diff options
author | ShuoX Liu <shuox.liu@intel.com> | 2012-03-29 00:19:11 +0200 |
---|---|---|
committer | Len Brown <len.brown@intel.com> | 2012-03-30 07:52:58 +0200 |
commit | 3a53396b0381ec9d5180fd8fe7a681c8ce95fd9a (patch) | |
tree | 60a0770554c64250900ccf827ff868b483ae92fe /drivers/cpuidle | |
parent | ARM: davinci: Fix for cpuidle consolidation changes (diff) | |
download | linux-3a53396b0381ec9d5180fd8fe7a681c8ce95fd9a.tar.xz linux-3a53396b0381ec9d5180fd8fe7a681c8ce95fd9a.zip |
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>
Diffstat (limited to 'drivers/cpuidle')
-rw-r--r-- | drivers/cpuidle/cpuidle.c | 1 | ||||
-rw-r--r-- | drivers/cpuidle/governors/menu.c | 5 | ||||
-rw-r--r-- | drivers/cpuidle/sysfs.c | 40 |
3 files changed, 45 insertions, 1 deletions
diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c index 4869b5500234..77304b6b8aef 100644 --- a/drivers/cpuidle/cpuidle.c +++ b/drivers/cpuidle/cpuidle.c @@ -245,6 +245,7 @@ static void poll_idle_init(struct cpuidle_driver *drv) state->power_usage = -1; state->flags = 0; state->enter = poll_idle; + state->disable = 0; } #else static void poll_idle_init(struct cpuidle_driver *drv) {} diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c index ad0952601ae2..5c17ca112fc2 100644 --- a/drivers/cpuidle/governors/menu.c +++ b/drivers/cpuidle/governors/menu.c @@ -280,7 +280,8 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev) * We want to default to C1 (hlt), not to busy polling * unless the timer is happening really really soon. */ - if (data->expected_us > 5) + if (data->expected_us > 5 && + drv->states[CPUIDLE_DRIVER_STATE_START].disable == 0) data->last_state_idx = CPUIDLE_DRIVER_STATE_START; /* @@ -290,6 +291,8 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev) for (i = CPUIDLE_DRIVER_STATE_START; i < drv->state_count; i++) { struct cpuidle_state *s = &drv->states[i]; + if (s->disable) + continue; if (s->target_residency > data->predicted_us) continue; if (s->exit_latency > latency_req) diff --git a/drivers/cpuidle/sysfs.c b/drivers/cpuidle/sysfs.c index 3fe41fe4851a..88032b4dc6d2 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 @@ struct cpuidle_state_attr { #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 @@ static ssize_t show_state_##_name(struct cpuidle_state *state, \ 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(usage) 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(latency, show_state_exit_latency); 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 @@ static struct attribute *cpuidle_state_default_attrs[] = { &attr_power.attr, &attr_usage.attr, &attr_time.attr, + &attr_disable.attr, NULL }; @@ -287,8 +313,22 @@ static ssize_t cpuidle_state_show(struct kobject * kobj, 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) |