freezer: shorten freezer sleep time using exponential backoff

Date	Wed, 1 May 2013 18:34:59 -0700

All tasks can easily be frozen in under 10 ms, switch to using
an initial 1 ms sleep followed by exponential backoff until
8 ms.  Also convert the printed time to ms instead of centiseconds.

Signed-off-by: Colin Cross <ccross@android.com>
modified for Mako hybrid from LKML

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

Conflicts:
	kernel/power/process.c
Signed-off-by: zeroblade1984 <zeroblade1984@gmail.com>
freezer: skip waking up tasks with PF_FREEZER_SKIP set

Date	Wed, 1 May 2013 18:35:00 -0700

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.

Signed-off-by: Colin Cross <ccross@android.com>
Signed-off-by: zeroblade1984 <zeroblade1984@gmail.com>
freezer: add new freezable helpers using freezer_do_not_count()

Date	Wed, 1 May 2013 18:35:01 -0700

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.  This patch also converts the
existing wait_event_freezable* wrappers to use freezer_do_not_count().

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

Signed-off-by: Colin Cross <ccross@android.com>

Conflicts:
	include/linux/freezer.h
Signed-off-by: zeroblade1984 <zeroblade1984@gmail.com>
binder: use freezable blocking calls

Date	Wed, 1 May 2013 18:35:02 -0700

Avoid waking up every thread sleeping in a binder call during
suspend and resume by calling a freezable blocking call.  Previous
patches modified the freezer to avoid sending wakeups to threads
that are blocked in freezable blocking calls.

This call was selected to be converted to a freezable call because
it doesn't hold any locks or release any resources when interrupted
that might be needed by another freezing task or a kernel driver
during suspend, and is a common site where idle userspace tasks are
blocked.

Signed-off-by: Colin Cross <ccross@android.com>
Signed-off-by: zeroblade1984 <zeroblade1984@gmail.com>
epoll: use freezable blocking call

Date	Wed, 1 May 2013 18:35:03 -0700

Avoid waking up every thread sleeping in an epoll_wait call during
suspend and resume by calling a freezable blocking call.  Previous
patches modified the freezer to avoid sending wakeups to threads
that are blocked in freezable blocking calls.

This call was selected to be converted to a freezable call because
it doesn't hold any locks or release any resources when interrupted
that might be needed by another freezing task or a kernel driver
during suspend, and is a common site where idle userspace tasks are
blocked.

Signed-off-by: Colin Cross <ccross@android.com>
Signed-off-by: zeroblade1984 <zeroblade1984@gmail.com>
select: use freezable blocking call

Date	Wed, 1 May 2013 18:35:04 -0700

Avoid waking up every thread sleeping in a select call during
suspend and resume by calling a freezable blocking call.  Previous
patches modified the freezer to avoid sending wakeups to threads
that are blocked in freezable blocking calls.

This call was selected to be converted to a freezable call because
it doesn't hold any locks or release any resources when interrupted
that might be needed by another freezing task or a kernel driver
during suspend, and is a common site where idle userspace tasks are
blocked.

Signed-off-by: Colin Cross <ccross@android.com>
Signed-off-by: zeroblade1984 <zeroblade1984@gmail.com>
futex: use freezable blocking call

Date	Wed, 1 May 2013 18:35:05 -0700

Avoid waking up every thread sleeping in a futex_wait call during
suspend and resume by calling a freezable blocking call.  Previous
patches modified the freezer to avoid sending wakeups to threads
that are blocked in freezable blocking calls.

This call was selected to be converted to a freezable call because
it doesn't hold any locks or release any resources when interrupted
that might be needed by another freezing task or a kernel driver
during suspend, and is a common site where idle userspace tasks are
blocked.

Signed-off-by: Colin Cross <ccross@android.com>
Signed-off-by: zeroblade1984 <zeroblade1984@gmail.com>
nanosleep: use freezable blocking call

Date	Wed, 1 May 2013 18:35:06 -0700

Avoid waking up every thread sleeping in a nanosleep call during
suspend and resume by calling a freezable blocking call.  Previous
patches modified the freezer to avoid sending wakeups to threads
that are blocked in freezable blocking calls.

This call was selected to be converted to a freezable call because
it doesn't hold any locks or release any resources when interrupted
that might be needed by another freezing task or a kernel driver
during suspend, and is a common site where idle userspace tasks are
blocked.

Signed-off-by: Colin Cross <ccross@android.com>
Signed-off-by: zeroblade1984 <zeroblade1984@gmail.com>
sigtimedwait: use freezable blocking call

Date	Wed, 1 May 2013 18:35:07 -0700

Avoid waking up every thread sleeping in a sigtimedwait call during
suspend and resume by calling a freezable blocking call.  Previous
patches modified the freezer to avoid sending wakeups to threads
that are blocked in freezable blocking calls.

This call was selected to be converted to a freezable call because
it doesn't hold any locks or release any resources when interrupted
that might be needed by another freezing task or a kernel driver
during suspend, and is a common site where idle userspace tasks are
blocked.

Signed-off-by: Colin Cross <ccross@android.com>
Signed-off-by: zeroblade1984 <zeroblade1984@gmail.com>
af_unix: use freezable blocking calls in read

Date	Wed, 1 May 2013 18:35:08 -0700

Avoid waking up every thread sleeping in read call on an AF_UNIX
socket during suspend and resume by calling a freezable blocking
call.  Previous patches modified the freezer to avoid sending
wakeups to threads that are blocked in freezable blocking calls.

This call was selected to be converted to a freezable call because
it doesn't hold any locks or release any resources when interrupted
that might be needed by another freezing task or a kernel driver
during suspend, and is a common site where idle userspace tasks are
blocked.

Signed-off-by: Colin Cross <ccross@android.com>
Signed-off-by: zeroblade1984 <zeroblade1984@gmail.com>