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| author | Dave Hansen <dave@linux.vnet.ibm.com> | 2008-10-15 22:01:46 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2008-10-16 11:21:31 -0700 |
| commit | 22b8ce94708f7cdf0b04965c6f7443dfd374c35c (patch) | |
| tree | e2d5b60e9b881cf251185b23c3853c8b3e52d42a /kernel/ksysfs.c | |
| parent | 0c2d64fb6cae9aae480f6a46cfe79f8d7d48b59f (diff) | |
| download | lwn-22b8ce94708f7cdf0b04965c6f7443dfd374c35c.tar.gz lwn-22b8ce94708f7cdf0b04965c6f7443dfd374c35c.zip | |
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.c | 35 |
1 files changed, 35 insertions, 0 deletions
diff --git a/kernel/ksysfs.c b/kernel/ksysfs.c index e53bc30e9ba5..08dd8ed86c77 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, |