linux-toradex.git/kernel/sched.c, branch v2.6.19.3

[PATCH] sched: fix cond_resched_softirq() offset

2007-02-05T16:31:45+00:00

Remove the __resched_legal() check: it is conceptually broken.  The biggest
problem it had is that it can mask buggy cond_resched() calls.  A
cond_resched() call is only legal if we are not in an atomic context, with
two narrow exceptions:

 - if the system is booting
 - a reacquire_kernel_lock() down() done while PREEMPT_ACTIVE is set

But __resched_legal() hid this and just silently returned whenever
these primitives were called from invalid contexts. (Same goes for
cond_resched_locked() and cond_resched_softirq()).

Furthermore, the __legal_resched(0) call was buggy in that it caused
unnecessarily long softirq latencies via cond_resched_softirq().  (which is
only called from softirq-off sections, hence the code did nothing.)

The fix is to resurrect the efficiency of the might_sleep checks and to
only allow the narrow exceptions.

Signed-off-by: Ingo Molnar 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
[chrisw: backport to 2.6.19.2]
Signed-off-by: Chris Wright

[PATCH] move_task_off_dead_cpu() should be called with disabled ints

2007-02-05T16:31:45+00:00

move_task_off_dead_cpu() requires interrupts to be disabled, while
migrate_dead() calls it with enabled interrupts.  Added appropriate
comments to functions and added BUG_ON(!irqs_disabled()) into
double_rq_lock() and double_lock_balance() which are the origin sources of
such bugs.

Signed-off-by: Kirill Korotaev 
Acked-by: Ingo Molnar 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Chris Wright

[PATCH] sched: tasks cannot run on cpus onlined after boot

2007-02-05T16:31:40+00:00

Commit 5c1e176781f43bc902a51e5832f789756bff911b ("sched: force /sbin/init
off isolated cpus") sets init's cpus_allowed to a subset of cpu_online_map
at boot time, which means that tasks won't be scheduled on cpus that are
added to the system later.

Make init's cpus_allowed a subset of cpu_possible_map instead.  This should
still preserve the behavior that Nick's change intended.

Thanks to Giuliano Pochini for reporting this and testing the fix:

http://ozlabs.org/pipermail/linuxppc-dev/2006-December/029397.html

Signed-off-by: Nathan Lynch 
Acked-by: Ingo Molnar 
Cc: Nick Piggin 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Chris Wright

[PATCH] sched: remove __cpuinitdata anotation to cpu_isolated_map

2007-01-10T19:05:18+00:00

The structure cpu_isolated_map is used not only during initialization.
Multi-core scheduler configuration changes and exclusive cpusets
use this during run time.  During setting of sched_mc_power_savings
 policy, this structure is accessed to update sched_domains.

Signed-off-by: Tim Chen 
Acked-by: Suresh Siddha 
Acked-by: Ingo Molnar 
Signed-off-by: Chris Wright

[PATCH] readjust comments of task_timeslice for kernel doc

2006-10-20T17:26:37+00:00

Signed-off-by: Borislav Petkov 
Acked-by: Ingo Molnar 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] sched: likely profiling

2006-10-11T18:14:22+00:00

This likely profiling is pretty fun. I found a few possible problems
in sched.c.

This patch may be not measurable, but when I did measure long ago,
nooping (un)likely cost a couple of % on scheduler heavy benchmarks, so
it all adds up.

Tweak some branch hints:

- the 2nd 64 bits in the bitmask is likely to be populated, because it
  contains the first 28 bits (nearly 3/4) of the normal priorities.
  (ratio of 669669:691 ~= 1000:1).

- it isn't unlikely that context switching switches to another process. it
  might be very rapidly switching to and from the idle process (ratio of
  475815:419004 and 471330:423544). Let the branch predictor decide.

- preempt_enable seems to be very often called in a nested preempt_disable
  or with interrupts disabled (ratio of 3567760:87965 ~= 40:1)

Signed-off-by: Nick Piggin 
Acked-by: Ingo Molnar 
Cc: Daniel Walker 
Cc: Hua Zhong 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] scheduler: NUMA aware placement of sched_group_allnodes

2006-10-03T15:04:07+00:00

When the per cpu sched domains are build then they also need to be placed
on the node where the cpu resides otherwise we will have frequent off node
accesses which will slow down the system.

Signed-off-by: Christoph Lameter 
Acked-by: Ingo Molnar 
Acked-by: Nick Piggin 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] sched: fixing wrong comment for find_idlest_cpu()

2006-10-03T15:04:07+00:00

Fixing wrong comment for find_idlest_cpu().

Signed-off-by: Satoru Takeuchi 
Acked-by: Ingo Molnar 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] sched: cleanup sched_group cpu_power setup

2006-10-03T15:04:06+00:00

Up to now sched group's cpu_power for each sched domain is initialized
independently.  This made the setup code ugly as the new sched domains are
getting added.

Make the sched group cpu_power setup code generic, by using domain child
field and new domain flag in sched_domain.  For most of the sched
domains(except NUMA), sched group's cpu_power is now computed generically
using the domain properties of itself and of the child domain.

sched groups in NUMA domains are setup little differently and hence they
don't use this generic mechanism.

Signed-off-by: Suresh Siddha 
Acked-by: Ingo Molnar 
Acked-by: Nick Piggin 
Cc: Paul Jackson 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] sched: introduce child field in sched_domain

2006-10-03T15:04:06+00:00

Introduce the child field in sched_domain struct and use it in
sched_balance_self().

We will also use this field in cleaning up the sched group cpu_power
setup(done in a different patch) code.

Signed-off-by: Suresh Siddha 
Acked-by: Ingo Molnar 
Acked-by: Nick Piggin 
Cc: Paul Jackson 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds