mm: optmize SLUB
Makefile: add optmization levels
ksm: Provide support to use deferred timers for scanner
 thread

KSM thread to scan pages is getting schedule on definite timeout.
That wakes up CPU from idle state and hence may affect the power
consumption. Provide an optional support to use deferred timer
which suites low-power use-cases.

To enable deferred timers,
$ echo 1 > /sys/kernel/mm/ksm/deferred_timer

Change-Id: I07fe199f97fe1f72f9a9e1b0b757a3ac533719e8
Signed-off-by: Chintan Pandya <cpandya@codeaurora.org>
block: recursive merge requests

In a workload, thread 1 accesses a, a+2, ..., thread 2 accesses a+1, a+3,....
When the requests are flushed to queue, a and a+1 are merged to (a, a+1), a+2
and a+3 too to (a+2, a+3), but (a, a+1) and (a+2, a+3) aren't merged.

If we do recursive merge for such interleave access, some workloads throughput
get improvement. A recent worload I'm checking on is swap, below change
boostes the throughput around 5% ~ 10%.

Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Francisco Franco <franciscofranco.1990@gmail.com>
fs/sync: Make sync() satisfy many requests with one invocation

Dave Jones reported RCU stalls, overly long hrtimer interrupts, and
amazingly long NMI handlers from a trinity-induced workload involving
lots of concurrent sync() calls (https://lkml.org/lkml/2013/7/23/369).
There are any number of things that one might do to make sync() behave
better under high levels of contention, but it is also the case that
multiple concurrent sync() system calls can be satisfied by a single
sys_sync() invocation.

Given that this situation is reminiscent of rcu_barrier(), this commit
applies the rcu_barrier() approach to sys_sync().  This approach uses
a global mutex and a sequence counter.  The mutex is held across the
sync() operation, which eliminates contention between concurrent sync()
operations.  The counter is incremented at the beginning and end of
each sync() operation, so that it is odd while a sync() operation is in
progress and even otherwise, just like sequence locks.

The code that used to be in sys_sync() is now in do_sync(), and sys_sync()
now handles the concurrency.  The sys_sync() function first takes a
snapshot of the counter, then acquires the mutex, and then takes another
snapshot of the counter.  If the values of the two snapshots indicate that
a full do_sync() executed during the mutex acquisition, the sys_sync()
function releases the mutex and returns ("Our work is done!").  Otherwise,
sys_sync() increments the counter, invokes do_sync(), and increments
the counter again.

This approach allows a single call to do_sync() to satisfy an arbitrarily
large number of sync() system calls, which should eliminate issues due
to large numbers of concurrent invocations of the sync() system call.

Changes since v1 (https://lkml.org/lkml/2013/7/24/683):

o	Add a pair of memory barriers to keep the increments from
	bleeding into the do_sync() code.  (The failure probability
	is insanely low, but when you have several hundred million
	devices running Linux, you can expect several hundred instances
	of one-in-a-million failures.)

o	Actually CC some people who have experience in this area.

Reported-by: Dave Jones <davej@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Jan Kara <jack@suse.cz>
Cc: Curt Wohlgemuth <curtw@google.com>
Cc: Jens Axboe <jaxboe@fusionio.com>
Cc: linux-fsdevel@vger.kernel.org

Signed-off-by: Paul Reioux <reioux@gmail.com>
fs/dcache.c: Fix the too small buffer for dname

temp[64] is used for internal temporary buffer in dynamic_dname().
This is for dname. But It's too small. dname's size may be > 64.
In that case, it returns as -ENAMETOOLONG. So Increase the buffer size
to 256 for avoiding this issue.

The following was caused by the small buffer.
WARNING: at /kernel/mm/page_alloc.c:2470 __alloc_pages_nodemask+0x24c/0x938()
CPU: 2 PID: 505 Comm: android.bg Not tainted 3.10.0-g2f73780-00003-g2ff41d9-dirty #13
[<c010ba3c>] (unwind_backtrace+0x0/0x11c) from [<c0109cac>] (show_stack+0x10/0x14)
[<c0109cac>] (show_stack+0x10/0x14) from [<c01939a0>] (warn_slowpath_common+0x48/0x68)
[<c01939a0>] (warn_slowpath_common+0x48/0x68) from [<c0193a7c>] (warn_slowpath_null+0x18/0x20)
[<c0193a7c>] (warn_slowpath_null+0x18/0x20) from [<c0222454>] (__alloc_pages_nodemask+0x24c/0x938)
[<c0222454>] (__alloc_pages_nodemask+0x24c/0x938) from [<c0222b50>] (__get_free_pages+0x10/0x24)
[<c0222b50>] (__get_free_pages+0x10/0x24) from [<c024faf8>] (kmalloc_order_trace+0x24/0xf0)
[<c024faf8>] (kmalloc_order_trace+0x24/0xf0) from [<c024fe20>] (__kmalloc+0x30/0x244)
[<c024fe20>] (__kmalloc+0x30/0x244) from [<c02723c8>] (seq_read+0x270/0x464)
[<c02723c8>] (seq_read+0x270/0x464) from [<c0256a18>] (vfs_read+0xa4/0x134)
[<c0256a18>] (vfs_read+0xa4/0x134) from [<c0256de8>] (SyS_read+0x38/0x68)
[<c0256de8>] (SyS_read+0x38/0x68) from [<c0106140>] (ret_fast_syscall+0x0/0x30)

Change-Id: I74f5217ba3c4be73e91f33f900f1f0c26810cc05
Signed-off-by: Devin Kim <dojip.kim@lge.com>
Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>
Logger: Add sysfs interface to Enable / Disable Android Logger
printk: Add sys kernel interface to configure linux printk logging
- now logging can be switched on and off via /sys/kernel/printk_mode interface
- default is 1 (on)
- Enabled time stamp information in logs again
Commit by andip71
https://github.com/gustavoss/android_kernel_samsung_smdk4412/commit/f5eab64ee388080525699e84de1e5da653e241bc
initramfs: preparations for synapse support