* [PATCH 0/2] new cpumask for hotpluggable CPUs
@ 2011-08-10 1:33 Mike Turquette
2011-08-10 1:33 ` [PATCH 1/2] cpumask: introduce " Mike Turquette
` (3 more replies)
0 siblings, 4 replies; 13+ messages in thread
From: Mike Turquette @ 2011-08-10 1:33 UTC (permalink / raw)
To: linux-kernel; +Cc: linux-pm, linaro-dev, patches, Mike Turquette
This patch series introduces a new cpumask which tracks CPUs that
support hotplugging. The purpose of this patch series is to provide a
simple method for kernel code to know which CPUs can be hotplugged and
which ones cannot. Potential users of this code might be a thermal
mitigation technique which uses hotplug to lower temperature, or a power
capping mechanism which uses hotplug to lower power consumption.
All the of usual cpumask helper functions are created for this new mask.
The second patch in this series simply sets the bit for elligible CPUs
while they are being registered. The cpumask itself is static after
boot and should not change (like the possbile mask).
Mike Turquette (2):
cpumask: introduce cpumask for hotpluggable CPUs
cpu: update cpu_hotpluggable_mask in register_cpu
drivers/base/cpu.c | 4 +++-
include/linux/cpumask.h | 27 ++++++++++++++++++++++-----
kernel/cpu.c | 18 ++++++++++++++++++
3 files changed, 43 insertions(+), 6 deletions(-)
--
1.7.4.1
^ permalink raw reply [flat|nested] 13+ messages in thread
* [PATCH 1/2] cpumask: introduce cpumask for hotpluggable CPUs
2011-08-10 1:33 [PATCH 0/2] new cpumask for hotpluggable CPUs Mike Turquette
@ 2011-08-10 1:33 ` Mike Turquette
2011-08-10 1:33 ` Mike Turquette
` (2 subsequent siblings)
3 siblings, 0 replies; 13+ messages in thread
From: Mike Turquette @ 2011-08-10 1:33 UTC (permalink / raw)
To: linux-kernel; +Cc: linux-pm, linaro-dev, patches
On some platforms it is possible to have some CPUs which support CPU
hotplug and some which do not. Currently the prescence of an 'online'
sysfs entry in userspace is adequate for applications to know that a CPU
supports hotplug, but there is no convenient way to make the same
determination in the kernel.
To better model this relationship this patch introduces a new cpumask to
track CPUs that support CPU hotplug operations.
This new cpumask is populated at boot-time and remains static for the
life of the machine. Bits set in the mask indicate a CPU which supports
hotplug, but make no guarantees about whether that CPU is currently
online or not. Likewise a cleared bit in the mask indicates either a
CPU which cannot hotplug or a lack of a populated CPU.
The purpose of this new cpumask is to aid kernel code which uses CPU to
take CPUs online and offline. Possible uses are as a thermal event
mitigation technique or as a power capping mechanism.
Signed-off-by: Mike Turquette <mturquette@ti.com>
---
include/linux/cpumask.h | 27 ++++++++++++++++++++++-----
kernel/cpu.c | 18 ++++++++++++++++++
2 files changed, 40 insertions(+), 5 deletions(-)
diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
index b24ac56..9eed444 100644
--- a/include/linux/cpumask.h
+++ b/include/linux/cpumask.h
@@ -39,10 +39,11 @@ extern int nr_cpu_ids;
* The following particular system cpumasks and operations manage
* possible, present, active and online cpus.
*
- * cpu_possible_mask- has bit 'cpu' set iff cpu is populatable
- * cpu_present_mask - has bit 'cpu' set iff cpu is populated
- * cpu_online_mask - has bit 'cpu' set iff cpu available to scheduler
- * cpu_active_mask - has bit 'cpu' set iff cpu available to migration
+ * cpu_possible_mask - has bit 'cpu' set iff cpu is populatable
+ * cpu_hotpluggable_mask - has bit 'cpu' set iff cpu is hotpluggable
+ * cpu_present_mask - has bit 'cpu' set iff cpu is populated
+ * cpu_online_mask - has bit 'cpu' set iff cpu available to scheduler
+ * cpu_active_mask - has bit 'cpu' set iff cpu available to migration
*
* If !CONFIG_HOTPLUG_CPU, present == possible, and active == online.
*
@@ -51,7 +52,11 @@ extern int nr_cpu_ids;
* life of that system boot. The cpu_present_mask is dynamic(*),
* representing which CPUs are currently plugged in. And
* cpu_online_mask is the dynamic subset of cpu_present_mask,
- * indicating those CPUs available for scheduling.
+ * indicating those CPUs available for scheduling. The
+ * cpu_hotpluggable_mask is also fixed at boot time, as the set of CPU
+ * id's which are possible AND can hotplug. Cleared bits in this mask
+ * mean that either the CPU is not possible, or it is possible but does
+ * not support CPU hotplug operations.
*
* If HOTPLUG is enabled, then cpu_possible_mask is forced to have
* all NR_CPUS bits set, otherwise it is just the set of CPUs that
@@ -61,6 +66,9 @@ extern int nr_cpu_ids;
* depending on what ACPI reports as currently plugged in, otherwise
* cpu_present_mask is just a copy of cpu_possible_mask.
*
+ * If CONFIG_HOTPLUG_CPU is enabled, then cpu_hotpluggable_mask matches
+ * the description above, otherwise it is the empty set.
+ *
* (*) Well, cpu_present_mask is dynamic in the hotplug case. If not
* hotplug, it's a copy of cpu_possible_mask, hence fixed at boot.
*
@@ -76,6 +84,7 @@ extern int nr_cpu_ids;
*/
extern const struct cpumask *const cpu_possible_mask;
+extern const struct cpumask *const cpu_hotpluggable_mask;
extern const struct cpumask *const cpu_online_mask;
extern const struct cpumask *const cpu_present_mask;
extern const struct cpumask *const cpu_active_mask;
@@ -85,19 +94,23 @@ extern const struct cpumask *const cpu_active_mask;
#define num_possible_cpus() cpumask_weight(cpu_possible_mask)
#define num_present_cpus() cpumask_weight(cpu_present_mask)
#define num_active_cpus() cpumask_weight(cpu_active_mask)
+#define num_hotpluggable_cpus() cpumask_weight(cpu_hotpluggable_mask)
#define cpu_online(cpu) cpumask_test_cpu((cpu), cpu_online_mask)
#define cpu_possible(cpu) cpumask_test_cpu((cpu), cpu_possible_mask)
#define cpu_present(cpu) cpumask_test_cpu((cpu), cpu_present_mask)
#define cpu_active(cpu) cpumask_test_cpu((cpu), cpu_active_mask)
+#define cpu_hotpluggable(cpu) cpumask_test_cpu((cpu, cpu_hotpluggable_mask)
#else
#define num_online_cpus() 1U
#define num_possible_cpus() 1U
#define num_present_cpus() 1U
#define num_active_cpus() 1U
+#define num_hotpluggable_cpus() 0
#define cpu_online(cpu) ((cpu) == 0)
#define cpu_possible(cpu) ((cpu) == 0)
#define cpu_present(cpu) ((cpu) == 0)
#define cpu_active(cpu) ((cpu) == 0)
+#define cpu_hotpluggable(cpu) 0
#endif
/* verify cpu argument to cpumask_* operators */
@@ -678,16 +691,20 @@ extern const DECLARE_BITMAP(cpu_all_bits, NR_CPUS);
#define cpu_none_mask to_cpumask(cpu_bit_bitmap[0])
#define for_each_possible_cpu(cpu) for_each_cpu((cpu), cpu_possible_mask)
+#define for_each_hotpluggable_cpu(cpu) \
+ for_each_cpu((cpu), cpu_hotpluggable_mask)
#define for_each_online_cpu(cpu) for_each_cpu((cpu), cpu_online_mask)
#define for_each_present_cpu(cpu) for_each_cpu((cpu), cpu_present_mask)
/* Wrappers for arch boot code to manipulate normally-constant masks */
void set_cpu_possible(unsigned int cpu, bool possible);
+void set_cpu_hotpluggable(unsigned int cpu, bool hotpluggable);
void set_cpu_present(unsigned int cpu, bool present);
void set_cpu_online(unsigned int cpu, bool online);
void set_cpu_active(unsigned int cpu, bool active);
void init_cpu_present(const struct cpumask *src);
void init_cpu_possible(const struct cpumask *src);
+void init_cpu_hotpluggable(const struct cpumask *src);
void init_cpu_online(const struct cpumask *src);
/**
diff --git a/kernel/cpu.c b/kernel/cpu.c
index 12b7458..8c397c9 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -536,6 +536,11 @@ static DECLARE_BITMAP(cpu_possible_bits, CONFIG_NR_CPUS) __read_mostly;
const struct cpumask *const cpu_possible_mask = to_cpumask(cpu_possible_bits);
EXPORT_SYMBOL(cpu_possible_mask);
+static DECLARE_BITMAP(cpu_hotpluggable_bits, CONFIG_NR_CPUS) __read_mostly;
+const struct cpumask *const cpu_hotpluggable_mask =
+ to_cpumask(cpu_hotpluggable_bits);
+EXPORT_SYMBOL(cpu_hotpluggable_mask);
+
static DECLARE_BITMAP(cpu_online_bits, CONFIG_NR_CPUS) __read_mostly;
const struct cpumask *const cpu_online_mask = to_cpumask(cpu_online_bits);
EXPORT_SYMBOL(cpu_online_mask);
@@ -556,6 +561,14 @@ void set_cpu_possible(unsigned int cpu, bool possible)
cpumask_clear_cpu(cpu, to_cpumask(cpu_possible_bits));
}
+void set_cpu_hotpluggable(unsigned int cpu, bool hotpluggable)
+{
+ if (hotpluggable)
+ cpumask_set_cpu(cpu, to_cpumask(cpu_hotpluggable_bits));
+ else
+ cpumask_clear_cpu(cpu, to_cpumask(cpu_hotpluggable_bits));
+}
+
void set_cpu_present(unsigned int cpu, bool present)
{
if (present)
@@ -590,6 +603,11 @@ void init_cpu_possible(const struct cpumask *src)
cpumask_copy(to_cpumask(cpu_possible_bits), src);
}
+void init_cpu_hotpluggable(const struct cpumask *src)
+{
+ cpumask_copy(to_cpumask(cpu_hotpluggable_bits), src);
+}
+
void init_cpu_online(const struct cpumask *src)
{
cpumask_copy(to_cpumask(cpu_online_bits), src);
--
1.7.4.1
^ permalink raw reply related [flat|nested] 13+ messages in thread
* [PATCH 1/2] cpumask: introduce cpumask for hotpluggable CPUs
2011-08-10 1:33 [PATCH 0/2] new cpumask for hotpluggable CPUs Mike Turquette
2011-08-10 1:33 ` [PATCH 1/2] cpumask: introduce " Mike Turquette
@ 2011-08-10 1:33 ` Mike Turquette
2011-08-10 2:01 ` Christian Robottom Reis
` (3 more replies)
2011-08-10 1:33 ` [PATCH 2/2] cpu: update cpu_hotpluggable_mask in register_cpu Mike Turquette
2011-08-10 1:33 ` Mike Turquette
3 siblings, 4 replies; 13+ messages in thread
From: Mike Turquette @ 2011-08-10 1:33 UTC (permalink / raw)
To: linux-kernel; +Cc: linux-pm, linaro-dev, patches, Mike Turquette
On some platforms it is possible to have some CPUs which support CPU
hotplug and some which do not. Currently the prescence of an 'online'
sysfs entry in userspace is adequate for applications to know that a CPU
supports hotplug, but there is no convenient way to make the same
determination in the kernel.
To better model this relationship this patch introduces a new cpumask to
track CPUs that support CPU hotplug operations.
This new cpumask is populated at boot-time and remains static for the
life of the machine. Bits set in the mask indicate a CPU which supports
hotplug, but make no guarantees about whether that CPU is currently
online or not. Likewise a cleared bit in the mask indicates either a
CPU which cannot hotplug or a lack of a populated CPU.
The purpose of this new cpumask is to aid kernel code which uses CPU to
take CPUs online and offline. Possible uses are as a thermal event
mitigation technique or as a power capping mechanism.
Signed-off-by: Mike Turquette <mturquette@ti.com>
---
include/linux/cpumask.h | 27 ++++++++++++++++++++++-----
kernel/cpu.c | 18 ++++++++++++++++++
2 files changed, 40 insertions(+), 5 deletions(-)
diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
index b24ac56..9eed444 100644
--- a/include/linux/cpumask.h
+++ b/include/linux/cpumask.h
@@ -39,10 +39,11 @@ extern int nr_cpu_ids;
* The following particular system cpumasks and operations manage
* possible, present, active and online cpus.
*
- * cpu_possible_mask- has bit 'cpu' set iff cpu is populatable
- * cpu_present_mask - has bit 'cpu' set iff cpu is populated
- * cpu_online_mask - has bit 'cpu' set iff cpu available to scheduler
- * cpu_active_mask - has bit 'cpu' set iff cpu available to migration
+ * cpu_possible_mask - has bit 'cpu' set iff cpu is populatable
+ * cpu_hotpluggable_mask - has bit 'cpu' set iff cpu is hotpluggable
+ * cpu_present_mask - has bit 'cpu' set iff cpu is populated
+ * cpu_online_mask - has bit 'cpu' set iff cpu available to scheduler
+ * cpu_active_mask - has bit 'cpu' set iff cpu available to migration
*
* If !CONFIG_HOTPLUG_CPU, present == possible, and active == online.
*
@@ -51,7 +52,11 @@ extern int nr_cpu_ids;
* life of that system boot. The cpu_present_mask is dynamic(*),
* representing which CPUs are currently plugged in. And
* cpu_online_mask is the dynamic subset of cpu_present_mask,
- * indicating those CPUs available for scheduling.
+ * indicating those CPUs available for scheduling. The
+ * cpu_hotpluggable_mask is also fixed at boot time, as the set of CPU
+ * id's which are possible AND can hotplug. Cleared bits in this mask
+ * mean that either the CPU is not possible, or it is possible but does
+ * not support CPU hotplug operations.
*
* If HOTPLUG is enabled, then cpu_possible_mask is forced to have
* all NR_CPUS bits set, otherwise it is just the set of CPUs that
@@ -61,6 +66,9 @@ extern int nr_cpu_ids;
* depending on what ACPI reports as currently plugged in, otherwise
* cpu_present_mask is just a copy of cpu_possible_mask.
*
+ * If CONFIG_HOTPLUG_CPU is enabled, then cpu_hotpluggable_mask matches
+ * the description above, otherwise it is the empty set.
+ *
* (*) Well, cpu_present_mask is dynamic in the hotplug case. If not
* hotplug, it's a copy of cpu_possible_mask, hence fixed at boot.
*
@@ -76,6 +84,7 @@ extern int nr_cpu_ids;
*/
extern const struct cpumask *const cpu_possible_mask;
+extern const struct cpumask *const cpu_hotpluggable_mask;
extern const struct cpumask *const cpu_online_mask;
extern const struct cpumask *const cpu_present_mask;
extern const struct cpumask *const cpu_active_mask;
@@ -85,19 +94,23 @@ extern const struct cpumask *const cpu_active_mask;
#define num_possible_cpus() cpumask_weight(cpu_possible_mask)
#define num_present_cpus() cpumask_weight(cpu_present_mask)
#define num_active_cpus() cpumask_weight(cpu_active_mask)
+#define num_hotpluggable_cpus() cpumask_weight(cpu_hotpluggable_mask)
#define cpu_online(cpu) cpumask_test_cpu((cpu), cpu_online_mask)
#define cpu_possible(cpu) cpumask_test_cpu((cpu), cpu_possible_mask)
#define cpu_present(cpu) cpumask_test_cpu((cpu), cpu_present_mask)
#define cpu_active(cpu) cpumask_test_cpu((cpu), cpu_active_mask)
+#define cpu_hotpluggable(cpu) cpumask_test_cpu((cpu, cpu_hotpluggable_mask)
#else
#define num_online_cpus() 1U
#define num_possible_cpus() 1U
#define num_present_cpus() 1U
#define num_active_cpus() 1U
+#define num_hotpluggable_cpus() 0
#define cpu_online(cpu) ((cpu) == 0)
#define cpu_possible(cpu) ((cpu) == 0)
#define cpu_present(cpu) ((cpu) == 0)
#define cpu_active(cpu) ((cpu) == 0)
+#define cpu_hotpluggable(cpu) 0
#endif
/* verify cpu argument to cpumask_* operators */
@@ -678,16 +691,20 @@ extern const DECLARE_BITMAP(cpu_all_bits, NR_CPUS);
#define cpu_none_mask to_cpumask(cpu_bit_bitmap[0])
#define for_each_possible_cpu(cpu) for_each_cpu((cpu), cpu_possible_mask)
+#define for_each_hotpluggable_cpu(cpu) \
+ for_each_cpu((cpu), cpu_hotpluggable_mask)
#define for_each_online_cpu(cpu) for_each_cpu((cpu), cpu_online_mask)
#define for_each_present_cpu(cpu) for_each_cpu((cpu), cpu_present_mask)
/* Wrappers for arch boot code to manipulate normally-constant masks */
void set_cpu_possible(unsigned int cpu, bool possible);
+void set_cpu_hotpluggable(unsigned int cpu, bool hotpluggable);
void set_cpu_present(unsigned int cpu, bool present);
void set_cpu_online(unsigned int cpu, bool online);
void set_cpu_active(unsigned int cpu, bool active);
void init_cpu_present(const struct cpumask *src);
void init_cpu_possible(const struct cpumask *src);
+void init_cpu_hotpluggable(const struct cpumask *src);
void init_cpu_online(const struct cpumask *src);
/**
diff --git a/kernel/cpu.c b/kernel/cpu.c
index 12b7458..8c397c9 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -536,6 +536,11 @@ static DECLARE_BITMAP(cpu_possible_bits, CONFIG_NR_CPUS) __read_mostly;
const struct cpumask *const cpu_possible_mask = to_cpumask(cpu_possible_bits);
EXPORT_SYMBOL(cpu_possible_mask);
+static DECLARE_BITMAP(cpu_hotpluggable_bits, CONFIG_NR_CPUS) __read_mostly;
+const struct cpumask *const cpu_hotpluggable_mask =
+ to_cpumask(cpu_hotpluggable_bits);
+EXPORT_SYMBOL(cpu_hotpluggable_mask);
+
static DECLARE_BITMAP(cpu_online_bits, CONFIG_NR_CPUS) __read_mostly;
const struct cpumask *const cpu_online_mask = to_cpumask(cpu_online_bits);
EXPORT_SYMBOL(cpu_online_mask);
@@ -556,6 +561,14 @@ void set_cpu_possible(unsigned int cpu, bool possible)
cpumask_clear_cpu(cpu, to_cpumask(cpu_possible_bits));
}
+void set_cpu_hotpluggable(unsigned int cpu, bool hotpluggable)
+{
+ if (hotpluggable)
+ cpumask_set_cpu(cpu, to_cpumask(cpu_hotpluggable_bits));
+ else
+ cpumask_clear_cpu(cpu, to_cpumask(cpu_hotpluggable_bits));
+}
+
void set_cpu_present(unsigned int cpu, bool present)
{
if (present)
@@ -590,6 +603,11 @@ void init_cpu_possible(const struct cpumask *src)
cpumask_copy(to_cpumask(cpu_possible_bits), src);
}
+void init_cpu_hotpluggable(const struct cpumask *src)
+{
+ cpumask_copy(to_cpumask(cpu_hotpluggable_bits), src);
+}
+
void init_cpu_online(const struct cpumask *src)
{
cpumask_copy(to_cpumask(cpu_online_bits), src);
--
1.7.4.1
^ permalink raw reply related [flat|nested] 13+ messages in thread
* [PATCH 2/2] cpu: update cpu_hotpluggable_mask in register_cpu
2011-08-10 1:33 [PATCH 0/2] new cpumask for hotpluggable CPUs Mike Turquette
2011-08-10 1:33 ` [PATCH 1/2] cpumask: introduce " Mike Turquette
2011-08-10 1:33 ` Mike Turquette
@ 2011-08-10 1:33 ` Mike Turquette
2011-08-10 1:33 ` Mike Turquette
3 siblings, 0 replies; 13+ messages in thread
From: Mike Turquette @ 2011-08-10 1:33 UTC (permalink / raw)
To: linux-kernel; +Cc: linux-pm, linaro-dev, patches
Update the cpu_hotpluggable_mask for each registered CPU which supports
hotplug. This makes it trivial for kernel code to know which CPUs
support hotplug operations.
Signed-off-by: Mike Turquette <mturquette@ti.com>
---
drivers/base/cpu.c | 4 +++-
1 files changed, 3 insertions(+), 1 deletions(-)
diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c
index 251acea..91ddcf8 100644
--- a/drivers/base/cpu.c
+++ b/drivers/base/cpu.c
@@ -224,8 +224,10 @@ int __cpuinit register_cpu(struct cpu *cpu, int num)
error = sysdev_register(&cpu->sysdev);
- if (!error && cpu->hotpluggable)
+ if (!error && cpu->hotpluggable) {
register_cpu_control(cpu);
+ set_cpu_hotpluggable(num, true);
+ }
if (!error)
per_cpu(cpu_sys_devices, num) = &cpu->sysdev;
if (!error)
--
1.7.4.1
^ permalink raw reply related [flat|nested] 13+ messages in thread
* [PATCH 2/2] cpu: update cpu_hotpluggable_mask in register_cpu
2011-08-10 1:33 [PATCH 0/2] new cpumask for hotpluggable CPUs Mike Turquette
` (2 preceding siblings ...)
2011-08-10 1:33 ` [PATCH 2/2] cpu: update cpu_hotpluggable_mask in register_cpu Mike Turquette
@ 2011-08-10 1:33 ` Mike Turquette
3 siblings, 0 replies; 13+ messages in thread
From: Mike Turquette @ 2011-08-10 1:33 UTC (permalink / raw)
To: linux-kernel; +Cc: linux-pm, linaro-dev, patches, Mike Turquette
Update the cpu_hotpluggable_mask for each registered CPU which supports
hotplug. This makes it trivial for kernel code to know which CPUs
support hotplug operations.
Signed-off-by: Mike Turquette <mturquette@ti.com>
---
drivers/base/cpu.c | 4 +++-
1 files changed, 3 insertions(+), 1 deletions(-)
diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c
index 251acea..91ddcf8 100644
--- a/drivers/base/cpu.c
+++ b/drivers/base/cpu.c
@@ -224,8 +224,10 @@ int __cpuinit register_cpu(struct cpu *cpu, int num)
error = sysdev_register(&cpu->sysdev);
- if (!error && cpu->hotpluggable)
+ if (!error && cpu->hotpluggable) {
register_cpu_control(cpu);
+ set_cpu_hotpluggable(num, true);
+ }
if (!error)
per_cpu(cpu_sys_devices, num) = &cpu->sysdev;
if (!error)
--
1.7.4.1
^ permalink raw reply related [flat|nested] 13+ messages in thread
* Re: [PATCH 1/2] cpumask: introduce cpumask for hotpluggable CPUs
2011-08-10 1:33 ` Mike Turquette
@ 2011-08-10 2:01 ` Christian Robottom Reis
2011-08-10 2:01 ` Christian Robottom Reis
` (2 subsequent siblings)
3 siblings, 0 replies; 13+ messages in thread
From: Christian Robottom Reis @ 2011-08-10 2:01 UTC (permalink / raw)
To: Mike Turquette; +Cc: linux-pm, linaro-dev, linux-kernel, patches
On Tue, Aug 09, 2011 at 06:33:26PM -0700, Mike Turquette wrote:
> - * cpu_possible_mask- has bit 'cpu' set iff cpu is populatable
> - * cpu_present_mask - has bit 'cpu' set iff cpu is populated
> - * cpu_online_mask - has bit 'cpu' set iff cpu available to scheduler
> - * cpu_active_mask - has bit 'cpu' set iff cpu available to migration
> + * cpu_possible_mask - has bit 'cpu' set iff cpu is populatable
> + * cpu_hotpluggable_mask - has bit 'cpu' set iff cpu is hotpluggable
> + * cpu_present_mask - has bit 'cpu' set iff cpu is populated
> + * cpu_online_mask - has bit 'cpu' set iff cpu available to scheduler
> + * cpu_active_mask - has bit 'cpu' set iff cpu available to migration
Why not fix the 'iff' typo while you're here?
--
Christian Robottom Reis, Engineering VP
Brazil (GMT-3) | [+55] 16 9112 6430 | [+1] 612 216 4935
Linaro.org: Open Source Software for ARM SoCs
^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [PATCH 1/2] cpumask: introduce cpumask for hotpluggable CPUs
2011-08-10 1:33 ` Mike Turquette
2011-08-10 2:01 ` Christian Robottom Reis
@ 2011-08-10 2:01 ` Christian Robottom Reis
2011-08-10 2:03 ` Turquette, Mike
2011-08-10 2:03 ` Turquette, Mike
2011-08-10 8:42 ` Amit Kucheria
2011-08-10 8:42 ` Amit Kucheria
3 siblings, 2 replies; 13+ messages in thread
From: Christian Robottom Reis @ 2011-08-10 2:01 UTC (permalink / raw)
To: Mike Turquette; +Cc: linux-kernel, linux-pm, linaro-dev, patches
On Tue, Aug 09, 2011 at 06:33:26PM -0700, Mike Turquette wrote:
> - * cpu_possible_mask- has bit 'cpu' set iff cpu is populatable
> - * cpu_present_mask - has bit 'cpu' set iff cpu is populated
> - * cpu_online_mask - has bit 'cpu' set iff cpu available to scheduler
> - * cpu_active_mask - has bit 'cpu' set iff cpu available to migration
> + * cpu_possible_mask - has bit 'cpu' set iff cpu is populatable
> + * cpu_hotpluggable_mask - has bit 'cpu' set iff cpu is hotpluggable
> + * cpu_present_mask - has bit 'cpu' set iff cpu is populated
> + * cpu_online_mask - has bit 'cpu' set iff cpu available to scheduler
> + * cpu_active_mask - has bit 'cpu' set iff cpu available to migration
Why not fix the 'iff' typo while you're here?
--
Christian Robottom Reis, Engineering VP
Brazil (GMT-3) | [+55] 16 9112 6430 | [+1] 612 216 4935
Linaro.org: Open Source Software for ARM SoCs
^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [PATCH 1/2] cpumask: introduce cpumask for hotpluggable CPUs
2011-08-10 2:01 ` Christian Robottom Reis
2011-08-10 2:03 ` Turquette, Mike
@ 2011-08-10 2:03 ` Turquette, Mike
1 sibling, 0 replies; 13+ messages in thread
From: Turquette, Mike @ 2011-08-10 2:03 UTC (permalink / raw)
To: Christian Robottom Reis; +Cc: linux-pm, linaro-dev, linux-kernel, patches
On Tue, Aug 9, 2011 at 7:01 PM, Christian Robottom Reis <kiko@linaro.org> wrote:
> On Tue, Aug 09, 2011 at 06:33:26PM -0700, Mike Turquette wrote:
>> - * cpu_possible_mask- has bit 'cpu' set iff cpu is populatable
>> - * cpu_present_mask - has bit 'cpu' set iff cpu is populated
>> - * cpu_online_mask - has bit 'cpu' set iff cpu available to scheduler
>> - * cpu_active_mask - has bit 'cpu' set iff cpu available to migration
>> + * cpu_possible_mask - has bit 'cpu' set iff cpu is populatable
>> + * cpu_hotpluggable_mask - has bit 'cpu' set iff cpu is hotpluggable
>> + * cpu_present_mask - has bit 'cpu' set iff cpu is populated
>> + * cpu_online_mask - has bit 'cpu' set iff cpu available to scheduler
>> + * cpu_active_mask - has bit 'cpu' set iff cpu available to migration
>
> Why not fix the 'iff' typo while you're here?
iff = if and only if
http://en.wikipedia.org/wiki/If_and_only_if
Thanks!
Mike
> Christian Robottom Reis, Engineering VP
> Brazil (GMT-3) | [+55] 16 9112 6430 | [+1] 612 216 4935
> Linaro.org: Open Source Software for ARM SoCs
>
^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [PATCH 1/2] cpumask: introduce cpumask for hotpluggable CPUs
2011-08-10 2:01 ` Christian Robottom Reis
@ 2011-08-10 2:03 ` Turquette, Mike
2011-08-10 2:03 ` Turquette, Mike
1 sibling, 0 replies; 13+ messages in thread
From: Turquette, Mike @ 2011-08-10 2:03 UTC (permalink / raw)
To: Christian Robottom Reis; +Cc: linux-kernel, linux-pm, linaro-dev, patches
On Tue, Aug 9, 2011 at 7:01 PM, Christian Robottom Reis <kiko@linaro.org> wrote:
> On Tue, Aug 09, 2011 at 06:33:26PM -0700, Mike Turquette wrote:
>> - * cpu_possible_mask- has bit 'cpu' set iff cpu is populatable
>> - * cpu_present_mask - has bit 'cpu' set iff cpu is populated
>> - * cpu_online_mask - has bit 'cpu' set iff cpu available to scheduler
>> - * cpu_active_mask - has bit 'cpu' set iff cpu available to migration
>> + * cpu_possible_mask - has bit 'cpu' set iff cpu is populatable
>> + * cpu_hotpluggable_mask - has bit 'cpu' set iff cpu is hotpluggable
>> + * cpu_present_mask - has bit 'cpu' set iff cpu is populated
>> + * cpu_online_mask - has bit 'cpu' set iff cpu available to scheduler
>> + * cpu_active_mask - has bit 'cpu' set iff cpu available to migration
>
> Why not fix the 'iff' typo while you're here?
iff = if and only if
http://en.wikipedia.org/wiki/If_and_only_if
Thanks!
Mike
> Christian Robottom Reis, Engineering VP
> Brazil (GMT-3) | [+55] 16 9112 6430 | [+1] 612 216 4935
> Linaro.org: Open Source Software for ARM SoCs
>
^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [PATCH 1/2] cpumask: introduce cpumask for hotpluggable CPUs
2011-08-10 1:33 ` Mike Turquette
2011-08-10 2:01 ` Christian Robottom Reis
2011-08-10 2:01 ` Christian Robottom Reis
@ 2011-08-10 8:42 ` Amit Kucheria
2011-08-10 8:42 ` Amit Kucheria
3 siblings, 0 replies; 13+ messages in thread
From: Amit Kucheria @ 2011-08-10 8:42 UTC (permalink / raw)
To: Mike Turquette; +Cc: linux-pm, linaro-dev, linux-kernel, patches
On 11 Aug 09, Mike Turquette wrote:
> On some platforms it is possible to have some CPUs which support CPU
> hotplug and some which do not. Currently the prescence of an 'online'
> sysfs entry in userspace is adequate for applications to know that a CPU
> supports hotplug, but there is no convenient way to make the same
> determination in the kernel.
>
> To better model this relationship this patch introduces a new cpumask to
> track CPUs that support CPU hotplug operations.
>
> This new cpumask is populated at boot-time and remains static for the
> life of the machine. Bits set in the mask indicate a CPU which supports
> hotplug, but make no guarantees about whether that CPU is currently
> online or not. Likewise a cleared bit in the mask indicates either a
> CPU which cannot hotplug or a lack of a populated CPU.
>
> The purpose of this new cpumask is to aid kernel code which uses CPU to
> take CPUs online and offline. Possible uses are as a thermal event
> mitigation technique or as a power capping mechanism.
>
> Signed-off-by: Mike Turquette <mturquette@ti.com>
> ---
> include/linux/cpumask.h | 27 ++++++++++++++++++++++-----
> kernel/cpu.c | 18 ++++++++++++++++++
> 2 files changed, 40 insertions(+), 5 deletions(-)
>
> diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
> index b24ac56..9eed444 100644
> --- a/include/linux/cpumask.h
> +++ b/include/linux/cpumask.h
> @@ -39,10 +39,11 @@ extern int nr_cpu_ids;
> * The following particular system cpumasks and operations manage
> * possible, present, active and online cpus.
> *
> - * cpu_possible_mask- has bit 'cpu' set iff cpu is populatable
> - * cpu_present_mask - has bit 'cpu' set iff cpu is populated
> - * cpu_online_mask - has bit 'cpu' set iff cpu available to scheduler
> - * cpu_active_mask - has bit 'cpu' set iff cpu available to migration
> + * cpu_possible_mask - has bit 'cpu' set iff cpu is populatable
> + * cpu_hotpluggable_mask - has bit 'cpu' set iff cpu is hotpluggable
> + * cpu_present_mask - has bit 'cpu' set iff cpu is populated
> + * cpu_online_mask - has bit 'cpu' set iff cpu available to scheduler
> + * cpu_active_mask - has bit 'cpu' set iff cpu available to migration
> *
> * If !CONFIG_HOTPLUG_CPU, present == possible, and active == online.
> *
> @@ -51,7 +52,11 @@ extern int nr_cpu_ids;
> * life of that system boot. The cpu_present_mask is dynamic(*),
> * representing which CPUs are currently plugged in. And
> * cpu_online_mask is the dynamic subset of cpu_present_mask,
> - * indicating those CPUs available for scheduling.
> + * indicating those CPUs available for scheduling. The
> + * cpu_hotpluggable_mask is also fixed at boot time, as the set of CPU
> + * id's which are possible AND can hotplug. Cleared bits in this mask
> + * mean that either the CPU is not possible, or it is possible but does
> + * not support CPU hotplug operations.
> *
> * If HOTPLUG is enabled, then cpu_possible_mask is forced to have
> * all NR_CPUS bits set, otherwise it is just the set of CPUs that
> @@ -61,6 +66,9 @@ extern int nr_cpu_ids;
> * depending on what ACPI reports as currently plugged in, otherwise
> * cpu_present_mask is just a copy of cpu_possible_mask.
> *
> + * If CONFIG_HOTPLUG_CPU is enabled, then cpu_hotpluggable_mask matches
> + * the description above, otherwise it is the empty set.
> + *
> * (*) Well, cpu_present_mask is dynamic in the hotplug case. If not
> * hotplug, it's a copy of cpu_possible_mask, hence fixed at boot.
> *
> @@ -76,6 +84,7 @@ extern int nr_cpu_ids;
> */
>
> extern const struct cpumask *const cpu_possible_mask;
> +extern const struct cpumask *const cpu_hotpluggable_mask;
> extern const struct cpumask *const cpu_online_mask;
> extern const struct cpumask *const cpu_present_mask;
> extern const struct cpumask *const cpu_active_mask;
> @@ -85,19 +94,23 @@ extern const struct cpumask *const cpu_active_mask;
> #define num_possible_cpus() cpumask_weight(cpu_possible_mask)
> #define num_present_cpus() cpumask_weight(cpu_present_mask)
> #define num_active_cpus() cpumask_weight(cpu_active_mask)
> +#define num_hotpluggable_cpus() cpumask_weight(cpu_hotpluggable_mask)
> #define cpu_online(cpu) cpumask_test_cpu((cpu), cpu_online_mask)
> #define cpu_possible(cpu) cpumask_test_cpu((cpu), cpu_possible_mask)
> #define cpu_present(cpu) cpumask_test_cpu((cpu), cpu_present_mask)
> #define cpu_active(cpu) cpumask_test_cpu((cpu), cpu_active_mask)
> +#define cpu_hotpluggable(cpu) cpumask_test_cpu((cpu, cpu_hotpluggable_mask)
missing closing bracket? ^^^^
> #else
> #define num_online_cpus() 1U
> #define num_possible_cpus() 1U
> #define num_present_cpus() 1U
> #define num_active_cpus() 1U
> +#define num_hotpluggable_cpus() 0
> #define cpu_online(cpu) ((cpu) == 0)
> #define cpu_possible(cpu) ((cpu) == 0)
> #define cpu_present(cpu) ((cpu) == 0)
> #define cpu_active(cpu) ((cpu) == 0)
> +#define cpu_hotpluggable(cpu) 0
> #endif
>
> /* verify cpu argument to cpumask_* operators */
> @@ -678,16 +691,20 @@ extern const DECLARE_BITMAP(cpu_all_bits, NR_CPUS);
> #define cpu_none_mask to_cpumask(cpu_bit_bitmap[0])
>
> #define for_each_possible_cpu(cpu) for_each_cpu((cpu), cpu_possible_mask)
> +#define for_each_hotpluggable_cpu(cpu) \
> + for_each_cpu((cpu), cpu_hotpluggable_mask)
> #define for_each_online_cpu(cpu) for_each_cpu((cpu), cpu_online_mask)
> #define for_each_present_cpu(cpu) for_each_cpu((cpu), cpu_present_mask)
>
> /* Wrappers for arch boot code to manipulate normally-constant masks */
> void set_cpu_possible(unsigned int cpu, bool possible);
> +void set_cpu_hotpluggable(unsigned int cpu, bool hotpluggable);
> void set_cpu_present(unsigned int cpu, bool present);
> void set_cpu_online(unsigned int cpu, bool online);
> void set_cpu_active(unsigned int cpu, bool active);
> void init_cpu_present(const struct cpumask *src);
> void init_cpu_possible(const struct cpumask *src);
> +void init_cpu_hotpluggable(const struct cpumask *src);
> void init_cpu_online(const struct cpumask *src);
>
> /**
> diff --git a/kernel/cpu.c b/kernel/cpu.c
> index 12b7458..8c397c9 100644
> --- a/kernel/cpu.c
> +++ b/kernel/cpu.c
> @@ -536,6 +536,11 @@ static DECLARE_BITMAP(cpu_possible_bits, CONFIG_NR_CPUS) __read_mostly;
> const struct cpumask *const cpu_possible_mask = to_cpumask(cpu_possible_bits);
> EXPORT_SYMBOL(cpu_possible_mask);
>
> +static DECLARE_BITMAP(cpu_hotpluggable_bits, CONFIG_NR_CPUS) __read_mostly;
> +const struct cpumask *const cpu_hotpluggable_mask =
> + to_cpumask(cpu_hotpluggable_bits);
> +EXPORT_SYMBOL(cpu_hotpluggable_mask);
> +
> static DECLARE_BITMAP(cpu_online_bits, CONFIG_NR_CPUS) __read_mostly;
> const struct cpumask *const cpu_online_mask = to_cpumask(cpu_online_bits);
> EXPORT_SYMBOL(cpu_online_mask);
> @@ -556,6 +561,14 @@ void set_cpu_possible(unsigned int cpu, bool possible)
> cpumask_clear_cpu(cpu, to_cpumask(cpu_possible_bits));
> }
>
> +void set_cpu_hotpluggable(unsigned int cpu, bool hotpluggable)
> +{
> + if (hotpluggable)
> + cpumask_set_cpu(cpu, to_cpumask(cpu_hotpluggable_bits));
> + else
> + cpumask_clear_cpu(cpu, to_cpumask(cpu_hotpluggable_bits));
> +}
> +
> void set_cpu_present(unsigned int cpu, bool present)
> {
> if (present)
> @@ -590,6 +603,11 @@ void init_cpu_possible(const struct cpumask *src)
> cpumask_copy(to_cpumask(cpu_possible_bits), src);
> }
>
> +void init_cpu_hotpluggable(const struct cpumask *src)
> +{
> + cpumask_copy(to_cpumask(cpu_hotpluggable_bits), src);
> +}
> +
> void init_cpu_online(const struct cpumask *src)
> {
> cpumask_copy(to_cpumask(cpu_online_bits), src);
> --
> 1.7.4.1
>
>
> _______________________________________________
> linaro-dev mailing list
> linaro-dev@lists.linaro.org
> http://lists.linaro.org/mailman/listinfo/linaro-dev
^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [PATCH 1/2] cpumask: introduce cpumask for hotpluggable CPUs
2011-08-10 1:33 ` Mike Turquette
` (2 preceding siblings ...)
2011-08-10 8:42 ` Amit Kucheria
@ 2011-08-10 8:42 ` Amit Kucheria
2011-08-10 17:25 ` Turquette, Mike
2011-08-10 17:25 ` Turquette, Mike
3 siblings, 2 replies; 13+ messages in thread
From: Amit Kucheria @ 2011-08-10 8:42 UTC (permalink / raw)
To: Mike Turquette; +Cc: linux-kernel, linux-pm, linaro-dev, patches
On 11 Aug 09, Mike Turquette wrote:
> On some platforms it is possible to have some CPUs which support CPU
> hotplug and some which do not. Currently the prescence of an 'online'
> sysfs entry in userspace is adequate for applications to know that a CPU
> supports hotplug, but there is no convenient way to make the same
> determination in the kernel.
>
> To better model this relationship this patch introduces a new cpumask to
> track CPUs that support CPU hotplug operations.
>
> This new cpumask is populated at boot-time and remains static for the
> life of the machine. Bits set in the mask indicate a CPU which supports
> hotplug, but make no guarantees about whether that CPU is currently
> online or not. Likewise a cleared bit in the mask indicates either a
> CPU which cannot hotplug or a lack of a populated CPU.
>
> The purpose of this new cpumask is to aid kernel code which uses CPU to
> take CPUs online and offline. Possible uses are as a thermal event
> mitigation technique or as a power capping mechanism.
>
> Signed-off-by: Mike Turquette <mturquette@ti.com>
> ---
> include/linux/cpumask.h | 27 ++++++++++++++++++++++-----
> kernel/cpu.c | 18 ++++++++++++++++++
> 2 files changed, 40 insertions(+), 5 deletions(-)
>
> diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
> index b24ac56..9eed444 100644
> --- a/include/linux/cpumask.h
> +++ b/include/linux/cpumask.h
> @@ -39,10 +39,11 @@ extern int nr_cpu_ids;
> * The following particular system cpumasks and operations manage
> * possible, present, active and online cpus.
> *
> - * cpu_possible_mask- has bit 'cpu' set iff cpu is populatable
> - * cpu_present_mask - has bit 'cpu' set iff cpu is populated
> - * cpu_online_mask - has bit 'cpu' set iff cpu available to scheduler
> - * cpu_active_mask - has bit 'cpu' set iff cpu available to migration
> + * cpu_possible_mask - has bit 'cpu' set iff cpu is populatable
> + * cpu_hotpluggable_mask - has bit 'cpu' set iff cpu is hotpluggable
> + * cpu_present_mask - has bit 'cpu' set iff cpu is populated
> + * cpu_online_mask - has bit 'cpu' set iff cpu available to scheduler
> + * cpu_active_mask - has bit 'cpu' set iff cpu available to migration
> *
> * If !CONFIG_HOTPLUG_CPU, present == possible, and active == online.
> *
> @@ -51,7 +52,11 @@ extern int nr_cpu_ids;
> * life of that system boot. The cpu_present_mask is dynamic(*),
> * representing which CPUs are currently plugged in. And
> * cpu_online_mask is the dynamic subset of cpu_present_mask,
> - * indicating those CPUs available for scheduling.
> + * indicating those CPUs available for scheduling. The
> + * cpu_hotpluggable_mask is also fixed at boot time, as the set of CPU
> + * id's which are possible AND can hotplug. Cleared bits in this mask
> + * mean that either the CPU is not possible, or it is possible but does
> + * not support CPU hotplug operations.
> *
> * If HOTPLUG is enabled, then cpu_possible_mask is forced to have
> * all NR_CPUS bits set, otherwise it is just the set of CPUs that
> @@ -61,6 +66,9 @@ extern int nr_cpu_ids;
> * depending on what ACPI reports as currently plugged in, otherwise
> * cpu_present_mask is just a copy of cpu_possible_mask.
> *
> + * If CONFIG_HOTPLUG_CPU is enabled, then cpu_hotpluggable_mask matches
> + * the description above, otherwise it is the empty set.
> + *
> * (*) Well, cpu_present_mask is dynamic in the hotplug case. If not
> * hotplug, it's a copy of cpu_possible_mask, hence fixed at boot.
> *
> @@ -76,6 +84,7 @@ extern int nr_cpu_ids;
> */
>
> extern const struct cpumask *const cpu_possible_mask;
> +extern const struct cpumask *const cpu_hotpluggable_mask;
> extern const struct cpumask *const cpu_online_mask;
> extern const struct cpumask *const cpu_present_mask;
> extern const struct cpumask *const cpu_active_mask;
> @@ -85,19 +94,23 @@ extern const struct cpumask *const cpu_active_mask;
> #define num_possible_cpus() cpumask_weight(cpu_possible_mask)
> #define num_present_cpus() cpumask_weight(cpu_present_mask)
> #define num_active_cpus() cpumask_weight(cpu_active_mask)
> +#define num_hotpluggable_cpus() cpumask_weight(cpu_hotpluggable_mask)
> #define cpu_online(cpu) cpumask_test_cpu((cpu), cpu_online_mask)
> #define cpu_possible(cpu) cpumask_test_cpu((cpu), cpu_possible_mask)
> #define cpu_present(cpu) cpumask_test_cpu((cpu), cpu_present_mask)
> #define cpu_active(cpu) cpumask_test_cpu((cpu), cpu_active_mask)
> +#define cpu_hotpluggable(cpu) cpumask_test_cpu((cpu, cpu_hotpluggable_mask)
missing closing bracket? ^^^^
> #else
> #define num_online_cpus() 1U
> #define num_possible_cpus() 1U
> #define num_present_cpus() 1U
> #define num_active_cpus() 1U
> +#define num_hotpluggable_cpus() 0
> #define cpu_online(cpu) ((cpu) == 0)
> #define cpu_possible(cpu) ((cpu) == 0)
> #define cpu_present(cpu) ((cpu) == 0)
> #define cpu_active(cpu) ((cpu) == 0)
> +#define cpu_hotpluggable(cpu) 0
> #endif
>
> /* verify cpu argument to cpumask_* operators */
> @@ -678,16 +691,20 @@ extern const DECLARE_BITMAP(cpu_all_bits, NR_CPUS);
> #define cpu_none_mask to_cpumask(cpu_bit_bitmap[0])
>
> #define for_each_possible_cpu(cpu) for_each_cpu((cpu), cpu_possible_mask)
> +#define for_each_hotpluggable_cpu(cpu) \
> + for_each_cpu((cpu), cpu_hotpluggable_mask)
> #define for_each_online_cpu(cpu) for_each_cpu((cpu), cpu_online_mask)
> #define for_each_present_cpu(cpu) for_each_cpu((cpu), cpu_present_mask)
>
> /* Wrappers for arch boot code to manipulate normally-constant masks */
> void set_cpu_possible(unsigned int cpu, bool possible);
> +void set_cpu_hotpluggable(unsigned int cpu, bool hotpluggable);
> void set_cpu_present(unsigned int cpu, bool present);
> void set_cpu_online(unsigned int cpu, bool online);
> void set_cpu_active(unsigned int cpu, bool active);
> void init_cpu_present(const struct cpumask *src);
> void init_cpu_possible(const struct cpumask *src);
> +void init_cpu_hotpluggable(const struct cpumask *src);
> void init_cpu_online(const struct cpumask *src);
>
> /**
> diff --git a/kernel/cpu.c b/kernel/cpu.c
> index 12b7458..8c397c9 100644
> --- a/kernel/cpu.c
> +++ b/kernel/cpu.c
> @@ -536,6 +536,11 @@ static DECLARE_BITMAP(cpu_possible_bits, CONFIG_NR_CPUS) __read_mostly;
> const struct cpumask *const cpu_possible_mask = to_cpumask(cpu_possible_bits);
> EXPORT_SYMBOL(cpu_possible_mask);
>
> +static DECLARE_BITMAP(cpu_hotpluggable_bits, CONFIG_NR_CPUS) __read_mostly;
> +const struct cpumask *const cpu_hotpluggable_mask =
> + to_cpumask(cpu_hotpluggable_bits);
> +EXPORT_SYMBOL(cpu_hotpluggable_mask);
> +
> static DECLARE_BITMAP(cpu_online_bits, CONFIG_NR_CPUS) __read_mostly;
> const struct cpumask *const cpu_online_mask = to_cpumask(cpu_online_bits);
> EXPORT_SYMBOL(cpu_online_mask);
> @@ -556,6 +561,14 @@ void set_cpu_possible(unsigned int cpu, bool possible)
> cpumask_clear_cpu(cpu, to_cpumask(cpu_possible_bits));
> }
>
> +void set_cpu_hotpluggable(unsigned int cpu, bool hotpluggable)
> +{
> + if (hotpluggable)
> + cpumask_set_cpu(cpu, to_cpumask(cpu_hotpluggable_bits));
> + else
> + cpumask_clear_cpu(cpu, to_cpumask(cpu_hotpluggable_bits));
> +}
> +
> void set_cpu_present(unsigned int cpu, bool present)
> {
> if (present)
> @@ -590,6 +603,11 @@ void init_cpu_possible(const struct cpumask *src)
> cpumask_copy(to_cpumask(cpu_possible_bits), src);
> }
>
> +void init_cpu_hotpluggable(const struct cpumask *src)
> +{
> + cpumask_copy(to_cpumask(cpu_hotpluggable_bits), src);
> +}
> +
> void init_cpu_online(const struct cpumask *src)
> {
> cpumask_copy(to_cpumask(cpu_online_bits), src);
> --
> 1.7.4.1
>
>
> _______________________________________________
> linaro-dev mailing list
> linaro-dev@lists.linaro.org
> http://lists.linaro.org/mailman/listinfo/linaro-dev
^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [PATCH 1/2] cpumask: introduce cpumask for hotpluggable CPUs
2011-08-10 8:42 ` Amit Kucheria
@ 2011-08-10 17:25 ` Turquette, Mike
2011-08-10 17:25 ` Turquette, Mike
1 sibling, 0 replies; 13+ messages in thread
From: Turquette, Mike @ 2011-08-10 17:25 UTC (permalink / raw)
To: Mike Turquette, linux-kernel, linux-pm, linaro-dev, patches
On Wed, Aug 10, 2011 at 1:42 AM, Amit Kucheria <amit.kucheria@linaro.org> wrote:
> On 11 Aug 09, Mike Turquette wrote:
>> On some platforms it is possible to have some CPUs which support CPU
>> hotplug and some which do not. Currently the prescence of an 'online'
>> sysfs entry in userspace is adequate for applications to know that a CPU
>> supports hotplug, but there is no convenient way to make the same
>> determination in the kernel.
>>
>> To better model this relationship this patch introduces a new cpumask to
>> track CPUs that support CPU hotplug operations.
>>
>> This new cpumask is populated at boot-time and remains static for the
>> life of the machine. Bits set in the mask indicate a CPU which supports
>> hotplug, but make no guarantees about whether that CPU is currently
>> online or not. Likewise a cleared bit in the mask indicates either a
>> CPU which cannot hotplug or a lack of a populated CPU.
>>
>> The purpose of this new cpumask is to aid kernel code which uses CPU to
>> take CPUs online and offline. Possible uses are as a thermal event
>> mitigation technique or as a power capping mechanism.
>>
>> Signed-off-by: Mike Turquette <mturquette@ti.com>
>> ---
>> include/linux/cpumask.h | 27 ++++++++++++++++++++++-----
>> kernel/cpu.c | 18 ++++++++++++++++++
>> 2 files changed, 40 insertions(+), 5 deletions(-)
>>
>> diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
>> index b24ac56..9eed444 100644
>> --- a/include/linux/cpumask.h
>> +++ b/include/linux/cpumask.h
>> @@ -39,10 +39,11 @@ extern int nr_cpu_ids;
>> * The following particular system cpumasks and operations manage
>> * possible, present, active and online cpus.
>> *
>> - * cpu_possible_mask- has bit 'cpu' set iff cpu is populatable
>> - * cpu_present_mask - has bit 'cpu' set iff cpu is populated
>> - * cpu_online_mask - has bit 'cpu' set iff cpu available to scheduler
>> - * cpu_active_mask - has bit 'cpu' set iff cpu available to migration
>> + * cpu_possible_mask - has bit 'cpu' set iff cpu is populatable
>> + * cpu_hotpluggable_mask - has bit 'cpu' set iff cpu is hotpluggable
>> + * cpu_present_mask - has bit 'cpu' set iff cpu is populated
>> + * cpu_online_mask - has bit 'cpu' set iff cpu available to scheduler
>> + * cpu_active_mask - has bit 'cpu' set iff cpu available to migration
>> *
>> * If !CONFIG_HOTPLUG_CPU, present == possible, and active == online.
>> *
>> @@ -51,7 +52,11 @@ extern int nr_cpu_ids;
>> * life of that system boot. The cpu_present_mask is dynamic(*),
>> * representing which CPUs are currently plugged in. And
>> * cpu_online_mask is the dynamic subset of cpu_present_mask,
>> - * indicating those CPUs available for scheduling.
>> + * indicating those CPUs available for scheduling. The
>> + * cpu_hotpluggable_mask is also fixed at boot time, as the set of CPU
>> + * id's which are possible AND can hotplug. Cleared bits in this mask
>> + * mean that either the CPU is not possible, or it is possible but does
>> + * not support CPU hotplug operations.
>> *
>> * If HOTPLUG is enabled, then cpu_possible_mask is forced to have
>> * all NR_CPUS bits set, otherwise it is just the set of CPUs that
>> @@ -61,6 +66,9 @@ extern int nr_cpu_ids;
>> * depending on what ACPI reports as currently plugged in, otherwise
>> * cpu_present_mask is just a copy of cpu_possible_mask.
>> *
>> + * If CONFIG_HOTPLUG_CPU is enabled, then cpu_hotpluggable_mask matches
>> + * the description above, otherwise it is the empty set.
>> + *
>> * (*) Well, cpu_present_mask is dynamic in the hotplug case. If not
>> * hotplug, it's a copy of cpu_possible_mask, hence fixed at boot.
>> *
>> @@ -76,6 +84,7 @@ extern int nr_cpu_ids;
>> */
>>
>> extern const struct cpumask *const cpu_possible_mask;
>> +extern const struct cpumask *const cpu_hotpluggable_mask;
>> extern const struct cpumask *const cpu_online_mask;
>> extern const struct cpumask *const cpu_present_mask;
>> extern const struct cpumask *const cpu_active_mask;
>> @@ -85,19 +94,23 @@ extern const struct cpumask *const cpu_active_mask;
>> #define num_possible_cpus() cpumask_weight(cpu_possible_mask)
>> #define num_present_cpus() cpumask_weight(cpu_present_mask)
>> #define num_active_cpus() cpumask_weight(cpu_active_mask)
>> +#define num_hotpluggable_cpus() cpumask_weight(cpu_hotpluggable_mask)
>> #define cpu_online(cpu) cpumask_test_cpu((cpu), cpu_online_mask)
>> #define cpu_possible(cpu) cpumask_test_cpu((cpu), cpu_possible_mask)
>> #define cpu_present(cpu) cpumask_test_cpu((cpu), cpu_present_mask)
>> #define cpu_active(cpu) cpumask_test_cpu((cpu), cpu_active_mask)
>> +#define cpu_hotpluggable(cpu) cpumask_test_cpu((cpu, cpu_hotpluggable_mask)
>
> missing closing bracket? ^^^^
Oops. Will fix in V2.
Thanks,
Mike
>> #else
>> #define num_online_cpus() 1U
>> #define num_possible_cpus() 1U
>> #define num_present_cpus() 1U
>> #define num_active_cpus() 1U
>> +#define num_hotpluggable_cpus() 0
>> #define cpu_online(cpu) ((cpu) == 0)
>> #define cpu_possible(cpu) ((cpu) == 0)
>> #define cpu_present(cpu) ((cpu) == 0)
>> #define cpu_active(cpu) ((cpu) == 0)
>> +#define cpu_hotpluggable(cpu) 0
>> #endif
>>
>> /* verify cpu argument to cpumask_* operators */
>> @@ -678,16 +691,20 @@ extern const DECLARE_BITMAP(cpu_all_bits, NR_CPUS);
>> #define cpu_none_mask to_cpumask(cpu_bit_bitmap[0])
>>
>> #define for_each_possible_cpu(cpu) for_each_cpu((cpu), cpu_possible_mask)
>> +#define for_each_hotpluggable_cpu(cpu) \
>> + for_each_cpu((cpu), cpu_hotpluggable_mask)
>> #define for_each_online_cpu(cpu) for_each_cpu((cpu), cpu_online_mask)
>> #define for_each_present_cpu(cpu) for_each_cpu((cpu), cpu_present_mask)
>>
>> /* Wrappers for arch boot code to manipulate normally-constant masks */
>> void set_cpu_possible(unsigned int cpu, bool possible);
>> +void set_cpu_hotpluggable(unsigned int cpu, bool hotpluggable);
>> void set_cpu_present(unsigned int cpu, bool present);
>> void set_cpu_online(unsigned int cpu, bool online);
>> void set_cpu_active(unsigned int cpu, bool active);
>> void init_cpu_present(const struct cpumask *src);
>> void init_cpu_possible(const struct cpumask *src);
>> +void init_cpu_hotpluggable(const struct cpumask *src);
>> void init_cpu_online(const struct cpumask *src);
>>
>> /**
>> diff --git a/kernel/cpu.c b/kernel/cpu.c
>> index 12b7458..8c397c9 100644
>> --- a/kernel/cpu.c
>> +++ b/kernel/cpu.c
>> @@ -536,6 +536,11 @@ static DECLARE_BITMAP(cpu_possible_bits, CONFIG_NR_CPUS) __read_mostly;
>> const struct cpumask *const cpu_possible_mask = to_cpumask(cpu_possible_bits);
>> EXPORT_SYMBOL(cpu_possible_mask);
>>
>> +static DECLARE_BITMAP(cpu_hotpluggable_bits, CONFIG_NR_CPUS) __read_mostly;
>> +const struct cpumask *const cpu_hotpluggable_mask =
>> + to_cpumask(cpu_hotpluggable_bits);
>> +EXPORT_SYMBOL(cpu_hotpluggable_mask);
>> +
>> static DECLARE_BITMAP(cpu_online_bits, CONFIG_NR_CPUS) __read_mostly;
>> const struct cpumask *const cpu_online_mask = to_cpumask(cpu_online_bits);
>> EXPORT_SYMBOL(cpu_online_mask);
>> @@ -556,6 +561,14 @@ void set_cpu_possible(unsigned int cpu, bool possible)
>> cpumask_clear_cpu(cpu, to_cpumask(cpu_possible_bits));
>> }
>>
>> +void set_cpu_hotpluggable(unsigned int cpu, bool hotpluggable)
>> +{
>> + if (hotpluggable)
>> + cpumask_set_cpu(cpu, to_cpumask(cpu_hotpluggable_bits));
>> + else
>> + cpumask_clear_cpu(cpu, to_cpumask(cpu_hotpluggable_bits));
>> +}
>> +
>> void set_cpu_present(unsigned int cpu, bool present)
>> {
>> if (present)
>> @@ -590,6 +603,11 @@ void init_cpu_possible(const struct cpumask *src)
>> cpumask_copy(to_cpumask(cpu_possible_bits), src);
>> }
>>
>> +void init_cpu_hotpluggable(const struct cpumask *src)
>> +{
>> + cpumask_copy(to_cpumask(cpu_hotpluggable_bits), src);
>> +}
>> +
>> void init_cpu_online(const struct cpumask *src)
>> {
>> cpumask_copy(to_cpumask(cpu_online_bits), src);
>> --
>> 1.7.4.1
>>
>>
>> _______________________________________________
>> linaro-dev mailing list
>> linaro-dev@lists.linaro.org
>> http://lists.linaro.org/mailman/listinfo/linaro-dev
>
^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [PATCH 1/2] cpumask: introduce cpumask for hotpluggable CPUs
2011-08-10 8:42 ` Amit Kucheria
2011-08-10 17:25 ` Turquette, Mike
@ 2011-08-10 17:25 ` Turquette, Mike
1 sibling, 0 replies; 13+ messages in thread
From: Turquette, Mike @ 2011-08-10 17:25 UTC (permalink / raw)
To: Mike Turquette, linux-kernel, linux-pm, linaro-dev, patches
On Wed, Aug 10, 2011 at 1:42 AM, Amit Kucheria <amit.kucheria@linaro.org> wrote:
> On 11 Aug 09, Mike Turquette wrote:
>> On some platforms it is possible to have some CPUs which support CPU
>> hotplug and some which do not. Currently the prescence of an 'online'
>> sysfs entry in userspace is adequate for applications to know that a CPU
>> supports hotplug, but there is no convenient way to make the same
>> determination in the kernel.
>>
>> To better model this relationship this patch introduces a new cpumask to
>> track CPUs that support CPU hotplug operations.
>>
>> This new cpumask is populated at boot-time and remains static for the
>> life of the machine. Bits set in the mask indicate a CPU which supports
>> hotplug, but make no guarantees about whether that CPU is currently
>> online or not. Likewise a cleared bit in the mask indicates either a
>> CPU which cannot hotplug or a lack of a populated CPU.
>>
>> The purpose of this new cpumask is to aid kernel code which uses CPU to
>> take CPUs online and offline. Possible uses are as a thermal event
>> mitigation technique or as a power capping mechanism.
>>
>> Signed-off-by: Mike Turquette <mturquette@ti.com>
>> ---
>> include/linux/cpumask.h | 27 ++++++++++++++++++++++-----
>> kernel/cpu.c | 18 ++++++++++++++++++
>> 2 files changed, 40 insertions(+), 5 deletions(-)
>>
>> diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
>> index b24ac56..9eed444 100644
>> --- a/include/linux/cpumask.h
>> +++ b/include/linux/cpumask.h
>> @@ -39,10 +39,11 @@ extern int nr_cpu_ids;
>> * The following particular system cpumasks and operations manage
>> * possible, present, active and online cpus.
>> *
>> - * cpu_possible_mask- has bit 'cpu' set iff cpu is populatable
>> - * cpu_present_mask - has bit 'cpu' set iff cpu is populated
>> - * cpu_online_mask - has bit 'cpu' set iff cpu available to scheduler
>> - * cpu_active_mask - has bit 'cpu' set iff cpu available to migration
>> + * cpu_possible_mask - has bit 'cpu' set iff cpu is populatable
>> + * cpu_hotpluggable_mask - has bit 'cpu' set iff cpu is hotpluggable
>> + * cpu_present_mask - has bit 'cpu' set iff cpu is populated
>> + * cpu_online_mask - has bit 'cpu' set iff cpu available to scheduler
>> + * cpu_active_mask - has bit 'cpu' set iff cpu available to migration
>> *
>> * If !CONFIG_HOTPLUG_CPU, present == possible, and active == online.
>> *
>> @@ -51,7 +52,11 @@ extern int nr_cpu_ids;
>> * life of that system boot. The cpu_present_mask is dynamic(*),
>> * representing which CPUs are currently plugged in. And
>> * cpu_online_mask is the dynamic subset of cpu_present_mask,
>> - * indicating those CPUs available for scheduling.
>> + * indicating those CPUs available for scheduling. The
>> + * cpu_hotpluggable_mask is also fixed at boot time, as the set of CPU
>> + * id's which are possible AND can hotplug. Cleared bits in this mask
>> + * mean that either the CPU is not possible, or it is possible but does
>> + * not support CPU hotplug operations.
>> *
>> * If HOTPLUG is enabled, then cpu_possible_mask is forced to have
>> * all NR_CPUS bits set, otherwise it is just the set of CPUs that
>> @@ -61,6 +66,9 @@ extern int nr_cpu_ids;
>> * depending on what ACPI reports as currently plugged in, otherwise
>> * cpu_present_mask is just a copy of cpu_possible_mask.
>> *
>> + * If CONFIG_HOTPLUG_CPU is enabled, then cpu_hotpluggable_mask matches
>> + * the description above, otherwise it is the empty set.
>> + *
>> * (*) Well, cpu_present_mask is dynamic in the hotplug case. If not
>> * hotplug, it's a copy of cpu_possible_mask, hence fixed at boot.
>> *
>> @@ -76,6 +84,7 @@ extern int nr_cpu_ids;
>> */
>>
>> extern const struct cpumask *const cpu_possible_mask;
>> +extern const struct cpumask *const cpu_hotpluggable_mask;
>> extern const struct cpumask *const cpu_online_mask;
>> extern const struct cpumask *const cpu_present_mask;
>> extern const struct cpumask *const cpu_active_mask;
>> @@ -85,19 +94,23 @@ extern const struct cpumask *const cpu_active_mask;
>> #define num_possible_cpus() cpumask_weight(cpu_possible_mask)
>> #define num_present_cpus() cpumask_weight(cpu_present_mask)
>> #define num_active_cpus() cpumask_weight(cpu_active_mask)
>> +#define num_hotpluggable_cpus() cpumask_weight(cpu_hotpluggable_mask)
>> #define cpu_online(cpu) cpumask_test_cpu((cpu), cpu_online_mask)
>> #define cpu_possible(cpu) cpumask_test_cpu((cpu), cpu_possible_mask)
>> #define cpu_present(cpu) cpumask_test_cpu((cpu), cpu_present_mask)
>> #define cpu_active(cpu) cpumask_test_cpu((cpu), cpu_active_mask)
>> +#define cpu_hotpluggable(cpu) cpumask_test_cpu((cpu, cpu_hotpluggable_mask)
>
> missing closing bracket? ^^^^
Oops. Will fix in V2.
Thanks,
Mike
>> #else
>> #define num_online_cpus() 1U
>> #define num_possible_cpus() 1U
>> #define num_present_cpus() 1U
>> #define num_active_cpus() 1U
>> +#define num_hotpluggable_cpus() 0
>> #define cpu_online(cpu) ((cpu) == 0)
>> #define cpu_possible(cpu) ((cpu) == 0)
>> #define cpu_present(cpu) ((cpu) == 0)
>> #define cpu_active(cpu) ((cpu) == 0)
>> +#define cpu_hotpluggable(cpu) 0
>> #endif
>>
>> /* verify cpu argument to cpumask_* operators */
>> @@ -678,16 +691,20 @@ extern const DECLARE_BITMAP(cpu_all_bits, NR_CPUS);
>> #define cpu_none_mask to_cpumask(cpu_bit_bitmap[0])
>>
>> #define for_each_possible_cpu(cpu) for_each_cpu((cpu), cpu_possible_mask)
>> +#define for_each_hotpluggable_cpu(cpu) \
>> + for_each_cpu((cpu), cpu_hotpluggable_mask)
>> #define for_each_online_cpu(cpu) for_each_cpu((cpu), cpu_online_mask)
>> #define for_each_present_cpu(cpu) for_each_cpu((cpu), cpu_present_mask)
>>
>> /* Wrappers for arch boot code to manipulate normally-constant masks */
>> void set_cpu_possible(unsigned int cpu, bool possible);
>> +void set_cpu_hotpluggable(unsigned int cpu, bool hotpluggable);
>> void set_cpu_present(unsigned int cpu, bool present);
>> void set_cpu_online(unsigned int cpu, bool online);
>> void set_cpu_active(unsigned int cpu, bool active);
>> void init_cpu_present(const struct cpumask *src);
>> void init_cpu_possible(const struct cpumask *src);
>> +void init_cpu_hotpluggable(const struct cpumask *src);
>> void init_cpu_online(const struct cpumask *src);
>>
>> /**
>> diff --git a/kernel/cpu.c b/kernel/cpu.c
>> index 12b7458..8c397c9 100644
>> --- a/kernel/cpu.c
>> +++ b/kernel/cpu.c
>> @@ -536,6 +536,11 @@ static DECLARE_BITMAP(cpu_possible_bits, CONFIG_NR_CPUS) __read_mostly;
>> const struct cpumask *const cpu_possible_mask = to_cpumask(cpu_possible_bits);
>> EXPORT_SYMBOL(cpu_possible_mask);
>>
>> +static DECLARE_BITMAP(cpu_hotpluggable_bits, CONFIG_NR_CPUS) __read_mostly;
>> +const struct cpumask *const cpu_hotpluggable_mask =
>> + to_cpumask(cpu_hotpluggable_bits);
>> +EXPORT_SYMBOL(cpu_hotpluggable_mask);
>> +
>> static DECLARE_BITMAP(cpu_online_bits, CONFIG_NR_CPUS) __read_mostly;
>> const struct cpumask *const cpu_online_mask = to_cpumask(cpu_online_bits);
>> EXPORT_SYMBOL(cpu_online_mask);
>> @@ -556,6 +561,14 @@ void set_cpu_possible(unsigned int cpu, bool possible)
>> cpumask_clear_cpu(cpu, to_cpumask(cpu_possible_bits));
>> }
>>
>> +void set_cpu_hotpluggable(unsigned int cpu, bool hotpluggable)
>> +{
>> + if (hotpluggable)
>> + cpumask_set_cpu(cpu, to_cpumask(cpu_hotpluggable_bits));
>> + else
>> + cpumask_clear_cpu(cpu, to_cpumask(cpu_hotpluggable_bits));
>> +}
>> +
>> void set_cpu_present(unsigned int cpu, bool present)
>> {
>> if (present)
>> @@ -590,6 +603,11 @@ void init_cpu_possible(const struct cpumask *src)
>> cpumask_copy(to_cpumask(cpu_possible_bits), src);
>> }
>>
>> +void init_cpu_hotpluggable(const struct cpumask *src)
>> +{
>> + cpumask_copy(to_cpumask(cpu_hotpluggable_bits), src);
>> +}
>> +
>> void init_cpu_online(const struct cpumask *src)
>> {
>> cpumask_copy(to_cpumask(cpu_online_bits), src);
>> --
>> 1.7.4.1
>>
>>
>> _______________________________________________
>> linaro-dev mailing list
>> linaro-dev@lists.linaro.org
>> http://lists.linaro.org/mailman/listinfo/linaro-dev
>
^ permalink raw reply [flat|nested] 13+ messages in thread
end of thread, other threads:[~2011-08-10 17:38 UTC | newest]
Thread overview: 13+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2011-08-10 1:33 [PATCH 0/2] new cpumask for hotpluggable CPUs Mike Turquette
2011-08-10 1:33 ` [PATCH 1/2] cpumask: introduce " Mike Turquette
2011-08-10 1:33 ` Mike Turquette
2011-08-10 2:01 ` Christian Robottom Reis
2011-08-10 2:01 ` Christian Robottom Reis
2011-08-10 2:03 ` Turquette, Mike
2011-08-10 2:03 ` Turquette, Mike
2011-08-10 8:42 ` Amit Kucheria
2011-08-10 8:42 ` Amit Kucheria
2011-08-10 17:25 ` Turquette, Mike
2011-08-10 17:25 ` Turquette, Mike
2011-08-10 1:33 ` [PATCH 2/2] cpu: update cpu_hotpluggable_mask in register_cpu Mike Turquette
2011-08-10 1:33 ` Mike Turquette
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