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Date: Mon, 30 Sep 2013 23:58:46 -0400
From: Steven Rostedt <rostedt@...dmis.org>
To: Namhyung Kim <namhyung@...nel.org>
Cc: Frederic Weisbecker <fweisbec@...il.com>,
Ingo Molnar <mingo@...nel.org>,
LKML <linux-kernel@...r.kernel.org>,
Namhyung Kim <namhyung.kim@....com>
Subject: Re: [RFC/PATCH] ftrace: add set_graph_notrace filter
On Mon, 2013-09-30 at 16:04 +0900, Namhyung Kim wrote:
> Ping!
Ah I missed this patch. And I'm currently traveling.
I'll start testing it when I get back on Friday, but feel free to ping
me again next Monday.
-- Steve
>
> On Tue, 3 Sep 2013 14:05:08 +0900, Namhyung Kim wrote:
> > From: Namhyung Kim <namhyung.kim@....com>
> >
> > 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@...nel.org>
> > ---
> > 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);
--
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