cpuidle: add a sysfs entry to disable specific C state for debug purpose.
Some C states of new CPU might be not good. One reason is BIOS might
configure them incorrectly. To help developers root cause it quickly, the
patch adds a new sysfs entry, so developers could disable specific C state
manually.
In addition, C state might have much impact on performance tuning, as it
takes much time to enter/exit C states, which might delay interrupt
processing. With the new debug option, developers could check if a deep C
state could impact performance and how much impact it could cause.
Also add this option in Documentation/cpuidle/sysfs.txt.
[akpm@linux-foundation.org: check kstrtol return value]
Signed-off-by: ShuoX Liu <shuox.liu@intel.com>
Reviewed-by: Yanmin Zhang <yanmin_zhang@intel.com>
Reviewed-and-Tested-by: Deepthi Dharwar <deepthi@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Len Brown <len.brown@intel.com>
diff --git a/drivers/cpuidle/sysfs.c b/drivers/cpuidle/sysfs.c
index 3fe41fe..88032b4 100644
--- a/drivers/cpuidle/sysfs.c
+++ b/drivers/cpuidle/sysfs.c
@@ -11,6 +11,7 @@
#include <linux/sysfs.h>
#include <linux/slab.h>
#include <linux/cpu.h>
+#include <linux/capability.h>
#include "cpuidle.h"
@@ -222,6 +223,9 @@
#define define_one_state_ro(_name, show) \
static struct cpuidle_state_attr attr_##_name = __ATTR(_name, 0444, show, NULL)
+#define define_one_state_rw(_name, show, store) \
+static struct cpuidle_state_attr attr_##_name = __ATTR(_name, 0644, show, store)
+
#define define_show_state_function(_name) \
static ssize_t show_state_##_name(struct cpuidle_state *state, \
struct cpuidle_state_usage *state_usage, char *buf) \
@@ -229,6 +233,24 @@
return sprintf(buf, "%u\n", state->_name);\
}
+#define define_store_state_function(_name) \
+static ssize_t store_state_##_name(struct cpuidle_state *state, \
+ const char *buf, size_t size) \
+{ \
+ long value; \
+ int err; \
+ if (!capable(CAP_SYS_ADMIN)) \
+ return -EPERM; \
+ err = kstrtol(buf, 0, &value); \
+ if (err) \
+ return err; \
+ if (value) \
+ state->disable = 1; \
+ else \
+ state->disable = 0; \
+ return size; \
+}
+
#define define_show_state_ull_function(_name) \
static ssize_t show_state_##_name(struct cpuidle_state *state, \
struct cpuidle_state_usage *state_usage, char *buf) \
@@ -251,6 +273,8 @@
define_show_state_ull_function(time)
define_show_state_str_function(name)
define_show_state_str_function(desc)
+define_show_state_function(disable)
+define_store_state_function(disable)
define_one_state_ro(name, show_state_name);
define_one_state_ro(desc, show_state_desc);
@@ -258,6 +282,7 @@
define_one_state_ro(power, show_state_power_usage);
define_one_state_ro(usage, show_state_usage);
define_one_state_ro(time, show_state_time);
+define_one_state_rw(disable, show_state_disable, store_state_disable);
static struct attribute *cpuidle_state_default_attrs[] = {
&attr_name.attr,
@@ -266,6 +291,7 @@
&attr_power.attr,
&attr_usage.attr,
&attr_time.attr,
+ &attr_disable.attr,
NULL
};
@@ -287,8 +313,22 @@
return ret;
}
+static ssize_t cpuidle_state_store(struct kobject *kobj,
+ struct attribute *attr, const char *buf, size_t size)
+{
+ int ret = -EIO;
+ struct cpuidle_state *state = kobj_to_state(kobj);
+ struct cpuidle_state_attr *cattr = attr_to_stateattr(attr);
+
+ if (cattr->store)
+ ret = cattr->store(state, buf, size);
+
+ return ret;
+}
+
static const struct sysfs_ops cpuidle_state_sysfs_ops = {
.show = cpuidle_state_show,
+ .store = cpuidle_state_store,
};
static void cpuidle_state_sysfs_release(struct kobject *kobj)