mm: writeback: every 500ms the writeback daemon kicks in and flushes the dirty pages into disk. Thats not very pleasant for performance and *maybe* battery. This patch disables the writeback function while the screen is on, and enables it back when the screen is off to flush all the dirty pages. In my real world usage testing I notice a slight bump in smoothness and performance while using the device. (franciscofranco)
Reduce wakelock timeout (faster sleep)
sched: LOAD_FREQ (4*HZ+61) avoids loadavg Moire (by faux123)
net/ipv4: Eliminate kstrdup memory leak
percpu: zero memory more efficiently in mm/percpu.c::pcpu_mem_alloc()

Don't do vmalloc() + memset() when vzalloc() will do.

tj: dropped unnecessary temp variable ptr.

Signed-off-by: Jesper Juhl <jj@chaosbits.net>
Signed-off-by: Tejun Heo <tj@kernel.org>
shmem: reduce pagefault lock contention

I'm running a shmem pagefault test case (see attached file) under a 64 CPU
system.  Profile shows shmem_inode_info->lock is heavily contented and
100% CPUs time are trying to get the lock.  In the pagefault (no swap)
case, shmem_getpage gets the lock twice, the last one is avoidable if we
prealloc a page so we could reduce one time of locking.  This is what
below patch does.

The result of the test case:
2.6.35-rc3: ~20s
2.6.35-rc3 + patch: ~12s
so this is 40% improvement.

One might argue if we could have better locking for shmem.  But even shmem
is lockless, the pagefault will soon have pagecache lock heavily contented
because shmem must add new page to pagecache.  So before we have better
locking for pagecache, improving shmem locking doesn't have too much
improvement.  I did a similar pagefault test against a ramfs file, the
test result is ~10.5s.

[akpm@linux-foundation.org: fix comment, clean up code layout, elimintate code duplication]
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: "Zhang, Yanmin" <yanmin.zhang@intel.com>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
rwsem-spinlock: let rwsem write lock stealable

We(Linux Kernel Performance project) found a regression introduced by
commit 5a50508, which just convert all mutex lock to rwsem write lock.
The semantics is same, but the results is quite huge in some cases.
After investigation, we found the root cause: mutex support lock
stealing. Here is the link for the detailed regression report:
    https://lkml.org/lkml/2013/1/29/84

Ingo suggests to add write lock stealing to rwsem as well:
    "I think we should allow lock-steal between rwsem writers - that
     will not hurt fairness as most rwsem fairness concerns relate to
     reader vs. writer fairness"

And here is the rwsem-spinlock version.

With this patch, we got a double performance increase in one test box
with following aim7 workfile:
    FILESIZE: 1M
    POOLSIZE: 10M
    10 fork_test

some /usr/bin/time output w/o patch      some /usr/bin/time_output with patch
----------------------------------------------------------------------------
Percent of CPU this job got: 369%        Percent of CPU this job got: 537%
Voluntary context switches: 640595016    Voluntary context switches: 157915561
----------------------------------------------------------------------------
You will see we got a 45% increase of CPU usage and saves about 3/4
voluntary context switches.
Here is the .nr_running filed for all CPUs from /proc/sched_debug.

output w/o this patch:
----------------------
cpu 00:   0   0   ...   0   0   0   0   0   0   0   1   0   1 .... 0   0
cpu 01:   0   0   ...   1   0   0   0   0   0   1   1   0   1 .... 0   0
cpu 02:   0   0   ...   1   1   0   0   0   1   0   0   1   0 .... 1   1
cpu 03:   0   0   ...   0   1   0   0   0   1   1   0   1   1 .... 0   0
cpu 04:   0   1   ...   0   0   2   1   1   2   1   0   1   0 .... 1   0
cpu 05:   0   1   ...   0   0   2   1   1   2   1   1   1   1 .... 0   0
cpu 06:   0   0   ...   2   0   0   1   0   0   1   0   0   0 .... 0   0
cpu 07:   0   0   ...   2   0   0   0   1   0   1   1   0   0 .... 1   0
cpu 08:   0   0   ...   1   0   0   0   1   0   0   1   0   0 .... 0   1
cpu 09:   0   0   ...   1   0   0   0   1   0   0   1   0   0 .... 0   1
cpu 10:   0   0   ...   0   0   0   2   0   0   1   0   1   1 .... 1   2
cpu 11:   0   0   ...   0   0   0   2   2   0   1   0   1   0 .... 1   2
cpu 12:   0   0   ...   2   0   0   0   1   1   3   1   1   1 .... 1   0
cpu 13:   0   0   ...   2   0   0   0   1   1   3   1   1   0 .... 1   1
cpu 14:   0   0   ...   0   0   0   2   0   0   1   1   0   0 .... 1   0
cpu 15:   0   0   ...   1   0   0   2   0   0   1   1   0   0 .... 0   0
output with this patch:
-----------------------
cpu 00:   0   0   ...   1   1   2   1   1   1   2   1   1   1 .... 1   3
cpu 01:   0   0   ...   1   1   1   1   1   1   2   1   1   1 .... 1   3
cpu 02:   0   0   ...   2   2   3   2   0   2   1   2   1   1 .... 1   1
cpu 03:   0   0   ...   2   2   3   2   1   2   1   2   1   1 .... 1   1
cpu 04:   0   1   ...   2   0   0   1   0   1   3   1   1   1 .... 1   1
cpu 05:   0   1   ...   2   0   1   1   0   1   2   1   1   1 .... 1   1
cpu 06:   0   0   ...   2   1   1   2   0   1   2   1   1   1 .... 2   1
cpu 07:   0   0   ...   2   1   1   2   0   1   2   1   1   1 .... 2   1
cpu 08:   0   0   ...   1   1   1   1   1   1   1   1   1   1 .... 0   0
cpu 09:   0   0   ...   1   1   1   1   1   1   1   1   1   1 .... 0   0
cpu 10:   0   0   ...   1   1   1   0   0   1   1   1   1   1 .... 0   0
cpu 11:   0   0   ...   1   1   1   0   0   1   1   1   1   2 .... 1   0
cpu 12:   0   0   ...   1   1   1   0   1   1   0   0   0   1 .... 2   1
cpu 13:   0   0   ...   1   1   1   0   1   1   1   0   1   2 .... 2   0
cpu 14:   0   0   ...   2   0   0   0   0   1   1   1   1   1 .... 2   2
cpu 15:   0   0   ...   2   0   0   1   0   1   1   1   1   1 .... 2   2
------------------------------------------------------------------------
Where you can see that CPU is much busier with this patch.
v2: make it stealable at __down_write_trylock as well, pointed by Michel

Reported-by: LKP project <lkp@linux.intel.com>
Suggested-by: Ingo Molnar <mingo@kernel.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Michel Lespinasse <walken@google.com>
Signed-off-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
backported for Grouper Kernel from LKML reference

Signed-off-by: faux123 <reioux@gmail.com>
staging: framebuffer port from 3.0.8
init: calibrate: Backported from 3.0 kernel.
net sched: fix some kernel memory leaks
posix-timers: RCU conversion

    Ben Nagy reported a scalability problem with KVM/QEMU that hit very hard
    a single spinlock (idr_lock) in posix-timers code, on its 48 core
    machine.

    Even on a 16 cpu machine (2x4x2), a single test can show 98% of cpu time
    used in ticket_spin_lock, from lock_timer

    Ref: http://www.spinics.net/lists/kvm/msg51526.html

    Switching to RCU is quite easy, IDR being already RCU ready. idr_lock
    should be locked only for an insert/delete, not a lookup.

    Benchmark on a 2x4x2 machine, 16 processes calling timer_gettime().

    Before :

    real    1m18.669s
    user    0m1.346s
    sys     1m17.180s

    After :

    real    0m3.296s
    user    0m1.366s
    sys     0m1.926s

    Reported-by: Ben Nagy <ben@iagu.net>
    Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
    Tested-by: Ben Nagy <ben@iagu.net>
    Cc: Oleg Nesterov <oleg@redhat.com>
    Cc: Avi Kivity <avi@redhat.com>
    Cc: John Stultz <johnstul@us.ibm.com>
    Cc: Richard Cochran <richard.cochran@omicron.at>
    Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
    Cc: Andrew Morton <akpm@linux-foundation.org>
    Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

    Conflicts:

    	include/linux/posix-timers.h
msm: memory: Use standard cache routines
Convert custom clean, flush, and invalidate cache routines to use
standard ARM cache routines.

Change-Id: Ida0c539b89e1b6c98542221f847a9bcd7fc32a2e
Signed-off-by: Olav Haugan <ohaugan@codeaurora.org>
(cherry picked from commit 29bb4d5)

Signed-off-by: Zhoulu Luo <zluo@codeaurora.org>

Conflicts:
	arch/arm/mach-msm/memory.c
lib: Improve the performance of memcpy and memmove of the general version

The performance of memcpy and memmove of the general version is
very inefficient, this patch improves them.
kernel: Prevent unnecessary rfkill event generation.

Prevent unnecessary rfkill event generation when the state has
not actually changed. These events have to be delivered to
relevant userspace processes, causing these processes to wake
up and do something while they could as well have slept. This
obviously results in more CPU usage, longer time-to-sleep-again
and therefore higher power consumption.

Change-Id: I3ac4e141fbdf1315b74d3bad6aa96f34b00c3f92
CRs-fixed: 398283
Signed-off-by: Vitaly Wool <vitalywool@gmail.com>
Signed-off-by: Mykyta Iziumtsev <nikita.izyumtsev@gmail.com>
Signed-off-by: Deepthi Gowri <deepthi@codeaurora.org>
Added optimized CRC32 algorithm (Ezekeel)
cgroup: speed up access to cgroupfs mounted entries in /proc/mounts
Revert "lib: Improve the performance of memcpy and memmove of the general version"

This reverts commit 18d9e062ce2e4ee501db2772f8b233377f3a0ad9.