ftrace_graph(&trace_graph_return, 315 if (tracing_thresh)
299 &trace_graph_entry); 316 ret = register_ftrace_graph(&trace_graph_thresh_return,
317 &trace_graph_thresh_entry);
318 else
319 ret = register_ftrace_graph(&trace_graph_return,
320 &trace_graph_entry);
300 if (ret) 321 if (ret)
301 return ret; 322 return ret;
302 tracing_start_cmdline_record(); 323 tracing_start_cmdline_record();