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Commit b807c3d0 authored by Steven Rostedt's avatar Steven Rostedt Committed by Ingo Molnar
Browse files

ftrace: nmi update statistics 



Impact: add more debug info to /debugfs/tracing/dyn_ftrace_total_info

This patch adds dynamic ftrace NMI update statistics to the
/debugfs/tracing/dyn_ftrace_total_info stat file.

Signed-off-by: default avatarSteven Rostedt <srostedt@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 17666f02

arch/x86/kernel/ftrace.c

+24 −2
Original line number Diff line number Diff line
@@ -91,6 +91,19 @@ static int mod_code_write; 
static void *mod_code_ip;

static void *mod_code_newcode;



static int nmi_wait_count;

static atomic_t nmi_update_count;



int ftrace_arch_read_dyn_info(char *buf, int size)

{

	int r;



	r = snprintf(buf, size, "%u %u",

		     nmi_wait_count,

		     atomic_read(&nmi_update_count));

	return r;

}



static void ftrace_mod_code(void)

{

	/*
@@ -109,8 +122,10 @@ void ftrace_nmi_enter(void) 
	atomic_inc(&in_nmi);

	/* Must have in_nmi seen before reading write flag */

	smp_mb();

	if (mod_code_write)

	if (mod_code_write) {

		ftrace_mod_code();

		atomic_inc(&nmi_update_count);

	}

}



void ftrace_nmi_exit(void)
@@ -122,10 +137,17 @@ void ftrace_nmi_exit(void) 


static void wait_for_nmi(void)

{

	while (atomic_read(&in_nmi))

	int waited = 0;



	while (atomic_read(&in_nmi)) {

		waited = 1;

		cpu_relax();

	}



	if (waited)

		nmi_wait_count++;

}



static int

do_ftrace_mod_code(unsigned long ip, void *new_code)

{

kernel/trace/trace.c

+24 −7
Original line number Diff line number Diff line
@@ -2815,22 +2815,39 @@ static struct file_operations tracing_mark_fops = { 


#ifdef CONFIG_DYNAMIC_FTRACE



#define DYN_INFO_BUF_SIZE 1023

static char ftrace_dyn_info_buffer[DYN_INFO_BUF_SIZE+1];

static DEFINE_MUTEX(dyn_info_mutex);



int __weak ftrace_arch_read_dyn_info(char *buf, int size)

{

	return 0;

}



static ssize_t

tracing_read_long(struct file *filp, char __user *ubuf,

tracing_read_dyn_info(struct file *filp, char __user *ubuf,

		  size_t cnt, loff_t *ppos)

{

	unsigned long *p = filp->private_data;

	char buf[64];

	char *buf = ftrace_dyn_info_buffer;

	int r;



	r = sprintf(buf, "%ld\n", *p);

	mutex_lock(&dyn_info_mutex);

	r = sprintf(buf, "%ld ", *p);



	return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);

	r += ftrace_arch_read_dyn_info(buf+r, DYN_INFO_BUF_SIZE-r);

	buf[r++] = '\n';



	r = simple_read_from_buffer(ubuf, cnt, ppos, buf, r);



	mutex_unlock(&dyn_info_mutex);



	return r;

}



static struct file_operations tracing_read_long_fops = {

static struct file_operations tracing_dyn_info_fops = {

	.open		= tracing_open_generic,

	.read		= tracing_read_long,

	.read		= tracing_read_dyn_info,

};

#endif
@@ -2939,7 +2956,7 @@ static __init int tracer_init_debugfs(void) 
#ifdef CONFIG_DYNAMIC_FTRACE

	entry = debugfs_create_file("dyn_ftrace_total_info", 0444, d_tracer,

				    &ftrace_update_tot_cnt,

				    &tracing_read_long_fops);

				    &tracing_dyn_info_fops);

	if (!entry)

		pr_warning("Could not create debugfs "

			   "'dyn_ftrace_total_info' entry\n");