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Date: Fri, 02 Mar 2012 08:17:33 +0800 From: Yanmin Zhang <yanmin_zhang@...ux.intel.com> To: akpm@...ux-foundation.org Cc: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, "Brown, Len" <len.brown@...el.com>, "Liu, ShuoX" <shuox.liu@...el.com> Subject: Re: Subject: [PATCH] cpuidle: Add a sysfs entry to disable specific C state for debug purpose. On Wed, 2012-02-29 at 04:55 +0000, Liu, ShuoX wrote: > From: ShuoX Liu <shuox.liu@...el.com> > > 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. > > Signed-off-by: ShuoX Liu <shuox.liu@...el.com> Andrew, Would you like to merge the patch into your testing tree? It's useful to help developers debug some issues. Thanks, Yanmin > --- > drivers/cpuidle/cpuidle.c | 1 + > drivers/cpuidle/governors/menu.c | 5 ++++- > drivers/cpuidle/sysfs.c | 34 ++++++++++++++++++++++++++++++++++ > include/linux/cpuidle.h | 1 + > 4 files changed, 40 insertions(+), 1 deletions(-) > > diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c > index 59f4261..7d66d3e 100644 > --- a/drivers/cpuidle/cpuidle.c > +++ b/drivers/cpuidle/cpuidle.c > @@ -197,6 +197,7 @@ 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 ad09526..5c17ca1 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 3fe41fe..1eae29a 100644 > --- a/drivers/cpuidle/sysfs.c > +++ b/drivers/cpuidle/sysfs.c > @@ -222,6 +222,9 @@ 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 +232,19 @@ 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) \ > +{ \ > + int value; \ > + sscanf(buf, "%d", &value); \ > + 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 +267,8 @@ 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 +276,7 @@ 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 +285,7 @@ static struct attribute *cpuidle_state_default_attrs[] = { > &attr_power.attr, > &attr_usage.attr, > &attr_time.attr, > + &attr_disable.attr, > NULL > }; > > @@ -287,8 +307,22 @@ 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) > diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h > index 712abcc..eb150a5 100644 > --- a/include/linux/cpuidle.h > +++ b/include/linux/cpuidle.h > @@ -45,6 +45,7 @@ struct cpuidle_state { > unsigned int exit_latency; /* in US */ > unsigned int power_usage; /* in mW */ > unsigned int target_residency; /* in US */ > + unsigned int disable; > > int (*enter) (struct cpuidle_device *dev, > struct cpuidle_driver *drv, -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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