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authorDave Hansen <dave@linux.vnet.ibm.com>2008-10-15 22:01:46 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-10-16 11:21:31 -0700
commit22b8ce94708f7cdf0b04965c6f7443dfd374c35c (patch)
treee2d5b60e9b881cf251185b23c3853c8b3e52d42a /kernel/ksysfs.c
parent0c2d64fb6cae9aae480f6a46cfe79f8d7d48b59f (diff)
downloadlinux-2.6.34-ux500-22b8ce94708f7cdf0b04965c6f7443dfd374c35c.tar.gz
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>
Diffstat (limited to 'kernel/ksysfs.c')
-rw-r--r--kernel/ksysfs.c35
1 files changed, 35 insertions, 0 deletions
diff --git a/kernel/ksysfs.c b/kernel/ksysfs.c
index e53bc30e9ba..08dd8ed86c7 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 @@ 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,