Re: [PATCH v3 2/3] cpu: Offline state Framework.

Randy Dunlap
2009-09-30T17:32:23Z

On Tue, 15 Sep 2009 17:37:06 +0530 Gautham R Shenoy wrote:

> Signed-off-by: Gautham R Shenoy <ego@in.ibm.com>
> ---
> Documentation/cpu-hotplug.txt | 22 +++++
> drivers/base/cpu.c | 181 +++++++++++++++++++++++++++++++++++++++--
> include/linux/cpu.h | 10 ++
> 3 files changed, 204 insertions(+), 9 deletions(-)
>
> diff --git a/Documentation/cpu-hotplug.txt b/Documentation/cpu-hotplug.txt
> index 9d620c1..dcec06d 100644
> --- a/Documentation/cpu-hotplug.txt
> +++ b/Documentation/cpu-hotplug.txt
> @@ -115,6 +115,28 @@ Just remember the critical section cannot call any
> function that can sleep or schedule this process away. The preempt_disable()
> will work as long as stop_machine_run() is used to take a cpu down.
>
> +CPU-offline states
> +--------------------------------------
> +On architectures which allow the more than one valid state when

^drop "the"

> +the CPU goes offline, the system administrator can decide
> +the state the CPU needs to go to when it is offlined.

s/needs to/should/

> +
> +If the architecture has implemented a cpu-offline driver exposing these
> +multiple offline states, the system administrator can use the following sysfs
> +interfaces to query the available hotplug states and also query and set the
> +current hotplug state for a given cpu:
> +
> +To query the hotplug states, on needs to perform a read on:

one

> +/sys/devices/system/cpu/cpu<number>/available_hotplug_states
> +
> +To query or set the current state for a particular CPU,
> +one needs to use the sysfs interface
> +
> +/sys/devices/system/cpu/cpu<number>/current_hotplug_state
> +
> +Writes to the "online" sysfs files are serialized against the writes to the
> +"current_hotplug_state" file.
> +
> CPU Hotplug - Frequently Asked Questions.
>
> Q: How to enable my kernel to support CPU hotplug?

---
~Randy