linux/init
Max Krasnyansky e761b77252 cpu hotplug, sched: Introduce cpu_active_map and redo sched domain managment (take 2)
This is based on Linus' idea of creating cpu_active_map that prevents
scheduler load balancer from migrating tasks to the cpu that is going
down.

It allows us to simplify domain management code and avoid unecessary
domain rebuilds during cpu hotplug event handling.

Please ignore the cpusets part for now. It needs some more work in order
to avoid crazy lock nesting. Although I did simplfy and unify domain
reinitialization logic. We now simply call partition_sched_domains() in
all the cases. This means that we're using exact same code paths as in
cpusets case and hence the test below cover cpusets too.
Cpuset changes to make rebuild_sched_domains() callable from various
contexts are in the separate patch (right next after this one).

This not only boots but also easily handles
	while true; do make clean; make -j 8; done
and
	while true; do on-off-cpu 1; done
at the same time.
(on-off-cpu 1 simple does echo 0/1 > /sys/.../cpu1/online thing).

Suprisingly the box (dual-core Core2) is quite usable. In fact I'm typing
this on right now in gnome-terminal and things are moving just fine.

Also this is running with most of the debug features enabled (lockdep,
mutex, etc) no BUG_ONs or lockdep complaints so far.

I believe I addressed all of the Dmitry's comments for original Linus'
version. I changed both fair and rt balancer to mask out non-active cpus.
And replaced cpu_is_offline() with !cpu_active() in the main scheduler
code where it made sense (to me).

Signed-off-by: Max Krasnyanskiy <maxk@qualcomm.com>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Gregory Haskins <ghaskins@novell.com>
Cc: dmitry.adamushko@gmail.com
Cc: pj@sgi.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-07-18 13:22:25 +02:00
..
calibrate.c x86: use cpu_khz for loops_per_jiffy calculation, cleanup 2008-06-24 13:53:46 +02:00
do_mounts_initrd.c Freezer: Fix s2disk resume from initrd 2007-11-20 22:22:42 -05:00
do_mounts_md.c md: proper extern for mdp_major 2008-05-24 09:56:09 -07:00
do_mounts_rd.c init: fix integer as NULL pointer warnings 2008-04-28 17:29:18 -07:00
do_mounts.c do_mounts: allow UBI root device name 2008-07-14 19:10:52 +03:00
do_mounts.h Remove all inclusions of <linux/config.h> 2006-10-04 03:38:54 -04:00
initramfs.c directly use kmalloc() and kfree() in init/initramfs.c 2008-04-29 08:06:06 -07:00
Kconfig Kconfig: introduce ARCH_DEFCONFIG to DEFCONFIG_LIST 2008-05-25 23:03:18 +02:00
main.c cpu hotplug, sched: Introduce cpu_active_map and redo sched domain managment (take 2) 2008-07-18 13:22:25 +02:00
Makefile kbuild: fix make V=1 2008-02-11 17:43:54 +01:00
noinitramfs.c [PATCH] disable init/initramfs.c 2007-02-11 10:51:25 -08:00
version.c [PATCH] remove many unneeded #includes of sched.h 2007-02-14 08:09:54 -08:00