Commit 22b8ce94 authored by Dave Hansen's avatar Dave Hansen Committed by Linus Torvalds
Browse files

profiling: dynamically enable readprofile at runtime 



Way too often, I have a machine that exhibits some kind of crappy
behavior.  The CPU looks wedged in the kernel or it is spending way too
much system time and I wonder what is responsible.

I try to run readprofile.  But, of course, Ubuntu doesn't enable it by
default.  Dang!

The reason we boot-time enable it is that it takes a big bufffer that we
generally can only bootmem alloc.  But, does it hurt to at least try and
runtime-alloc it?

To use:
echo 2 > /sys/kernel/profile

Then run readprofile like normal.

This should fix the compile issue with allmodconfig.  I've compile-tested
on a bunch more configs now including a few more architectures.

Signed-off-by: default avatarDave Hansen <dave@linux.vnet.ibm.com>
Acked-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 0c2d64fb

Documentation/ABI/testing/sysfs-profiling

0 → 100644
+13 −0
Original line number Diff line number Diff line 
What:		/sys/kernel/profile

Date:		September 2008

Contact:	Dave Hansen <dave@linux.vnet.ibm.com>

Description:

		/sys/kernel/profile is the runtime equivalent

		of the boot-time profile= option.



		You can get the same effect running:



			echo 2 > /sys/kernel/profile



		as you would by issuing profile=2 on the boot

		command line.

include/linux/profile.h

+5 −3
Original line number Diff line number Diff line
@@ -35,7 +35,9 @@ enum profile_type { 
extern int prof_on __read_mostly;



/* init basic kernel profiler */

void __init profile_init(void);

int profile_init(void);

int profile_setup(char *str);

int create_proc_profile(void);

void profile_tick(int type);



/*
@@ -84,9 +86,9 @@ struct pt_regs; 


#define prof_on 0



static inline void profile_init(void)

static inline int profile_init(void)

{

	return;

	return 0;

}



static inline void profile_tick(int type)

kernel/ksysfs.c

+35 −0
Original line number Diff line number Diff line
@@ -14,6 +14,7 @@ 
#include <linux/module.h>

#include <linux/init.h>

#include <linux/kexec.h>

#include <linux/profile.h>

#include <linux/sched.h>



#define KERNEL_ATTR_RO(_name) \
@@ -53,6 +54,37 @@ static ssize_t uevent_helper_store(struct kobject *kobj, 
KERNEL_ATTR_RW(uevent_helper);

#endif



#ifdef CONFIG_PROFILING

static ssize_t profiling_show(struct kobject *kobj,

				  struct kobj_attribute *attr, char *buf)

{

	return sprintf(buf, "%d\n", prof_on);

}

static ssize_t profiling_store(struct kobject *kobj,

				   struct kobj_attribute *attr,

				   const char *buf, size_t count)

{

	int ret;



	if (prof_on)

		return -EEXIST;

	/*

	 * This eventually calls into get_option() which

	 * has a ton of callers and is not const.  It is

	 * easiest to cast it away here.

	 */

	profile_setup((char *)buf);

	ret = profile_init();

	if (ret)

		return ret;

	ret = create_proc_profile();

	if (ret)

		return ret;

	return count;

}

KERNEL_ATTR_RW(profiling);

#endif



#ifdef CONFIG_KEXEC

static ssize_t kexec_loaded_show(struct kobject *kobj,

				 struct kobj_attribute *attr, char *buf)
@@ -109,6 +141,9 @@ static struct attribute * kernel_attrs[] = { 
	&uevent_seqnum_attr.attr,

	&uevent_helper_attr.attr,

#endif

#ifdef CONFIG_PROFILING

	&profiling_attr.attr,

#endif

#ifdef CONFIG_KEXEC

	&kexec_loaded_attr.attr,

	&kexec_crash_loaded_attr.attr,

kernel/profile.c

+31 −10
Original line number Diff line number Diff line
@@ -22,6 +22,8 @@ 
#include <linux/cpu.h>

#include <linux/highmem.h>

#include <linux/mutex.h>

#include <linux/slab.h>

#include <linux/vmalloc.h>

#include <asm/sections.h>

#include <asm/irq_regs.h>

#include <asm/ptrace.h>
@@ -50,11 +52,11 @@ static DEFINE_PER_CPU(int, cpu_profile_flip); 
static DEFINE_MUTEX(profile_flip_mutex);

#endif /* CONFIG_SMP */



static int __init profile_setup(char *str)

int profile_setup(char *str)

{

	static char __initdata schedstr[] = "schedule";

	static char __initdata sleepstr[] = "sleep";

	static char __initdata kvmstr[] = "kvm";

	static char schedstr[] = "schedule";

	static char sleepstr[] = "sleep";

	static char kvmstr[] = "kvm";

	int par;



	if (!strncmp(str, sleepstr, strlen(sleepstr))) {
@@ -100,14 +102,33 @@ static int __init profile_setup(char *str) 
__setup("profile=", profile_setup);





void __init profile_init(void)

int profile_init(void)

{

	int buffer_bytes;

	if (!prof_on)

		return;

		return 0;



	/* only text is profiled */

	prof_len = (_etext - _stext) >> prof_shift;

	prof_buffer = alloc_bootmem(prof_len*sizeof(atomic_t));

	buffer_bytes = prof_len*sizeof(atomic_t);

	if (!slab_is_available()) {

		prof_buffer = alloc_bootmem(buffer_bytes);

		return 0;

	}



	prof_buffer = kzalloc(buffer_bytes, GFP_KERNEL);

	if (prof_buffer)

		return 0;



	prof_buffer = alloc_pages_exact(buffer_bytes, GFP_KERNEL|__GFP_ZERO);

	if (prof_buffer)

		return 0;



	prof_buffer = vmalloc(buffer_bytes);

	if (prof_buffer)

		return 0;



	return -ENOMEM;

}



/* Profile event notifications */
@@ -527,7 +548,7 @@ static void __init profile_nop(void *unused) 
{

}



static int __init create_hash_tables(void)

static int create_hash_tables(void)

{

	int cpu;
@@ -575,14 +596,14 @@ out_cleanup: 
#define create_hash_tables()			({ 0; })

#endif



static int __init create_proc_profile(void)

int create_proc_profile(void)

{

	struct proc_dir_entry *entry;



	if (!prof_on)

		return 0;

	if (create_hash_tables())

		return -1;

		return -ENOMEM;

	entry = proc_create("profile", S_IWUSR | S_IRUGO,

			    NULL, &proc_profile_operations);

	if (!entry)

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