Add gitignore

Conflicts:

	.gitignore
lib/int_sqrt.c: optimize square root algorithm

Optimize the current version of the shift-and-subtract (hardware)
algorithm, described by John von Newmann[1] and Guy L Steele.

Iterating 1,000,000 times, perf shows for the current version:

 Performance counter stats for './sqrt-curr' (10 runs):

         27.170996 task-clock                #    0.979 CPUs utilized            ( +-  3.19% )
                 3 context-switches          #    0.103 K/sec                    ( +-  4.76% )
                 0 cpu-migrations            #    0.004 K/sec                    ( +-100.00% )
               104 page-faults               #    0.004 M/sec                    ( +-  0.16% )
        64,921,199 cycles                    #    2.389 GHz                      ( +-  0.03% )
        28,967,789 stalled-cycles-frontend   #   44.62% frontend cycles idle     ( +-  0.18% )
   <not supported> stalled-cycles-backend
       104,502,623 instructions              #    1.61  insns per cycle
                                             #    0.28  stalled cycles per insn  ( +-  0.00% )
        34,088,368 branches                  # 1254.587 M/sec                    ( +-  0.00% )
             4,901 branch-misses             #    0.01% of all branches          ( +-  1.32% )

       0.027763015 seconds time elapsed                                          ( +-  3.22% )

And for the new version:

Performance counter stats for './sqrt-new' (10 runs):

          0.496869 task-clock                #    0.519 CPUs utilized            ( +-  2.38% )
                 0 context-switches          #    0.000 K/sec
                 0 cpu-migrations            #    0.403 K/sec                    ( +-100.00% )
               104 page-faults               #    0.209 M/sec                    ( +-  0.15% )
           590,760 cycles                    #    1.189 GHz                      ( +-  2.35% )
           395,053 stalled-cycles-frontend   #   66.87% frontend cycles idle     ( +-  3.67% )
   <not supported> stalled-cycles-backend
           398,963 instructions              #    0.68  insns per cycle
                                             #    0.99  stalled cycles per insn  ( +-  0.39% )
            70,228 branches                  #  141.341 M/sec                    ( +-  0.36% )
             3,364 branch-misses             #    4.79% of all branches          ( +-  5.45% )

       0.000957440 seconds time elapsed                                          ( +-  2.42% )

Furthermore, this saves space in instruction text:

   text    data     bss     dec     hex filename
    111       0       0     111      6f lib/int_sqrt-baseline.o
     89       0       0      89      59 lib/int_sqrt.o

[1] http://en.wikipedia.org/wiki/First_Draft_of_a_Report_on_the_EDVAC

Signed-off-by: Davidlohr Bueso <davidlohr.bueso@hp.com>
Reviewed-by: Jonathan Gonzalez <jgonzlez@linets.cl>
Tested-by: Jonathan Gonzalez <jgonzlez@linets.cl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Francisco Franco <franciscofranco.1990@gmail.com>
cpufreq: Manage only online cpus

cpufreq core doesn't manage offline cpus and if driver->init() has returned
mask including offline cpus, it may result in unwanted behavior by cpufreq core
or governors.

We need to get only online cpus in this mask. There are two places to fix this
mask, cpufreq core and cpufreq driver. It makes sense to do this at common place
and hence is done in core.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Francisco Franco <franciscofranco.1990@gmail.com>
writeback: fix writeback cache thrashing

From: Namjae Jeon <namjae.jeon@samsung.com>

Consider Process A: huge I/O on sda
        doing heavy write operation - dirty memory becomes more
        than dirty_background_ratio
        on HDD - flusher thread flush-8:0

Consider Process B: small I/O on sdb
        doing while [1]; read 1024K + rewrite 1024K + sleep 2sec
        on Flash device - flusher thread flush-8:16

As Process A is a heavy dirtier, dirty memory becomes more
than dirty_background_thresh. Due to this, below check becomes
true(checking global_page_state in over_bground_thresh)
for all bdi devices(even for very small dirtied bdi - sdb):

In this case, even small cached data on 'sdb' is forced to flush
and writeback cache thrashing happens.

When we added debug prints inside above 'if' condition and ran
above Process A(heavy dirtier on bdi with flush-8:0) and
Process B(1024K frequent read/rewrite on bdi with flush-8:16)
we got below prints:

[Test setup: ARM dual core CPU, 512 MB RAM]

[over_bground_thresh]: wakeup flush-8:0 : BDI_RECLAIMABLE =  56064 KB
[over_bground_thresh]: wakeup flush-8:0 : BDI_RECLAIMABLE =  56704 KB
[over_bground_thresh]: wakeup flush-8:0 : BDI_RECLAIMABLE = 84720 KB
[over_bground_thresh]: wakeup flush-8:0 : BDI_RECLAIMABLE = 94720 KB
[over_bground_thresh]: wakeup flush-8:16 : BDI_RECLAIMABLE =   384 KB
[over_bground_thresh]: wakeup flush-8:16 : BDI_RECLAIMABLE =   960 KB
[over_bground_thresh]: wakeup flush-8:16 : BDI_RECLAIMABLE =    64 KB
[over_bground_thresh]: wakeup flush-8:0 : BDI_RECLAIMABLE = 92160 KB
[over_bground_thresh]: wakeup flush-8:16 : BDI_RECLAIMABLE =   256 KB
[over_bground_thresh]: wakeup flush-8:16 : BDI_RECLAIMABLE =   768 KB
[over_bground_thresh]: wakeup flush-8:16 : BDI_RECLAIMABLE =    64 KB
[over_bground_thresh]: wakeup flush-8:16 : BDI_RECLAIMABLE =   256 KB
[over_bground_thresh]: wakeup flush-8:16 : BDI_RECLAIMABLE =   320 KB
[over_bground_thresh]: wakeup flush-8:16 : BDI_RECLAIMABLE =     0 KB
[over_bground_thresh]: wakeup flush-8:0 : BDI_RECLAIMABLE = 92032 KB
[over_bground_thresh]: wakeup flush-8:0 : BDI_RECLAIMABLE = 91968 KB
[over_bground_thresh]: wakeup flush-8:16 : BDI_RECLAIMABLE =   192 KB
[over_bground_thresh]: wakeup flush-8:16 : BDI_RECLAIMABLE =  1024 KB
[over_bground_thresh]: wakeup flush-8:16 : BDI_RECLAIMABLE =    64 KB
[over_bground_thresh]: wakeup flush-8:16 : BDI_RECLAIMABLE =   192 KB
[over_bground_thresh]: wakeup flush-8:16 : BDI_RECLAIMABLE =   576 KB
[over_bground_thresh]: wakeup flush-8:16 : BDI_RECLAIMABLE =     0 KB
[over_bground_thresh]: wakeup flush-8:0 : BDI_RECLAIMABLE = 84352 KB
[over_bground_thresh]: wakeup flush-8:16 : BDI_RECLAIMABLE =   192 KB
[over_bground_thresh]: wakeup flush-8:16 : BDI_RECLAIMABLE =   512 KB
[over_bground_thresh]: wakeup flush-8:16 : BDI_RECLAIMABLE =     0 KB
[over_bground_thresh]: wakeup flush-8:0 : BDI_RECLAIMABLE = 92608 KB
[over_bground_thresh]: wakeup flush-8:0 : BDI_RECLAIMABLE = 92544 KB

As mentioned in above log, when global dirty memory > global background_thresh
small cached data is also forced to flush by flush-8:16.
If removing global background_thresh checking code, we can reduce cache
thrashing of frequently used small data.
And It will be great if we can reserve a portion of writeback cache using
min_ratio.

After applying patch:
$ echo 5 > /sys/block/sdb/bdi/min_ratio
$ cat /sys/block/sdb/bdi/min_ratio
5
[over_bground_thresh]: wakeup flush-8:0 : BDI_RECLAIMABLE =  56064 KB
[over_bground_thresh]: wakeup flush-8:0 : BDI_RECLAIMABLE =  56704 KB
[over_bground_thresh]: wakeup flush-8:0 : BDI_RECLAIMABLE =  84160 KB
[over_bground_thresh]: wakeup flush-8:0 : BDI_RECLAIMABLE =  96960 KB
[over_bground_thresh]: wakeup flush-8:0 : BDI_RECLAIMABLE =  94080 KB
[over_bground_thresh]: wakeup flush-8:0 : BDI_RECLAIMABLE =  93120 KB
[over_bground_thresh]: wakeup flush-8:0 : BDI_RECLAIMABLE =  93120 KB
[over_bground_thresh]: wakeup flush-8:0 : BDI_RECLAIMABLE =  91520 KB
[over_bground_thresh]: wakeup flush-8:0 : BDI_RECLAIMABLE =  89600 KB
[over_bground_thresh]: wakeup flush-8:0 : BDI_RECLAIMABLE =  93696 KB
[over_bground_thresh]: wakeup flush-8:0 : BDI_RECLAIMABLE =  93696 KB
[over_bground_thresh]: wakeup flush-8:0 : BDI_RECLAIMABLE =  72960 KB
[over_bground_thresh]: wakeup flush-8:0 : BDI_RECLAIMABLE =  90624 KB
[over_bground_thresh]: wakeup flush-8:0 : BDI_RECLAIMABLE =  90624 KB
[over_bground_thresh]: wakeup flush-8:0 : BDI_RECLAIMABLE =  90688 KB

As mentioned in the above logs, once cache is reserved for Process B,
and patch is applied there is less writeback cache thrashing on sdb
by frequent forced writeback by flush-8:16 in over_bground_thresh.

After all, small cached data will be flushed by periodic writeback
once every dirty_writeback_interval.

Suggested-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Vivek Trivedi <t.vivek@samsung.com>
Signed-off-by: Francisco Franco <franciscofranco.1990@gmail.com>
writeback: increase bdi_min_ratio to 5 in light of the latest writeback commit.

Signed-off-by: Francisco Franco <franciscofranco.1990@gmail.com>
writeback: I believe these defines were calculated with HZ=1000 in mind. Since our devices are HZ=100 I hardcoded the values on this constants. I'm not 100% sure if this code was made for HZ with 1000 but I couldn't track it to understand clearly. Although I didn't see any drawback of using this as it is now. If anyone knows the answer please chime in.

Signed-off-by: Francisco Franco <franciscofranco.1990@gmail.com>
cpufreq: Retain only online cpus in managed_policy->cpus

cpufreq's handling of cpu online event can incorrectly initialize
managed_policy->cpus to include offline cpus. This causes cpufreq
governors to include offline cpus in their idle time computation, which
causes frequency to shoot up beyond normal levels (on systems where 2 or
more cpus need to be synchronized wrt frequency change).

This frequency shootup was not seen prior to commit 21111be8 which
changed idle time accounting for offline cpus. Prior to commit 21111be8,
idle time statistics for offline cpus would include their offline time
as well. Post commit 21111be8, offline time is not included in a cpu's
idle time statistics.

As a result, ondemand (or other cpufreq) governors would see unchanged
idle time for offline cpus, causing them to interpret those (offline)
cpus as 100% busy, which is wrong.

This patch fixes the issue by modifying cpufreq's hotplug handling to
retain only online cpus in managed_policy->cpus field. cpufreq governors
would then skip such offline cpus from idle time calculations.

Change-Id: Id2eba8c0ec3367609369b2e42a4e1386ff2e7ab5
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>
Signed-off-by: Francisco Franco <franciscofranco.1990@gmail.com>
msm: rpm-smd: Configure WQ for higer priority

When the workqueue runs at a lower priority, it gets starved by higher
priority threads. Bump the WQ priority to high to ensure rpm smd work
queue gets a fair chance

Change-Id: I06b864611cf45afe6931d6030327806032894663
Signed-off-by: Mahesh Sivasubramanian <msivasub@codeaurora.org>
Signed-off-by: Francisco Franco <franciscofranco.1990@gmail.com>
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: Francisco Franco <franciscofranco.1990@gmail.com>
lib: vsprintf.c: stash vsprintf.c commits from upstream.

Signed-off-by: Francisco Franco <franciscofranco.1990@gmail.com>
freezer: add unsafe versions of freezable helpers for CIFS

CIFS calls wait_event_freezekillable_unsafe with a VFS lock held,
which is unsafe and will cause lockdep warnings when 6aa9707
"lockdep: check that no locks held at freeze time" is reapplied
(it was reverted in dbf520a).  CIFS shouldn't be doing this, but
it has long-running syscalls that must hold a lock but also
shouldn't block suspend.  Until CIFS freeze handling is rewritten
to use a signal to exit out of the critical section, add a new
wait_event_freezekillable_unsafe helper that will not run the
lockdep test when 6aa9707 is reapplied, and call it from CIFS.

In practice the likley result of holding the lock while freezing
is that a second task blocked on the lock will never freeze,
aborting suspend, but it is possible to manufacture a case using
the cgroup freezer, the lock, and the suspend freezer to create
a deadlock.  Silencing the lockdep warning here will allow
problems to be found in other drivers that may have a more
serious deadlock risk, and prevent new problems from being added.

Acked-by: Pavel Machek <pavel@ucw.cz>
Acked-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Colin Cross <ccross@android.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Francisco Franco <franciscofranco.1990@gmail.com>
lockdep: remove task argument from debug_check_no_locks_held

The only existing caller to debug_check_no_locks_held calls it
with 'current' as the task, and the freezer needs to call
debug_check_no_locks_held but doesn't already have a current
task pointer, so remove the argument.  It is already assuming
that the current task is relevant by dumping the current stack
trace as part of the warning.

This was originally part of 6aa9707099c (lockdep: check that
no locks held at freeze time) which was reverted in
dbf520a9d7d4.

Original-author: Mandeep Singh Baines <msb@chromium.org>
Acked-by: Pavel Machek <pavel@ucw.cz>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Colin Cross <ccross@android.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Francisco Franco <franciscofranco.1990@gmail.com>
lockdep: check that no locks held at freeze time

We shouldn't try_to_freeze if locks are held.  Holding a lock can cause a
deadlock if the lock is later acquired in the suspend or hibernate path
(e.g.  by dpm).  Holding a lock can also cause a deadlock in the case of
cgroup_freezer if a lock is held inside a frozen cgroup that is later
acquired by a process outside that group.

History:
This patch was originally applied as 6aa9707099c and reverted in
dbf520a9d7d4 because NFS was freezing with locks held.  It was
deemed better to keep the bad freeze point in NFS to allow laptops
to suspend consistently.  The previous patch in this series converts
NFS to call _unsafe versions of the freezable helpers so that
lockdep doesn't complain about them until a more correct fix
can be applied.

[akpm@linux-foundation.org: export debug_check_no_locks_held]
Signed-off-by: Mandeep Singh Baines <msb@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Pavel Machek <pavel@ucw.cz>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Colin Cross <ccross@android.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Signed-off-by: Francisco Franco <franciscofranco.1990@gmail.com>

Conflicts:

	include/linux/freezer.h
Revert "lockdep: check that no locks held at freeze time"

This reverts commit 07535788e0b50da198376358982e4c9ecbea8b89.
freezer: skip waking up tasks with PF_FREEZER_SKIP set

Android goes through suspend/resume very often (every few seconds when
on a busy wifi network with the screen off), and a significant portion
of the energy used to go in and out of suspend is spent in the
freezer.  If a task has called freezer_do_not_count(), don't bother
waking it up.  If it happens to wake up later it will call
freezer_count() and immediately enter the refrigerator.

Combined with patches to convert freezable helpers to use
freezer_do_not_count() and convert common sites where idle userspace
tasks are blocked to use the freezable helpers, this reduces the
time and energy required to suspend and resume.

Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Colin Cross <ccross@android.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Francisco Franco <franciscofranco.1990@gmail.com>
freezer: convert freezable helpers to freezer_do_not_count()

Freezing tasks will wake up almost every userspace task from
where it is blocking and force it to run until it hits a
call to try_to_sleep(), generally on the exit path from the syscall
it is blocking in.  On resume each task will run again, usually
restarting the syscall and running until it hits the same
blocking call as it was originally blocked in.

Convert the existing wait_event_freezable* wrappers to use
freezer_do_not_count().  Combined with a previous patch,
these tasks will not run during suspend or resume unless they wake
up for another reason, in which case they will run until they hit
the try_to_freeze() in freezer_count(), and then continue processing
the wakeup after tasks are thawed.

This results in a small change in behavior, previously a race
between freezing and a normal wakeup would be won by the wakeup,
now the task will freeze and then handle the wakeup after thawing.

Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Colin Cross <ccross@android.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Francisco Franco <franciscofranco.1990@gmail.com>
freezer: convert freezable helpers to static inline where possible

Some of the freezable helpers have to be macros because their
condition argument needs to get evaluated every time through
the wait loop.  Convert the others to static inline to make
future changes easier.

Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Colin Cross <ccross@android.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Francisco Franco <franciscofranco.1990@gmail.com>

Conflicts:

	include/linux/freezer.h
Revert "freezer: convert freezable helpers to static inline where possible"

This reverts commit 786a2716570d7436b2a7035f238ef0a4bd26e4de.
freezer: add new freezable helpers using freezer_do_not_count()

Freezing tasks will wake up almost every userspace task from
where it is blocking and force it to run until it hits a
call to try_to_sleep(), generally on the exit path from the syscall
it is blocking in.  On resume each task will run again, usually
restarting the syscall and running until it hits the same
blocking call as it was originally blocked in.

To allow tasks to avoid running on every suspend/resume cycle,
this patch adds additional freezable wrappers around blocking calls
that call freezer_do_not_count().  Combined with the previous patch,
these tasks will not run during suspend or resume unless they wake
up for another reason, in which case they will run until they hit
the try_to_freeze() in freezer_count(), and then continue processing
the wakeup after tasks are thawed.

Additional patches will convert the most common locations that
userspace blocks in to use freezable helpers.

Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Colin Cross <ccross@android.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Francisco Franco <franciscofranco.1990@gmail.com>

Conflicts:

	include/linux/freezer.h
Revert "freezer: add new freezable helpers using freezer_do_not_count()"

This reverts commit 71712fd44f0c7c8fa9c0323744b5d5c9479892ba.