AIO: Don't plug the I/O queue in do_io_submit() Asynchronous I/O latency to a solid-state disk greatly increased between the 2.6.32 and 3.0 kernels. By removing the plug from do_io_submit(), we observed a 34% improvement in the I/O latency.

Unfortunately, at this level, we don't know if the request is to
a rotating disk or not.

Change-Id: I7101df956473ed9fd5dcff18e473dd93b688a5c1
Signed-off-by: Dave Kleikamp <dave.kleikamp@oracle.com>
Cc: linux-aio@kvack.org
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jeff Moyer <jmoyer@redhat.com>
epoll: optimize EPOLL_CTL_DEL using rcu

Date	Tue, 1 Oct 2013 17:08:10 +0000 (GMT)

Optimize EPOLL_CTL_DEL such that it does not require the 'epmutex' by
converting the file->f_ep_links list into an rcu one. In this way, we can
traverse the epoll network on the add path in parallel with deletes. Since
deletes can't create loops or worse wakeup paths, this is safe.

This patch in combination with the patch "epoll: Do not take global 'epmutex'
for simple topologies", shows a dramatic performance improvement in
scalability for SPECjbb.

Tested-by: Nathan Zimmer <nzimmer@sgi.com>
Signed-off-by: Jason Baron <jbaron@akamai.com>

backported for Linux 3.4 for use on Android
Signed-off-by: Paul Reioux <reioux@gmail.com>
epoll: Do not take global 'epmutex' for simple topologies

Date	Tue, 1 Oct 2013 17:08:14 +0000 (GMT)

When calling EPOLL_CTL_ADD for an epoll file descriptor that is attached
directly to a wakeup source, we do not need to take the global 'epmutex',
unless the epoll file descriptor is nested. The purpose of taking
the 'epmutex' on add is to prevent complex topologies such as loops and
deep wakeup paths from forming in parallel through multiple EPOLL_CTL_ADD
operations. However, for the simple case of an epoll file descriptor
attached directly to a wakeup source (with no nesting), we do not need
to hold the 'epmutex'.

This patch along with 'epoll: optimize EPOLL_CTL_DEL using rcu' improves
scalability on larger systems. Quoting Nathan Zimmer's mail on SPECjbb
performance:

"
On the 16 socket run the performance went from 35k jOPS to 125k jOPS.
In addition the benchmark when from scaling well on 10 sockets to scaling well
on just over 40 sockets.

...

Currently the benchmark stops scaling at around 40-44 sockets but it seems like
I found a second unrelated bottleneck.
"

Tested-by: Nathan Zimmer <nzimmer@sgi.com>
Signed-off-by: Jason Baron <jbaron@akamai.com>

backported to Linux 3.4 for use on Android
Signed-off-by: Paul Reioux <reioux@gmail.com>
epoll: do not take globals epmutex for simple topologies fix

- use `bool' for boolean variables
- remove unneeded/undesirable cast of void*
- add missed ep_scan_ready_list() kerneldoc

Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Davide Libenzi <davidel@xmailserver.org>
Cc: Eric Wong <normalperson@yhbt.net>
Cc: Jason Baron <jbaron@akamai.com>
Cc: Nathan Zimmer <nzimmer@sgi.com>
Cc: Nelson Elhage <nelhage@nelhage.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Signed-off-by: Paul Reioux <reioux@gmail.com>
msm: watchdog: Add reboot/shutdown notifications to watchdog

On shutdown or reboot path, callee CPU waits for one second
in order for other CPUs to respond. However, this coincides
with watchdog pet to bark timeout value, which sometimes
results in unnecessary watchdog barks.

Since we are either shutting down or rebooting the machine
anyways, we might as well wait a bit longer for bark timeout.
This gives a better chance to a graceful shutdown or reboot the
system because their call-sites are race prone.

Change-Id: Ie82f16dcc7671ddc05bf6c6ea20aa71981607273
Signed-off-by: Jay Chokshi <jchokshi@codeaurora.org>
Signed-off-by: Ajay Dudani <adudani@codeaurora.org>
msm: timer: Don't check state of clock while setting next timer event

The commit fd6681cd4d0782f6e6ac918ab337016f59c2520b introduced
a silent bug that incorrectly checks state of the clock while
setting the next timer event. The bug manifests only during
failure code path of msm idle operation, which is very rare.
Due to the bug, the driver isn't be able to reprogram the timer
device.

CRs-fixed: 468902
Change-Id: I4ec14ea9c3a5d318ef98d2b13bd55efd89538df5
Signed-off-by: Jay Chokshi <jchokshi@codeaurora.org>
Signed-off-by: Ajay Dudani <adudani@codeaurora.org>
msm: mdm2: Decrease leakage before QSC power-up

Cleanup of IPC gpios for driver strength and toggle
AP2MDM_STATUS only after AP2MDM_KPD_PWR is toggled, this
will decrease the leakage from MSM to QSC before QSC
powering up.

CRs-Fixed: 460500
Change-Id: Iabfa34331b613dd66577e485572a809440cf5272
Signed-off-by: Taniya Das <tdas@codeaurora.org>

modified for Mako use

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