kgsl: Implement conservative scaling policy

This behaves similarly to the conservative cpufreq governor,
which is similar to how most Mali GPU scaling algorithms behave.

The "trustzone" policy that is default relies on an undocumented
black box to make scaling decisions.

How to enable:
echo conservative > /sys/devices/platform/kgsl-3d0.0/kgsl/kgsl-3d0/pwrscale/policy

Conservative attr group:
/sys/devices/platform/kgsl-3d0.0/kgsl/kgsl-3d0/pwrscale/policy_config/conservative

Polling interval (10-1000):
/sys/devices/platform/kgsl-3d0.0/kgsl/kgsl-3d0/pwrscale/policy_config/conservative/polling_interval

Enable stats printing (causes microlags on low polling intervals):
echo 1 > /sys/devices/platform/kgsl-3d0.0/kgsl/kgsl-3d0/pwrscale/policy_config/conservative/print_stats

NOTE:
- perms are set to 666 for testing purposes

Change-Id: I9d854a73981515fc9850104302804928b04c4687
Signed-off-by: Andrew Dodd <atd7@cornell.edu>
kgsl: conservative: change perms to 664

Change-Id: Ie023a6b0f3bf51c4c59030a79ae4ebbbce08201c
driver: lc898300: implement sysfs interface for vibrator intensity

Change-Id: I911796e1ccbe3bbe27d67c21a263b3ce65083dcc
sched: Reset rq->next_interval before going idle

next_balance, the point in jiffy time scale when a cpu will next load
balance, could have been calculated when the cpu was busy. A busy cpu
will apply its sched domain's busy_factor (usually > 1) in computing
next_balance for that sched domain, which causes the (busy) cpu to load
balance less frequently in its sched domains. However when the same cpu
is going idle, its next_balance needs to be reset without consideration
of busy_factor. Failure to do so would not trigger nohz idle balancer on
that cpu for unnecessarily long time (introducing additional scheduling
latencies for tasks). Fix bug in scheduler which aims to reset
next_balance before a cpu goes idle (as per existing comment) but is
clearly not doing so.

Change-Id: I7e027a51686528c4092d770c7d33c874d38f5df4
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>
Signed-off-by: Syed Rameez Mustafa <rameezmustafa@codeaurora.org>
sched: re-calculate a cpu's next_balance point upon sched domain changes

Commit 55ddeb0f (sched: Reset rq->next_interval before going idle) reset
a cpu's rq->next_balance when pulled_task = 0, which will be true when
the cpu failed to pull any task, causing it go idle. However that patch
relied on next_balance being calculated as a result of traversing cpu's
sched domain hierarchy.

A cpu that is the only online cpu will however not be attached to any
sched domain hierarchy. When such a cpu calls into idle_balance(), we
will end up initializing next_balance to be 1sec away! Such a CPU will
defer load balance check for another 1sec, even though we may bring up
more cpus in the meantime requiring it to check for load imbalance more
frequently. This could then lead to increased scheduling latency for
some tasks.

This patch results in a cpu's next_balance being re-calculated when its
attaching to a new sched domain hierarchy.  This should let cpus call
load balance checks at the right time we expect them to!

Change-Id: I855cff8da5ca28d278596c3bb0163b839d4704bc
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>
Signed-off-by: Syed Rameez Mustafa <rameezmustafa@codeaurora.org>
sched: Make sure to not re-read variables after validation

We could re-read rq->rt_avg after we validated it was smaller than
total, invalidating the check and resulting in an unintended negative.

Change-Id: I8543974aad539107768e9e513ca3a8c4cb79b2ff
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: David Rientjes <rientjes@google.com>
Link: http://lkml.kernel.org/r/1337688268.9698.29.camel@twins
Signed-off-by: Ingo Molnar <mingo@kernel.org>
CRs-Fixed: 497236
Git-commit: b654f7de41b0e3903ee2b51d3b8db77fe52ce728
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>
Signed-off-by: Syed Rameez Mustafa <rameezmustafa@codeaurora.org>
ARM: 7486/1: sched_clock: update epoch_cyc on resume

Many clocks that are used to provide sched_clock will reset during
suspend.  If read_sched_clock returns 0 after suspend, sched_clock will
appear to jump forward.  This patch resets cd.epoch_cyc to the current
value of read_sched_clock during resume, which causes sched_clock() just
after suspend to return the same value as sched_clock() just before
suspend.

In addition, during the window where epoch_ns has been updated before
suspend, but epoch_cyc has not been updated after suspend, it is unknown
whether the clock has reset or not, and sched_clock() could return a
bogus value.  Add a suspended flag, and return the pre-suspend epoch_ns
value during this period.

The new behavior is triggered by calling setup_sched_clock_needs_suspend
instead of setup_sched_clock.

Change-Id: I7441ef74dc6802c00eea61f3b8c0a25ac00a724d
Signed-off-by: Colin Cross <ccross@android.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
CRs-Fixed: 497236
Git-commit: 237ec6f2e51d2fc2ff37c7c5f1ccc9264d09c85b
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>
Signed-off-by: Syed Rameez Mustafa <rameezmustafa@codeaurora.org>
ARM: 7565/1: sched: stop sched_clock() during suspend

The scheduler imposes a requirement to sched_clock()
which is to stop the clock during suspend, if we don't
do that any RT thread will be rescheduled in the future
which might cause any sort of problems.

This became an issue on OMAP when we converted omap-i2c.c
to use threaded IRQs, it turned out that depending on how
much time we spent on suspend, the I2C IRQ thread would
end up being rescheduled so far in the future that I2C
transfers would timeout and, because omap_hsmmc depends
on an I2C-connected device to detect if an MMC card is
inserted in the slot, our rootfs would just vanish.

arch/arm/kernel/sched_clock.c already had an optional
implementation (sched_clock_needs_suspend()) which would
handle scheduler's requirement properly, what this patch
does is simply to make that implementation non-optional.

Note that this has the side-effect that printk timings
won't reflect the actual time spent on suspend so other
methods to measure that will have to be used.

This has been tested with beagleboard XM (OMAP3630) and
pandaboard rev A3 (OMAP4430). Suspend to RAM is now working
after this patch.

Thanks to Kevin Hilman for helping out with debugging.

Change-Id: Ie2f9e3b22eb3d1f3806cf8c598f22e2fa1b8651f
Acked-by: Kevin Hilman <khilman@ti.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
CRs-Fixed: 497236
Git-commit: 6a4dae5e138a32b45ca5218cc2b81802f9d378c3
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>
Signed-off-by: Syed Rameez Mustafa <rameezmustafa@codeaurora.org>
ARM: 7643/1: sched: correct update_sched_clock()

If we want load epoch_cyc and epoch_ns atomically,
we should update epoch_cyc_copy first of all.
This notify reader that updating is in progress.

If we update epoch_cyc first like as current implementation,
there is subtle error case.
Look at the below example.

<Initial Condition>
cyc = 9
ns = 900
cyc_copy = 9

== CASE 1 ==
<CPU A = reader>           <CPU B = updater>
                           write cyc = 10
read cyc = 10
read ns = 900
                           write ns = 1000
                           write cyc_copy = 10
read cyc_copy = 10

output = (10, 900)

== CASE 2 ==
<CPU A = reader>           <CPU B = updater>
read cyc = 9
                           write cyc = 10
                           write ns = 1000
read ns = 1000
read cyc_copy = 9
                           write cyc_copy = 10
output = (9, 1000)

If atomic read is ensured, output should be (9, 900) or (10, 1000).
But, output in example case are not.

So, change updating sequence in order to correct this problem.

Change-Id: Ia9196dd50a519f516f70c3138233624b669ef96a
Cc: <stable@vger.kernel.org>
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
CRs-Fixed: 497236
Git-commit: 7c4e9ced424be4d36df6a3e3825763e97ee97607
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>
Signed-off-by: Syed Rameez Mustafa <rameezmustafa@codeaurora.org>
sched: Set MC (multi-core) sched domain's busy_factor attribute to 1

busy_factor attribute of a scheduler domain causes busy CPUs (CPUs
that are not idle) to load balance less frequently in that domain,
which could impact performance by increasing scheduling latency for
tasks.

As an example, consider MC scheduler domain's attribute values of
max_interval = 4ms and busy_factor = 64. Further consider
max_load_balance_interval = 100 (HZ/10). In this case, a non-idle CPU
could put off load balance check in MC domain by 100ms. This
effectively means that a CPU running a single task in its queue could
fail to notice increased load on another CPU (that is in same MC
domain) for upto 100ms, before picking up load from the overloaded
CPU. Needless to say, this leads to increased scheduling latency for
tasks, affecting performance adversely.

By setting MC domain's busy_factor value to 1, we limit maximum
interval that busy CPU can put off load balance checks to 4ms
(effectively 10ms, given HZ value of 100).

Change-Id: Id45869d06f5556ea8eec602b65c2ffd2143fe060
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>
Signed-off-by: Syed Rameez Mustafa <rameezmustafa@codeaurora.org>
sched: Unthrottle rt runqueues in __disable_runtime()

migrate_tasks() uses _pick_next_task_rt() to get tasks from the
real-time runqueues to be migrated. When rt_rq is throttled
_pick_next_task_rt() won't return anything, in which case
migrate_tasks() can't move all threads over and gets stuck in an
infinite loop.

Instead unthrottle rt runqueues before migrating tasks.

Additionally: move unthrottle_offline_cfs_rqs() to rq_offline_fair()

Change-Id: If8a4a399f1a14b7f4789c1b205dcfadbde555214
Signed-off-by: Peter Boonstoppel <pboonstoppel@nvidia.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Turner <pjt@google.com>
Link: http://lkml.kernel.org/r/5FBF8E85CA34454794F0F7ECBA79798F379D3648B7@HQMAIL04.nvidia.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Git-commit: a4c96ae319b8047f62dedbe1eac79e321c185749
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
Signed-off-by: Syed Rameez Mustafa <rameezmustafa@codeaurora.org>