linux-kernel - [PATCH v2 0/2] cpu: pseries: Offline state framework.

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Date:	Fri, 28 Aug 2009 15:30:11 +0530
From:	Gautham R Shenoy <ego@...ibm.com>
To:	Joel Schopp <jschopp@...tin.ibm.com>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Vaidyanathan Srinivasan <svaidy@...ux.vnet.ibm.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Dipankar Sarma <dipankar@...ibm.com>
Cc:	Balbir Singh <balbir@...ibm.com>,
	Venkatesh Pallipadi <venkatesh.pallipadi@...el.com>,
	linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
	"Darrick J. Wong" <djwong@...ibm.com>
Subject: [PATCH v2 0/2] cpu: pseries: Offline state framework.

Hi,

This is the version 2 of the patch series to provide a cpu-offline framework
that enables the administrators choose the state the offline CPU must be put
into when multiple such states are exposed by the underlying architecture.

Version 1 of the Patch can be found here:
http://lkml.org/lkml/2009/8/6/236

The patch-series exposes the following sysfs tunables to
allow the system-adminstrator to choose the state of a CPU:

To query the available hotplug states, one needs to read the sysfs tunable:
	/sys/devices/system/cpu/cpu<number>/available_hotplug_states
To query or set the current state, on needs to read/write the sysfs tunable:
	/sys/devices/system/cpu/cpu<number>/current_states

The patchset ensures that the writes to the "current_state" sysfs file are
serialized against the writes to the "online" file.

This patchset also contains the offline state driver implemented for
pSeries. For pSeries, we define three available_hotplug_states. They are:

	online: The processor is online.

	deallocate: This is the the default behaviour when the cpu is offlined
	even in the absense of this driver. The CPU would call make an
	rtas_stop_self() call and hand over the CPU back to the resource pool,
	thereby effectively deallocating that vCPU from the LPAR.
	NOTE: This would result in a configuration change to the LPAR
	which is visible to the outside world.

	deactivate: This cedes the vCPU to the hypervisor which
	in turn can put the vCPU time to the best use.
	NOTE: This option DOES NOT result in a configuration change
	and the vCPU would be still entitled to the LPAR to which it earlier
	belong to.

Awaiting your feedback.
---

Gautham R Shenoy (2):
      cpu: Implement cpu-offline-state driver for pSeries.
      cpu: Offline state Framework.


 arch/powerpc/platforms/pseries/Makefile         |    2 
 arch/powerpc/platforms/pseries/hotplug-cpu.c    |   76 +++++++++-
 arch/powerpc/platforms/pseries/offline_driver.c |  161 +++++++++++++++++++++
 arch/powerpc/platforms/pseries/offline_driver.h |   20 +++
 arch/powerpc/platforms/pseries/smp.c            |   17 ++
 drivers/base/cpu.c                              |  176 ++++++++++++++++++++++-
 include/linux/cpu.h                             |   30 ++++
 7 files changed, 465 insertions(+), 17 deletions(-)
 create mode 100644 arch/powerpc/platforms/pseries/offline_driver.c
 create mode 100644 arch/powerpc/platforms/pseries/offline_driver.h

-- 
Thanks and Regards
gautham.
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