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

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
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.
...@@ -35,7 +35,9 @@ enum profile_type { ...@@ -35,7 +35,9 @@ enum profile_type {
extern int prof_on __read_mostly; extern int prof_on __read_mostly;
/* init basic kernel profiler */ /* 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); void profile_tick(int type);
/* /*
...@@ -84,9 +86,9 @@ struct pt_regs; ...@@ -84,9 +86,9 @@ struct pt_regs;
#define prof_on 0 #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) static inline void profile_tick(int type)
......
...@@ -14,6 +14,7 @@ ...@@ -14,6 +14,7 @@
#include <linux/module.h> #include <linux/module.h>
#include <linux/init.h> #include <linux/init.h>
#include <linux/kexec.h> #include <linux/kexec.h>
#include <linux/profile.h>
#include <linux/sched.h> #include <linux/sched.h>
#define KERNEL_ATTR_RO(_name) \ #define KERNEL_ATTR_RO(_name) \
...@@ -53,6 +54,37 @@ static ssize_t uevent_helper_store(struct kobject *kobj, ...@@ -53,6 +54,37 @@ static ssize_t uevent_helper_store(struct kobject *kobj,
KERNEL_ATTR_RW(uevent_helper); KERNEL_ATTR_RW(uevent_helper);
#endif #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 #ifdef CONFIG_KEXEC
static ssize_t kexec_loaded_show(struct kobject *kobj, static ssize_t kexec_loaded_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf) struct kobj_attribute *attr, char *buf)
...@@ -109,6 +141,9 @@ static struct attribute * kernel_attrs[] = { ...@@ -109,6 +141,9 @@ static struct attribute * kernel_attrs[] = {
&uevent_seqnum_attr.attr, &uevent_seqnum_attr.attr,
&uevent_helper_attr.attr, &uevent_helper_attr.attr,
#endif #endif
#ifdef CONFIG_PROFILING
&profiling_attr.attr,
#endif
#ifdef CONFIG_KEXEC #ifdef CONFIG_KEXEC
&kexec_loaded_attr.attr, &kexec_loaded_attr.attr,
&kexec_crash_loaded_attr.attr, &kexec_crash_loaded_attr.attr,
......
...@@ -22,6 +22,8 @@ ...@@ -22,6 +22,8 @@
#include <linux/cpu.h> #include <linux/cpu.h>
#include <linux/highmem.h> #include <linux/highmem.h>
#include <linux/mutex.h> #include <linux/mutex.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <asm/sections.h> #include <asm/sections.h>
#include <asm/irq_regs.h> #include <asm/irq_regs.h>
#include <asm/ptrace.h> #include <asm/ptrace.h>
...@@ -50,11 +52,11 @@ static DEFINE_PER_CPU(int, cpu_profile_flip); ...@@ -50,11 +52,11 @@ static DEFINE_PER_CPU(int, cpu_profile_flip);
static DEFINE_MUTEX(profile_flip_mutex); static DEFINE_MUTEX(profile_flip_mutex);
#endif /* CONFIG_SMP */ #endif /* CONFIG_SMP */
static int __init profile_setup(char *str) int profile_setup(char *str)
{ {
static char __initdata schedstr[] = "schedule"; static char schedstr[] = "schedule";
static char __initdata sleepstr[] = "sleep"; static char sleepstr[] = "sleep";
static char __initdata kvmstr[] = "kvm"; static char kvmstr[] = "kvm";
int par; int par;
if (!strncmp(str, sleepstr, strlen(sleepstr))) { if (!strncmp(str, sleepstr, strlen(sleepstr))) {
...@@ -100,14 +102,33 @@ static int __init profile_setup(char *str) ...@@ -100,14 +102,33 @@ static int __init profile_setup(char *str)
__setup("profile=", profile_setup); __setup("profile=", profile_setup);
void __init profile_init(void) int profile_init(void)
{ {
int buffer_bytes;
if (!prof_on) if (!prof_on)
return; return 0;
/* only text is profiled */ /* only text is profiled */
prof_len = (_etext - _stext) >> prof_shift; 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 */ /* Profile event notifications */
...@@ -527,7 +548,7 @@ static void __init profile_nop(void *unused) ...@@ -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; int cpu;
...@@ -575,14 +596,14 @@ static int __init create_hash_tables(void) ...@@ -575,14 +596,14 @@ static int __init create_hash_tables(void)
#define create_hash_tables() ({ 0; }) #define create_hash_tables() ({ 0; })
#endif #endif
static int __init create_proc_profile(void) int create_proc_profile(void)
{ {
struct proc_dir_entry *entry; struct proc_dir_entry *entry;
if (!prof_on) if (!prof_on)
return 0; return 0;
if (create_hash_tables()) if (create_hash_tables())
return -1; return -ENOMEM;
entry = proc_create("profile", S_IWUSR | S_IRUGO, entry = proc_create("profile", S_IWUSR | S_IRUGO,
NULL, &proc_profile_operations); NULL, &proc_profile_operations);
if (!entry) if (!entry)
......
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