hrtimer: Consider preemption when migrating hrtimer cpu_bases

Date	Wed, 10 Apr 2013 14:07:47 -0700

When switching to a new cpu_base in switch_hrtimer_base(), we
briefly enable preemption by unlocking the cpu_base lock in two
places. During this interval it's possible for the running thread
to be swapped to a different CPU.

Consider the following example:

CPU #0                                 CPU #1
----                                   ----
hrtimer_start()                        ...
 lock_hrtimer_base()
 switch_hrtimer_base()
  this_cpu = 0;
  target_cpu_base = 0;
  raw_spin_unlock(&cpu_base->lock)
<migrate to CPU 1>
...                                    this_cpu == 0
                                       cpu == this_cpu
                                       timer->base = CPU #0
                                       timer->base != LOCAL_CPU
Since the cached this_cpu is no longer accurate, we'll skip the
hrtimer_check_target() check. Once we eventually go to program
the hardware, we'll decide not to do so since it knows the real
CPU that we're running on is not the same as the chosen base. As
a consequence, we may end up missing the hrtimer's deadline.

Fix this by updating the local CPU number each time we retake a
cpu_base lock in switch_hrtimer_base().

Another possibility is to disable preemption across the whole of
switch_hrtimer_base. This looks suboptimal since preemption
would be disabled while waiting for lock(s).

Signed-off-by: Michael Bohan <mbohan@codeaurora.org>
hrtimer: Prevent enqueue of hrtimer on dead CPU

Date	Wed, 10 Apr 2013 14:07:48 -0700

When switching the hrtimer cpu_base, we briefly allow for
preemption to become enabled by unlocking the cpu_base lock.
During this time, the CPU corresponding to the new cpu_base
that was selected may in fact go offline. In this scenario, the
hrtimer is enqueued to a CPU that's not online, and therefore
it never fires.

As an example, consider this example:

CPU #0                          CPU #1
----                            ----
...                             hrtimer_start()
                                 lock_hrtimer_base()
                                 switch_hrtimer_base()
                                  cpu = hrtimer_get_target() -> 1
                                  spin_unlock(&cpu_base->lock)
                                <migrate thread to CPU #0>
                                <offline>
spin_lock(&new_base->lock)
this_cpu = 0
cpu != this_cpu
enqueue_hrtimer(cpu_base #1)
To prevent this scenario, verify that the CPU corresponding to
the new cpu_base is indeed online before selecting it in
hrtimer_switch_base(). If it's not online, fallback to using the
base of the current CPU.

Signed-off-by: Michael Bohan <mbohan@codeaurora.org>
intellidemand: tweak optimal for krait 600 series

Signed-off-by: Paul Reioux <reioux@gmail.com>
SCHEDULER: Autogroup patch group by current user android UID instead of task ID
init/Kconfig: decouple DEBUG_KERNEL from EXPERT settings

Signed-off-by: Paul Reioux <reioux@gmail.com>
intellidemand: enable sec_touchscreen input boosting

Signed-off-by: Paul Reioux <reioux@gmail.com>
intellidemand: set default sampling rate to 50k

Signed-off-by: Paul Reioux <reioux@gmail.com>
sched: Optimize build_sched_domains() for saving first SD node for a cpu

Date	Tue, 4 Jun 2013 16:50:18 +0530

We are saving first scheduling domain for a cpu in build_sched_domains() by
iterating over the nested sd->child list. We don't actually need to do it this
way.

*per_cpu_ptr(d.sd, i) is guaranteed to be NULL in the beginning as we have
called __visit_domain_allocation_hell() which does a memset to zero for struct
s_data.

So, save pointer to first SD while running the iteration loop over tl's.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Paul Reioux <reioux@gmail.com>
sched: Optimize build_sched_domains() for saving first SD node for a cpu

We are saving first scheduling domain for a cpu in build_sched_domains() by
iterating over the nested sd->child list. We don't actually need to do it this
way.

tl will be equal to sched_domain_topology for the first iteration and so we can
set *per_cpu_ptr(d.sd, i) based on that.  So, save pointer to first SD while
running the iteration loop over tl's.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Paul Reioux <reioux@gmail.com>
sched: Remove unused params of build_sched_domain()

Date	Tue, 4 Jun 2013 16:50:19 +0530

build_sched_domain() never uses parameter struct s_data *d and so passing it is
useless.

Remove it.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Paul Reioux <reioux@gmail.com>
ARM: fault: assume no context when IRQs are disabled during data abort.

Bail out early if IRQs are disabled in do_page_fault or else
  [14415.157266] BUG: sleeping function called from invalid context at arch/arm/mm/fault.c:301

Russell King's idea from
  http://comments.gmane.org/gmane.linux.ports.arm.omap/59256

Signed-off-by: JP Abgrall <jpa@google.com>
mm: Clear page active before releasing pages

Active pages should not be freed to the page allocator as it triggers
a bad page state warning. Fengguang Wu reported the following
bug and bisected it to the patch "mm: remove lru parameter from
__lru_cache_add and lru_cache_add_lru" which is currently in mmotm as
mm-remove-lru-parameter-from-__lru_cache_add-and-lru_cache_add_lru.patch

[   84.212960] BUG: Bad page state in process rm  pfn:0b0c9
[   84.214682] page:ffff88000d646240 count:0 mapcount:0 mapping:          (null) index:0x0
[   84.216883] page flags: 0x20000000004c(referenced|uptodate|active)
[   84.218697] CPU: 1 PID: 283 Comm: rm Not tainted 3.10.0-rc4-04361-geeb9bfc #49
[   84.220729]  ffff88000d646240 ffff88000d179bb8 ffffffff82562956 ffff88000d179bd8
[   84.223242]  ffffffff811333f1 000020000000004c ffff88000d646240 ffff88000d179c28
[   84.225387]  ffffffff811346a4 ffff880000270000 0000000000000000 0000000000000006
[   84.227294] Call Trace:
[   84.227867]  [<ffffffff82562956>] dump_stack+0x27/0x30
[   84.229045]  [<ffffffff811333f1>] bad_page+0x130/0x158
[   84.230261]  [<ffffffff811346a4>] free_pages_prepare+0x8b/0x1e3
[   84.231765]  [<ffffffff8113542a>] free_hot_cold_page+0x28/0x1cf
[   84.233171]  [<ffffffff82585830>] ? _raw_spin_unlock_irqrestore+0x6b/0xc6
[   84.234822]  [<ffffffff81135b59>] free_hot_cold_page_list+0x30/0x5a
[   84.236311]  [<ffffffff8113a4ed>] release_pages+0x251/0x267
[   84.237653]  [<ffffffff8112a88d>] ? delete_from_page_cache+0x48/0x9e
[   84.239142]  [<ffffffff8113ad93>] __pagevec_release+0x2b/0x3d
[   84.240473]  [<ffffffff8113b45a>] truncate_inode_pages_range+0x1b0/0x7ce
[   84.242032]  [<ffffffff810e76ab>] ? put_lock_stats.isra.20+0x1c/0x53
[   84.243480]  [<ffffffff810e77f5>] ? lock_release_holdtime+0x113/0x11f
[   84.244935]  [<ffffffff8113ba8c>] truncate_inode_pages+0x14/0x1d
[   84.246337]  [<ffffffff8119b3ef>] evict+0x11f/0x232
[   84.247501]  [<ffffffff8119c527>] iput+0x1a5/0x218
[   84.248607]  [<ffffffff8118f015>] do_unlinkat+0x19b/0x25a
[   84.249828]  [<ffffffff810ea993>] ? trace_hardirqs_on_caller+0x210/0x2ce
[   84.251382]  [<ffffffff8144372e>] ? trace_hardirqs_on_thunk+0x3a/0x3f
[   84.252879]  [<ffffffff8118f10d>] SyS_unlinkat+0x39/0x4c
[   84.254174]  [<ffffffff825874d6>] system_call_fastpath+0x1a/0x1f
[   84.255596] Disabling lock debugging due to kernel taint
The problem was that a page marked for activation was released via
pagevec. This patch clears the active bit before freeing in this case.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Reported-and-Tested-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Paul Reioux <reioux@gmail.com>
sched: Use cached value of span instead of calling sched_domain_span()

Date	Tue, 11 Jun 2013 16:32:43 +0530

In the beginning of build_sched_groups() we called sched_domain_span() and
cached its return value in span. Few statements later we are calling it again to
get the same pointer.

Lets use the cached value instead as it hasn't changed in between.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Paul Reioux <reioux@gmail.com>
sched: don't call get_group() for covered cpus

Date	Tue, 11 Jun 2013 16:32:44 +0530

In build_sched_groups() we don't need to call get_group() for cpus which are
already covered in previous iterations. So, call get_group() after checking if
cpu is covered or not.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Paul Reioux <reioux@gmail.com>
sched: remove WARN_ON(!sd) from init_sched_groups_power()

Date	Tue, 11 Jun 2013 16:32:45 +0530

sd can't be NULL in init_sched_groups_power() and so checking it for NULL isn't
useful. In case it is required, then also we need to rearrange the code a bit as
we already accessed invalid pointer sd to get sg: sg = sd->groups.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Paul Reioux <reioux@gmail.com>
sched: reduce calculation effort in fix_small_imbalance

Date	Mon, 17 Jun 2013 21:00:22 +0800

Actually all below item could be repalced by scaled_busy_load_per_task
	(sds->busiest_load_per_task * SCHED_POWER_SCALE)
		/sds->busiest->sgp->power;

Signed-off-by: Lei Wen <leiwen@marvell.com>
Signed-off-by: Paul Reioux <reioux@gmail.com>
sched: scale the busy and this queue's per-task load before compare

Date	Mon, 17 Jun 2013 21:00:23 +0800

Since for max_load and this_load, they are the value that already be
scaled. It is not reasonble to get a minimum value between the scaled
and non-scaled value, like below example.
	min(sds->busiest_load_per_task, sds->max_load);

Also add comment over in what condition, there would be cpu power gain
in move the load.

Signed-off-by: Lei Wen <leiwen@marvell.com>
Signed-off-by: Paul Reioux <reioux@gmail.com>
sched: scale cpu load for judgment of group imbalance

Date	Mon, 17 Jun 2013 21:00:24 +0800

We cannot compare two load directly from two cpus, since the cpu power
over two cpu may vary largely.

Suppose we meet such two kind of cpus.
CPU A:
	No real time work, and there are 3 task, with rq->load.weight
being 512.
CPU B:
	Has real time work, and it take 3/4 of the cpu power, which
makes CFS only take 1/4, that is 1024/4=256 cpu power. And over its CFS
runqueue, there is only one task with weight as 128.

Since both cpu's CFS task take for half of the CFS's cpu power, it
should be considered as balanced in such case.

But original judgment like:
        if ((max_cpu_load - min_cpu_load) >= avg_load_per_task &&
            (max_nr_running - min_nr_running) > 1)
It makes (512-128)>=((512+128)/4), and lead to imbalance conclusion...
Make the load as scaled, to avoid such case.

Signed-off-by: Lei Wen <leiwen@marvell.com>

modified for Mako kernel from LKML reference
Signed-off-by: Paul Reioux <reioux@gmail.com>
intellidemand: re-enable performance lock option

with low freq enabled kernels, minimum performance lock will help music
playback to be smooth and glitch free

Signed-off-by: Paul Reioux <reioux@gmail.com>
Intellidemand: limit min cpu perflock to boot cpu only

Signed-off-by: Paul Reioux <reioux@gmail.com>