[RFC/PATCH] ftrace: add set_graph_notrace filter
From: Namhyung Kim
Date: Tue Sep 03 2013 - 01:05:35 EST
From: Namhyung Kim <namhyung.kim@xxxxxxx>
The set_graph_notrace filter is analogous to set_ftrace_notrace and
can be used for eliminating uninteresting part of function graph trace
output. It also works with set_graph_function nicely.
# cd /sys/kernel/debug/tracing/
# echo do_page_fault > set_graph_function
# perf ftrace live true
2) | do_page_fault() {
2) | __do_page_fault() {
2) 0.381 us | down_read_trylock();
2) 0.055 us | __might_sleep();
2) 0.696 us | find_vma();
2) | handle_mm_fault() {
2) | handle_pte_fault() {
2) | __do_fault() {
2) | filemap_fault() {
2) | find_get_page() {
2) 0.033 us | __rcu_read_lock();
2) 0.035 us | __rcu_read_unlock();
2) 1.696 us | }
2) 0.031 us | __might_sleep();
2) 2.831 us | }
2) | _raw_spin_lock() {
2) 0.046 us | add_preempt_count();
2) 0.841 us | }
2) 0.033 us | page_add_file_rmap();
2) | _raw_spin_unlock() {
2) 0.057 us | sub_preempt_count();
2) 0.568 us | }
2) | unlock_page() {
2) 0.084 us | page_waitqueue();
2) 0.126 us | __wake_up_bit();
2) 1.117 us | }
2) 7.729 us | }
2) 8.397 us | }
2) 8.956 us | }
2) 0.085 us | up_read();
2) + 12.745 us | }
2) + 13.401 us | }
...
# echo handle_mm_fault > set_graph_notrace
# perf ftrace live true
1) | do_page_fault() {
1) | __do_page_fault() {
1) 0.205 us | down_read_trylock();
1) 0.041 us | __might_sleep();
1) 0.344 us | find_vma();
1) 0.069 us | up_read();
1) 4.692 us | }
1) 5.311 us | }
...
Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>
---
include/linux/ftrace.h | 1 +
kernel/trace/ftrace.c | 118 ++++++++++++++++++++++++++++++++++-
kernel/trace/trace.h | 23 +++++++
kernel/trace/trace_functions_graph.c | 21 ++++++-
4 files changed, 159 insertions(+), 4 deletions(-)
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 9f15c0064c50..ec85d48619e1 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -721,6 +721,7 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func, int *depth,
extern char __irqentry_text_start[];
extern char __irqentry_text_end[];
+#define FTRACE_NOTRACE_DEPTH 65536
#define FTRACE_RETFUNC_DEPTH 50
#define FTRACE_RETSTACK_ALLOC_SIZE 32
extern int register_ftrace_graph(trace_func_graph_ret_t retfunc,
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index a6d098c6df3f..1b1f3409f788 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -3819,6 +3819,43 @@ static const struct seq_operations ftrace_graph_seq_ops = {
.show = g_show,
};
+int ftrace_graph_notrace_count;
+int ftrace_graph_notrace_enabled;
+unsigned long ftrace_graph_notrace_funcs[FTRACE_GRAPH_MAX_FUNCS] __read_mostly;
+
+static void *
+__n_next(struct seq_file *m, loff_t *pos)
+{
+ if (*pos >= ftrace_graph_notrace_count)
+ return NULL;
+ return &ftrace_graph_notrace_funcs[*pos];
+}
+
+static void *
+n_next(struct seq_file *m, void *v, loff_t *pos)
+{
+ (*pos)++;
+ return __n_next(m, pos);
+}
+
+static void *n_start(struct seq_file *m, loff_t *pos)
+{
+ mutex_lock(&graph_lock);
+
+ /* Nothing, tell g_show to print all functions are enabled */
+ if (!ftrace_graph_notrace_enabled && !*pos)
+ return (void *)1;
+
+ return __n_next(m, pos);
+}
+
+static const struct seq_operations ftrace_graph_notrace_seq_ops = {
+ .start = n_start,
+ .next = n_next,
+ .stop = g_stop,
+ .show = g_show,
+};
+
static int
ftrace_graph_open(struct inode *inode, struct file *file)
{
@@ -3843,6 +3880,30 @@ ftrace_graph_open(struct inode *inode, struct file *file)
}
static int
+ftrace_graph_notrace_open(struct inode *inode, struct file *file)
+{
+ int ret = 0;
+
+ if (unlikely(ftrace_disabled))
+ return -ENODEV;
+
+ mutex_lock(&graph_lock);
+ if ((file->f_mode & FMODE_WRITE) &&
+ (file->f_flags & O_TRUNC)) {
+ ftrace_graph_notrace_enabled = 0;
+ ftrace_graph_notrace_count = 0;
+ memset(ftrace_graph_notrace_funcs, 0,
+ sizeof(ftrace_graph_notrace_funcs));
+ }
+ mutex_unlock(&graph_lock);
+
+ if (file->f_mode & FMODE_READ)
+ ret = seq_open(file, &ftrace_graph_notrace_seq_ops);
+
+ return ret;
+}
+
+static int
ftrace_graph_release(struct inode *inode, struct file *file)
{
if (file->f_mode & FMODE_READ)
@@ -3910,8 +3971,6 @@ out:
if (fail)
return -EINVAL;
- ftrace_graph_filter_enabled = !!(*idx);
-
return 0;
}
@@ -3946,6 +4005,50 @@ ftrace_graph_write(struct file *file, const char __user *ubuf,
ret = read;
+ ftrace_graph_filter_enabled = ftrace_graph_count > 0;
+
+out_free:
+ trace_parser_put(&parser);
+out_unlock:
+ mutex_unlock(&graph_lock);
+
+ return ret;
+}
+
+static ssize_t
+ftrace_graph_notrace_write(struct file *file, const char __user *ubuf,
+ size_t cnt, loff_t *ppos)
+{
+ struct trace_parser parser;
+ ssize_t read, ret;
+
+ if (!cnt)
+ return 0;
+
+ mutex_lock(&graph_lock);
+
+ if (trace_parser_get_init(&parser, FTRACE_BUFF_MAX)) {
+ ret = -ENOMEM;
+ goto out_unlock;
+ }
+
+ read = trace_get_user(&parser, ubuf, cnt, ppos);
+
+ if (read >= 0 && trace_parser_loaded((&parser))) {
+ parser.buffer[parser.idx] = 0;
+
+ /* we allow only one expression at a time */
+ ret = ftrace_set_func(ftrace_graph_notrace_funcs,
+ &ftrace_graph_notrace_count,
+ parser.buffer);
+ if (ret)
+ goto out_free;
+ }
+
+ ret = read;
+
+ ftrace_graph_notrace_enabled = ftrace_graph_notrace_count > 0;
+
out_free:
trace_parser_put(&parser);
out_unlock:
@@ -3961,6 +4064,14 @@ static const struct file_operations ftrace_graph_fops = {
.llseek = ftrace_filter_lseek,
.release = ftrace_graph_release,
};
+
+static const struct file_operations ftrace_graph_notrace_fops = {
+ .open = ftrace_graph_notrace_open,
+ .read = seq_read,
+ .write = ftrace_graph_notrace_write,
+ .llseek = ftrace_filter_lseek,
+ .release = ftrace_graph_release,
+};
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
static __init int ftrace_init_dyn_debugfs(struct dentry *d_tracer)
@@ -3982,6 +4093,9 @@ static __init int ftrace_init_dyn_debugfs(struct dentry *d_tracer)
trace_create_file("set_graph_function", 0444, d_tracer,
NULL,
&ftrace_graph_fops);
+ trace_create_file("set_graph_notrace", 0444, d_tracer,
+ NULL,
+ &ftrace_graph_notrace_fops);
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
return 0;
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index fe39acd4c1aa..797f6f7f3f56 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -732,6 +732,9 @@ extern void __trace_graph_return(struct trace_array *tr,
extern int ftrace_graph_filter_enabled;
extern int ftrace_graph_count;
extern unsigned long ftrace_graph_funcs[FTRACE_GRAPH_MAX_FUNCS];
+extern int ftrace_graph_notrace_enabled;
+extern int ftrace_graph_notrace_count;
+extern unsigned long ftrace_graph_notrace_funcs[FTRACE_GRAPH_MAX_FUNCS];
static inline int ftrace_graph_addr(unsigned long addr)
{
@@ -757,11 +760,31 @@ static inline int ftrace_graph_addr(unsigned long addr)
return 0;
}
+
+static inline int ftrace_graph_notrace_addr(unsigned long addr)
+{
+ int i;
+
+ if (!ftrace_graph_notrace_enabled)
+ return 0;
+
+ for (i = 0; i < ftrace_graph_notrace_count; i++) {
+ if (addr == ftrace_graph_notrace_funcs[i])
+ return 1;
+ }
+
+ return 0;
+}
#else
static inline int ftrace_graph_addr(unsigned long addr)
{
return 1;
}
+
+static inline int ftrace_graph_notrace_addr(unsigned long addr)
+{
+ return 0;
+}
#endif /* CONFIG_DYNAMIC_FTRACE */
#else /* CONFIG_FUNCTION_GRAPH_TRACER */
static inline enum print_line_t
diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index b5c09242683d..3ba240daa5e0 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -114,16 +114,22 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func, int *depth,
return -EBUSY;
}
+ /* The function was filtered out */
+ if (current->curr_ret_stack < -1)
+ return -EBUSY;
+
calltime = trace_clock_local();
index = ++current->curr_ret_stack;
+ if (ftrace_graph_notrace_addr(func))
+ current->curr_ret_stack -= FTRACE_NOTRACE_DEPTH;
barrier();
current->ret_stack[index].ret = ret;
current->ret_stack[index].func = func;
current->ret_stack[index].calltime = calltime;
current->ret_stack[index].subtime = 0;
current->ret_stack[index].fp = frame_pointer;
- *depth = index;
+ *depth = current->curr_ret_stack;
return 0;
}
@@ -137,6 +143,9 @@ ftrace_pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret,
index = current->curr_ret_stack;
+ if (index < 0)
+ index += FTRACE_NOTRACE_DEPTH;
+
if (unlikely(index < 0)) {
ftrace_graph_stop();
WARN_ON(1);
@@ -193,6 +202,10 @@ unsigned long ftrace_return_to_handler(unsigned long frame_pointer)
trace.rettime = trace_clock_local();
barrier();
current->curr_ret_stack--;
+ if (current->curr_ret_stack < -1) {
+ current->curr_ret_stack += FTRACE_NOTRACE_DEPTH;
+ return ret;
+ }
/*
* The trace should run after decrementing the ret counter
@@ -259,10 +272,14 @@ int trace_graph_entry(struct ftrace_graph_ent *trace)
/* trace it when it is-nested-in or is a function enabled. */
if ((!(trace->depth || ftrace_graph_addr(trace->func)) ||
- ftrace_graph_ignore_irqs()) ||
+ ftrace_graph_ignore_irqs()) || (trace->depth < 0) ||
(max_depth && trace->depth >= max_depth))
return 0;
+ /* need to reserve a ret_stack entry to recover the depth */
+ if (ftrace_graph_notrace_addr(trace->func))
+ return 1;
+
local_irq_save(flags);
cpu = raw_smp_processor_id();
data = per_cpu_ptr(tr->trace_buffer.data, cpu);
--
1.7.11.7
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