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: Dave Hansen <dave@linux.vnet.ibm.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Dave Hansen 2008-10-15 22:01:46 -07:00 committed by Linus Torvalds
parent 0c2d64fb6c
commit 22b8ce9470
4 changed files with 84 additions and 13 deletions

View file

@ -0,0 +1,13 @@
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.

View file

@ -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)

View file

@ -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,

View file

@ -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)