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>
diff --git a/kernel/ksysfs.c b/kernel/ksysfs.c
index e53bc30..08dd8ed 100644
--- a/kernel/ksysfs.c
+++ b/kernel/ksysfs.c
@@ -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 @@
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 @@
&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,
diff --git a/kernel/profile.c b/kernel/profile.c
index cd26bed..a9e422d 100644
--- a/kernel/profile.c
+++ b/kernel/profile.c
@@ -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_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 @@
__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 int __init create_hash_tables(void)
+static int create_hash_tables(void)
{
int cpu;
@@ -575,14 +596,14 @@
#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)
