Commit Graph

29 Commits

Author SHA1 Message Date
Rusty Russell
270bd400e8 cpumask: fix cpu-hotplug documentation
It refers to an obsolete function.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-doc@vger.kernel.org
2015-03-05 13:37:01 +10:30
Srivatsa S. Bhat
8489d90b5f Doc/cpu-hotplug: Specify race-free way to register CPU hotplug callbacks
Recommend the usage of the new CPU hotplug callback registration APIs
(__register_cpu_notifier() etc), when subsystems need to also perform
initialization for already online CPUs. Provide examples of correct
and race-free ways of achieving this, and point out the kinds of code
that are error-prone.

Cc: Rob Landley <rob@landley.net>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2014-03-20 13:43:40 +01:00
Sangjung Woo
f3c73a99a1 Documentation/cpu-hotplug.txt: fix a typo in example code
As the notifier_block name (i.e.  foobar_cpu_notifer) is different from
the parameter (i.e.foobar_cpu_notifier) of register function, that is
definitely error and it also makes readers confused.

Signed-off-by: Sangjung Woo <sangjung.woo@samsung.com>
Reviewed-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-01-23 16:37:01 -08:00
Jean Delvare
b300645aec MAINTAINERS: update Zwane Mwaikambo's e-mail address
Zwane Mwaikambo's @arm.linux.org.uk address no longer works.  In February
2013 he asked for his gmail address to be used instead [1] so let's just
do that.

[1] http://marc.info/?l=linux-kernel&m=136079068903214&w=2

Signed-off-by: Jean Delvare <jdelvare@suse.de>
Cc: Russell King <rmk+kernel@arm.linux.org.uk>
Cc: Zwane Mwaikambo <zwanem@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-11-13 12:09:14 +09:00
Paul Gortmaker
0db0628d90 kernel: delete __cpuinit usage from all core kernel files
The __cpuinit type of throwaway sections might have made sense
some time ago when RAM was more constrained, but now the savings
do not offset the cost and complications.  For example, the fix in
commit 5e427ec2d0 ("x86: Fix bit corruption at CPU resume time")
is a good example of the nasty type of bugs that can be created
with improper use of the various __init prefixes.

After a discussion on LKML[1] it was decided that cpuinit should go
the way of devinit and be phased out.  Once all the users are gone,
we can then finally remove the macros themselves from linux/init.h.

This removes all the uses of the __cpuinit macros from C files in
the core kernel directories (kernel, init, lib, mm, and include)
that don't really have a specific maintainer.

[1] https://lkml.org/lkml/2013/5/20/589

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
2013-07-14 19:36:59 -04:00
Linus Torvalds
f991fae5c6 Power management and ACPI updates for 3.11-rc1
- Hotplug changes allowing device hot-removal operations to fail
   gracefully (instead of crashing the kernel) if they cannot be
   carried out completely.  From Rafael J Wysocki and Toshi Kani.
 
 - Freezer update from Colin Cross and Mandeep Singh Baines targeted
   at making the freezing of tasks a bit less heavy weight operation.
 
 - cpufreq resume fix from Srivatsa S Bhat for a regression introduced
   during the 3.10 cycle causing some cpufreq sysfs attributes to
   return wrong values to user space after resume.
 
 - New freqdomain_cpus sysfs attribute for the acpi-cpufreq driver to
   provide information previously available via related_cpus from
   Lan Tianyu.
 
 - cpufreq fixes and cleanups from Viresh Kumar, Jacob Shin,
   Heiko Stübner, Xiaoguang Chen, Ezequiel Garcia, Arnd Bergmann, and
   Tang Yuantian.
 
 - Fix for an ACPICA regression causing suspend/resume issues to
   appear on some systems introduced during the 3.4 development cycle
   from Lv Zheng.
 
 - ACPICA fixes and cleanups from Bob Moore, Tomasz Nowicki, Lv Zheng,
   Chao Guan, and Zhang Rui.
 
 - New cupidle driver for Xilinx Zynq processors from Michal Simek.
 
 - cpuidle fixes and cleanups from Daniel Lezcano.
 
 - Changes to make suspend/resume work correctly in Xen guests from
   Konrad Rzeszutek Wilk.
 
 - ACPI device power management fixes and cleanups from Fengguang Wu
   and Rafael J Wysocki.
 
 - ACPI documentation updates from Lv Zheng, Aaron Lu and Hanjun Guo.
 
 - Fix for the IA-64 issue that was the reason for reverting commit
   9f29ab1 and updates of the ACPI scan code from Rafael J Wysocki.
 
 - Mechanism for adding CMOS RTC address space handlers from Lan Tianyu
   (to allow some EC-related breakage to be fixed on some systems).
 
 - Spec-compliant implementation of acpi_os_get_timer() from
   Mika Westerberg.
 
 - Modification of do_acpi_find_child() to execute _STA in order to
   to avoid situations in which a pointer to a disabled device object
   is returned instead of an enabled one with the same _ADR value.
   From Jeff Wu.
 
 - Intel BayTrail PCH (Platform Controller Hub) support for the ACPI
   Intel Low-Power Subsystems (LPSS) driver and modificaions of that
   driver to work around a couple of known BIOS issues from
   Mika Westerberg and Heikki Krogerus.
 
 - EC driver fix from Vasiliy Kulikov to make it use get_user() and
   put_user() instead of dereferencing user space pointers blindly.
 
 - Assorted ACPI code cleanups from Bjorn Helgaas, Nicholas Mazzuca and
   Toshi Kani.
 
 - Modification of the "runtime idle" helper routine to take the return
   values of the callbacks executed by it into account and to call
   rpm_suspend() if they return 0, which allows some code bloat
   reduction to be done, from Rafael J Wysocki and Alan Stern.
 
 - New trace points for PM QoS from Sahara <keun-o.park@windriver.com>.
 
 - PM QoS documentation update from Lan Tianyu.
 
 - Assorted core PM code cleanups and changes from Bernie Thompson,
   Bjorn Helgaas, Julius Werner, and Shuah Khan.
 
 - New devfreq driver for the Exynos5-bus device from Abhilash Kesavan.
 
 - Minor devfreq cleanups, fixes and MAINTAINERS update from
   MyungJoo Ham, Abhilash Kesavan, Paul Bolle, Rajagopal Venkat, and
   Wei Yongjun.
 
 - OMAP Adaptive Voltage Scaling (AVS) SmartReflex voltage control
   driver updates from Andrii Tseglytskyi and Nishanth Menon.
 
 /
 -----BEGIN PGP SIGNATURE-----
 Version: GnuPG v2.0.19 (GNU/Linux)
 
 iQIcBAABAgAGBQJR0ZNOAAoJEKhOf7ml8uNsDLYP/0EU4rmvw0TWTITfp6RS1KDE
 9GwBn96ZR4Q5bJd9gBCTPSqhHOYMqxWEUp99sn/M2wehG1pk/jw5LO56+2IhM3UZ
 g1HDcJ7te2nVT/iXsKiAGTVhU9Rk0aYwoVSknwk27qpIBGxW9w/s5tLX8pY3Q3Zq
 wL/7aTPjyL+PFFFEaxgH7qLqsl3DhbtYW5AriUBTkXout/tJ4eO1b7MNBncLDh8X
 VQ/0DNCKE95VEJfkO4rk9RKUyVp9GDn0i+HXCD/FS4IA5oYzePdVdNDmXf7g+swe
 CGlTZq8pB+oBpDiHl4lxzbNrKQjRNbGnDUkoRcWqn0nAw56xK+vmYnWJhW99gQ/I
 fKnvxeLca5po1aiqmC4VSJxZIatFZqLrZAI4dzoCLWY+bGeTnCKmj0/F8ytFnZA2
 8IuLLs7/dFOaHXV/pKmpg6FAlFa9CPxoqRFoyqb4M0GjEarADyalXUWsPtG+6xCp
 R/p0CISpwk+guKZR/qPhL7M654S7SHrPwd2DPF0KgGsvk+G2GhoB8EzvD8BVp98Z
 9siCGCdgKQfJQVI6R0k9aFmn/4gRQIAgyPhkhv9tqULUUkiaXki+/t8kPfnb8O/d
 zep+CA57E2G8MYLkDJfpFeKS7GpPD6TIdgFdGmOUC0Y6sl9iTdiw4yTx8O2JM37z
 rHBZfYGkJBrbGRu+Q1gs
 =VBBq
 -----END PGP SIGNATURE-----

Merge tag 'pm+acpi-3.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm

Pull power management and ACPI updates from Rafael Wysocki:
 "This time the total number of ACPI commits is slightly greater than
  the number of cpufreq commits, but Viresh Kumar (who works on cpufreq)
  remains the most active patch submitter.

  To me, the most significant change is the addition of offline/online
  device operations to the driver core (with the Greg's blessing) and
  the related modifications of the ACPI core hotplug code.  Next are the
  freezer updates from Colin Cross that should make the freezing of
  tasks a bit less heavy weight.

  We also have a couple of regression fixes, a number of fixes for
  issues that have not been identified as regressions, two new drivers
  and a bunch of cleanups all over.

  Highlights:

   - Hotplug changes to support graceful hot-removal failures.

     It sometimes is necessary to fail device hot-removal operations
     gracefully if they cannot be carried out completely.  For example,
     if memory from a memory module being hot-removed has been allocated
     for the kernel's own use and cannot be moved elsewhere, it's
     desirable to fail the hot-removal operation in a graceful way
     rather than to crash the kernel, but currenty a success or a kernel
     crash are the only possible outcomes of an attempted memory
     hot-removal.  Needless to say, that is not a very attractive
     alternative and it had to be addressed.

     However, in order to make it work for memory, I first had to make
     it work for CPUs and for this purpose I needed to modify the ACPI
     processor driver.  It's been split into two parts, a resident one
     handling the low-level initialization/cleanup and a modular one
     playing the actual driver's role (but it binds to the CPU system
     device objects rather than to the ACPI device objects representing
     processors).  That's been sort of like a live brain surgery on a
     patient who's riding a bike.

     So this is a little scary, but since we found and fixed a couple of
     regressions it caused to happen during the early linux-next testing
     (a month ago), nobody has complained.

     As a bonus we remove some duplicated ACPI hotplug code, because the
     ACPI-based CPU hotplug is now going to use the common ACPI hotplug
     code.

   - Lighter weight freezing of tasks.

     These changes from Colin Cross and Mandeep Singh Baines are
     targeted at making the freezing of tasks a bit less heavy weight
     operation.  They reduce the number of tasks woken up every time
     during the freezing, by using the observation that the freezer
     simply doesn't need to wake up some of them and wait for them all
     to call refrigerator().  The time needed for the freezer to decide
     to report a failure is reduced too.

     Also reintroduced is the check causing a lockdep warining to
     trigger when try_to_freeze() is called with locks held (which is
     generally unsafe and shouldn't happen).

   - cpufreq updates

     First off, a commit from Srivatsa S Bhat fixes a resume regression
     introduced during the 3.10 cycle causing some cpufreq sysfs
     attributes to return wrong values to user space after resume.  The
     fix is kind of fresh, but also it's pretty obvious once Srivatsa
     has identified the root cause.

     Second, we have a new freqdomain_cpus sysfs attribute for the
     acpi-cpufreq driver to provide information previously available via
     related_cpus.  From Lan Tianyu.

     Finally, we fix a number of issues, mostly related to the
     CPUFREQ_POSTCHANGE notifier and cpufreq Kconfig options and clean
     up some code.  The majority of changes from Viresh Kumar with bits
     from Jacob Shin, Heiko Stübner, Xiaoguang Chen, Ezequiel Garcia,
     Arnd Bergmann, and Tang Yuantian.

   - ACPICA update

     A usual bunch of updates from the ACPICA upstream.

     During the 3.4 cycle we introduced support for ACPI 5 extended
     sleep registers, but they are only supposed to be used if the
     HW-reduced mode bit is set in the FADT flags and the code attempted
     to use them without checking that bit.  That caused suspend/resume
     regressions to happen on some systems.  Fix from Lv Zheng causes
     those registers to be used only if the HW-reduced mode bit is set.

     Apart from this some other ACPICA bugs are fixed and code cleanups
     are made by Bob Moore, Tomasz Nowicki, Lv Zheng, Chao Guan, and
     Zhang Rui.

   - cpuidle updates

     New driver for Xilinx Zynq processors is added by Michal Simek.

     Multidriver support simplification, addition of some missing
     kerneldoc comments and Kconfig-related fixes come from Daniel
     Lezcano.

   - ACPI power management updates

     Changes to make suspend/resume work correctly in Xen guests from
     Konrad Rzeszutek Wilk, sparse warning fix from Fengguang Wu and
     cleanups and fixes of the ACPI device power state selection
     routine.

   - ACPI documentation updates

     Some previously missing pieces of ACPI documentation are added by
     Lv Zheng and Aaron Lu (hopefully, that will help people to
     uderstand how the ACPI subsystem works) and one outdated doc is
     updated by Hanjun Guo.

   - Assorted ACPI updates

     We finally nailed down the IA-64 issue that was the reason for
     reverting commit 9f29ab11dd ("ACPI / scan: do not match drivers
     against objects having scan handlers"), so we can fix it and move
     the ACPI scan handler check added to the ACPI video driver back to
     the core.

     A mechanism for adding CMOS RTC address space handlers is
     introduced by Lan Tianyu to allow some EC-related breakage to be
     fixed on some systems.

     A spec-compliant implementation of acpi_os_get_timer() is added by
     Mika Westerberg.

     The evaluation of _STA is added to do_acpi_find_child() to avoid
     situations in which a pointer to a disabled device object is
     returned instead of an enabled one with the same _ADR value.  From
     Jeff Wu.

     Intel BayTrail PCH (Platform Controller Hub) support is added to
     the ACPI driver for Intel Low-Power Subsystems (LPSS) and that
     driver is modified to work around a couple of known BIOS issues.
     Changes from Mika Westerberg and Heikki Krogerus.

     The EC driver is fixed by Vasiliy Kulikov to use get_user() and
     put_user() instead of dereferencing user space pointers blindly.

     Code cleanups are made by Bjorn Helgaas, Nicholas Mazzuca and Toshi
     Kani.

   - Assorted power management updates

     The "runtime idle" helper routine is changed to take the return
     values of the callbacks executed by it into account and to call
     rpm_suspend() if they return 0, which allows us to reduce the
     overall code bloat a bit (by dropping some code that's not
     necessary any more after that modification).

     The runtime PM documentation is updated by Alan Stern (to reflect
     the "runtime idle" behavior change).

     New trace points for PM QoS are added by Sahara
     (<keun-o.park@windriver.com>).

     PM QoS documentation is updated by Lan Tianyu.

     Code cleanups are made and minor issues are addressed by Bernie
     Thompson, Bjorn Helgaas, Julius Werner, and Shuah Khan.

   - devfreq updates

     New driver for the Exynos5-bus device from Abhilash Kesavan.

     Minor cleanups, fixes and MAINTAINERS update from MyungJoo Ham,
     Abhilash Kesavan, Paul Bolle, Rajagopal Venkat, and Wei Yongjun.

   - OMAP power management updates

     Adaptive Voltage Scaling (AVS) SmartReflex voltage control driver
     updates from Andrii Tseglytskyi and Nishanth Menon."

* tag 'pm+acpi-3.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (162 commits)
  cpufreq: Fix cpufreq regression after suspend/resume
  ACPI / PM: Fix possible NULL pointer deref in acpi_pm_device_sleep_state()
  PM / Sleep: Warn about system time after resume with pm_trace
  cpufreq: don't leave stale policy pointer in cdbs->cur_policy
  acpi-cpufreq: Add new sysfs attribute freqdomain_cpus
  cpufreq: make sure frequency transitions are serialized
  ACPI: implement acpi_os_get_timer() according the spec
  ACPI / EC: Add HP Folio 13 to ec_dmi_table in order to skip DSDT scan
  ACPI: Add CMOS RTC Operation Region handler support
  ACPI / processor: Drop unused variable from processor_perflib.c
  cpufreq: tegra: call CPUFREQ_POSTCHANGE notfier in error cases
  cpufreq: s3c64xx: call CPUFREQ_POSTCHANGE notfier in error cases
  cpufreq: omap: call CPUFREQ_POSTCHANGE notfier in error cases
  cpufreq: imx6q: call CPUFREQ_POSTCHANGE notfier in error cases
  cpufreq: exynos: call CPUFREQ_POSTCHANGE notfier in error cases
  cpufreq: dbx500: call CPUFREQ_POSTCHANGE notfier in error cases
  cpufreq: davinci: call CPUFREQ_POSTCHANGE notfier in error cases
  cpufreq: arm-big-little: call CPUFREQ_POSTCHANGE notfier in error cases
  cpufreq: powernow-k8: call CPUFREQ_POSTCHANGE notfier in error cases
  cpufreq: pcc: call CPUFREQ_POSTCHANGE notfier in error cases
  ...
2013-07-03 14:35:40 -07:00
Hanjun Guo
73e797f79e Documentation / CPU hotplug: Rephrase the outdated description for MADT entries
More than 256 entries in ACPI MADT is supported from ACPI 3.0, so the
information in should be Documentation/cpu-hotplug.txt updated.

[rjw: Changelog]
Suggested-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-06-21 13:42:17 +02:00
Stephen Rothwell
40b313608a Finally eradicate CONFIG_HOTPLUG
Ever since commit 45f035ab9b ("CONFIG_HOTPLUG should be always on"),
it has been basically impossible to build a kernel with CONFIG_HOTPLUG
turned off.  Remove all the remaining references to it.

Cc: Russell King <linux@arm.linux.org.uk>
Cc: Doug Thompson <dougthompson@xmission.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Acked-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-06-03 14:20:18 -07:00
Fenghua Yu
f78cff48c3 doc: Add x86 CPU0 online/offline feature
If CONFIG_BOOTPARAM_HOTPLUG_CPU0 is turned on, CPU0 is hotpluggable. Otherwise,
by default CPU0 is not hotpluggable and kernel parameter cpu0_hotplug enables
CPU0 online/offline feature.

The documentations point out two known CPU0 dependencies. First, resume from
hibernate or suspend always starts from CPU0. So hibernate and suspend are
prevented if CPU0 is offline. Another dependency is PIC interrupts always go
to CPU0.

It's said that some machines may depend on CPU0 to poweroff/reboot. But I
haven't seen such dependency on a few tested machines.

Please let me know if you see any CPU0 dependencies on your machine.

Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Link: http://lkml.kernel.org/r/1352835171-3958-2-git-send-email-fenghua.yu@intel.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2012-11-14 09:39:44 -08:00
Rusty Russell
5f054e31c6 documentation: remove references to cpu_*_map.
This has been obsolescent for a while, fix documentation and
misc comments.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2012-03-29 15:38:31 +10:30
Lucas De Marchi
25985edced Fix common misspellings
Fixes generated by 'codespell' and manually reviewed.

Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
2011-03-31 11:26:23 -03:00
Rusty Russell
d2800800d7 documentation: fix erroneous email address.
Hey, at least it has both l's.

Reported-by: Marin Mitov <mitov@issp.bas.bg>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2010-08-11 23:04:10 +09:30
Rusty Russell
4251417484 cpumask: don't recommend set_cpus_allowed hack in Documentation/cpu-hotplug.txt
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Gautham R Shenoy <ego@in.ibm.com>
Cc: Ashok Raj <ashok.raj@intel.com>
2009-12-17 11:43:29 +10:30
Gautham R Shenoy
3aa565f53c powerpc/pseries: Add hooks to put the CPU into an appropriate offline state
When a CPU is offlined on POWER currently, we call rtas_stop_self() and hand
the CPU back to the resource pool. This path is used for DLPAR which will
cause a change in the LPAR configuration which will be visible outside.

This patch changes the default state a CPU is put into when it is offlined.
On platforms which support ceding the processor to the hypervisor with
latency hint specifier value, during a cpu offline operation,
instead of calling rtas_stop_self(), we cede the vCPU to the hypervisor
while passing a latency hint specifier value. The Hypervisor can use this hint
to provide better energy savings. Also, during the offline
operation, the control of the vCPU remains with the LPAR as oppposed to
returning it to the resource pool.

The patch achieves this by creating an infrastructure to set the
preferred_offline_state() which can be either
- CPU_STATE_OFFLINE: which is the current behaviour of calling
  rtas_stop_self()

- CPU_STATE_INACTIVE: which cedes the vCPU to the hypervisor with the latency
  hint specifier.

The codepath which wants to perform a DLPAR operation can set the
preferred_offline_state() of a CPU to CPU_STATE_OFFLINE before invoking
cpu_down().

The patch also provides a boot-time command line argument to disable/enable
CPU_STATE_INACTIVE.

Signed-off-by: Gautham R Shenoy <ego@in.ibm.com>
Signed-off-by: Nathan Fontenot <nfont@austin.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2009-11-24 14:33:04 +11:00
Mike Travis
3b11ce7f54 x86: use possible_cpus=NUM to extend the possible cpus allowed
Impact: add new boot parameter

Use possible_cpus=NUM kernel parameter to extend the number of possible
cpus.

The ability to HOTPLUG ON cpus that are "possible" but not "present" is
dealt with in a later patch.

Signed-off-by: Mike Travis <travis@sgi.com>
2008-12-18 12:08:05 +01:00
Heiko Carstens
3ee1062b4e cpu hotplug: s390 doesn't support additional_cpus anymore.
s390 doesn't support the additional_cpus kernel parameter anymore since a
long time.  So we better update the code and documentation to reflect
that.

Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-08-12 16:07:28 -07:00
Heiko Carstens
48483b3290 [S390] Get rid of additional_cpus kernel parameter.
It caused only a lot of confusion. From now on cpu hotplug of up to
NR_CPUS will work by default. If somebody wants to limit that then
the possible_cpus parameter can be used.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2008-01-26 14:11:15 +01:00
Gautham R Shenoy
86ef5c9a8e cpu-hotplug: replace lock_cpu_hotplug() with get_online_cpus()
Replace all lock_cpu_hotplug/unlock_cpu_hotplug from the kernel and use
get_online_cpus and put_online_cpus instead as it highlights the
refcount semantics in these operations.

The new API guarantees protection against the cpu-hotplug operation, but
it doesn't guarantee serialized access to any of the local data
structures. Hence the changes needs to be reviewed.

In case of pseries_add_processor/pseries_remove_processor, use
cpu_maps_update_begin()/cpu_maps_update_done() as we're modifying the
cpu_present_map there.

Signed-off-by: Gautham R Shenoy <ego@in.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-25 21:08:02 +01:00
Cliff Wickman
470fd64644 hotplug cpu: migrate a task within its cpuset
When a cpu is disabled, move_task_off_dead_cpu() is called for tasks that have
been running on that cpu.

Currently, such a task is migrated:
 1) to any cpu on the same node as the disabled cpu, which is both online
    and among that task's cpus_allowed
 2) to any cpu which is both online and among that task's cpus_allowed

It is typical of a multithreaded application running on a large NUMA system to
have its tasks confined to a cpuset so as to cluster them near the memory that
they share.  Furthermore, it is typical to explicitly place such a task on a
specific cpu in that cpuset.  And in that case the task's cpus_allowed
includes only a single cpu.

This patch would insert a preference to migrate such a task to some cpu within
its cpuset (and set its cpus_allowed to its entire cpuset).

With this patch, migrate the task to:
 1) to any cpu on the same node as the disabled cpu, which is both online
    and among that task's cpus_allowed
 2) to any online cpu within the task's cpuset
 3) to any cpu which is both online and among that task's cpus_allowed

In order to do this, move_task_off_dead_cpu() must make a call to
cpuset_cpus_allowed_locked(), a new subset of cpuset_cpus_allowed(), that will
not block.  (name change - per Oleg's suggestion)

Calls are made to cpuset_lock() and cpuset_unlock() in migration_call() to set
the cpuset mutex during the whole migrate_live_tasks() and
migrate_dead_tasks() procedure.

[akpm@linux-foundation.org: build fix]
[pj@sgi.com: Fix indentation and spacing]
Signed-off-by: Cliff Wickman <cpw@sgi.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: Paul Jackson <pj@sgi.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Paul Jackson <pj@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 11:53:44 -07:00
Rafael J. Wysocki
8bb7844286 Add suspend-related notifications for CPU hotplug
Since nonboot CPUs are now disabled after tasks and devices have been
frozen and the CPU hotplug infrastructure is used for this purpose, we need
special CPU hotplug notifications that will help the CPU-hotplug-aware
subsystems distinguish normal CPU hotplug events from CPU hotplug events
related to a system-wide suspend or resume operation in progress.  This
patch introduces such notifications and causes them to be used during
suspend and resume transitions.  It also changes all of the
CPU-hotplug-aware subsystems to take these notifications into consideration
(for now they are handled in the same way as the corresponding "normal"
ones).

[oleg@tv-sign.ru: cleanups]
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Gautham R Shenoy <ego@in.ibm.com>
Cc: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-09 12:30:56 -07:00
Matt LaPlante
5d3f083d8f Fix typos in /Documentation : Misc
This patch fixes typos in various Documentation txts. The patch addresses some
misc words.

Signed-off-by: Matt LaPlante <kernel1@cyberdogtech.com>
Acked-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
2006-11-30 05:21:10 +01:00
Satoru Takeuchi
ca926e80dc [PATCH] doc: fixing cpu-hotplug documentation
Fixing cpu-hotplug documentation as follows:

 - moving confusing asterisk on additional_cpus descrition
 - fixing some typos
 - unifying indentation for source code and command line example

Signed-off-by: Satoru Takeuchi <takeuchi_satoru@jp.fujitsu.com>
Cc: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-20 10:26:43 -07:00
Chandra Seetharaman
7c7165c908 [PATCH] cpu hotplug: fix hotplug cpu documentation for proper usage
Update hotplug cpu documentation to clearly state when to use
register_cpu_notifier() and register_hotcpu_notifier.

Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-07-31 13:28:39 -07:00
KAMEZAWA Hiroyuki
3c30a75256 [PATCH] for_each_possible_cpu: documentaion
Replace for_each_cpu with for_each_possible_cpu.

Modifies occurences in documentaion.

for_each_cpu in whatisRCU.txt should be for_each_online_cpu ???
(I'm not sure..)

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-28 09:16:05 -08:00
Heiko Carstens
6303dbf570 [PATCH] cpu hotplug documentation fix
Looks like there was a merge conflict when patches
8f8b1138fc and
255acee706 were applied which wasn't properly
resolved. Fix this and add some additional description.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-02-20 20:00:10 -08:00
Heiko Carstens
37a3302618 [PATCH] s390: possible_cpus parameter
Introduce possible_cpus command line option.  Hard sets the number of bits set
in cpu_possible_map.  Unlike the additional_cpus parameter this one guarantees
that num_possible_cpus() will stay constant even if the system gets rebooted
and a different number of cpus are present at startup.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-02-17 13:59:27 -08:00
Heiko Carstens
255acee706 [PATCH] s390: additional_cpus parameter
Introduce additional_cpus command line option.  By default no additional cpu
can be attached to the system anymore.  Only the cpus present at IPL time can
be switched on/off.  If it is desired that additional cpus can be attached to
the system the maximum number of additional cpus needs to be specified with
this option.

This change is necessary in order to limit the waste of per_cpu data
structures.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-02-17 13:59:26 -08:00
Ashok Raj
8f8b1138fc [IA64] Count disabled cpus as potential hot-pluggable CPUs
Minor updates to earlier patch.
- Added to documentation to add ia64 as well.
- Minor clarification on how to use disabled cpus
- used plain max instead of max_t per Andew Morton.

Signed-off-by: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
2006-02-16 14:10:50 -08:00
Ashok Raj
c809406b4f [PATCH] Updated CPU hotplug documentation
Thanks to Nathan Lynch for the review and comments.  Thanks to Joel Schopp
for the pointer to add user space scipts.

Signed-off-by: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: Nathan Lynch <nathanl@austin.ibm.com>
Signed-off-by: Joel Schopp <jschopp@austin.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-08 20:13:55 -08:00