While working on the new version of the code for SCHED_SPORADIC I
noticed something strange in the present throttling mechanism. More
specifically in the throttling timer handler in sched_rt.c
(do_sched_rt_period_timer()) and in rt_rq_enqueue().

The problem is that, when unthrottling a runqueue, rt_rq_enqueue() only
asks for rescheduling if the runqueue has a sched_entity associated to
it (i.e., rt_rq->rt_se != NULL).
Now, if the runqueue is the root rq (which has a rt_se = NULL)
rescheduling does not take place, and it is delayed to some undefined
instant in the future.

This imply some random bandwidth usage by the RT tasks under throttling.
For instance, setting rt_runtime_us/rt_period_us = 950ms/1000ms an RT
task will get less than 95%. In our tests we got something varying
between 70% to 95%.
Using smaller time values, e.g., 95ms/100ms, things are even worse, and
I can see values also going down to 20-25%!!

The tests we performed are simply running 'yes' as a SCHED_FIFO task,
and checking the CPU usage with top, but we can investigate thoroughly
if you think it is needed.

Things go much better, for us, with the attached patch... Don't know if
it is the best approach, but it solved the issue for us.
Signed-off-by: Dario Faggioli <raistlin@linux.it>
Signed-off-by: Michael Trimarchi <trimarchimichael@yahoo.it>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: <stable@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

This patch does following:
o Removes unused variable and argument "rq".
o Optimizes one of the "if" conditions in wake_affine() - i.e.  if
  "balanced" is true, we need not do rest of the calculations in the
  condition.
o If this cpu is same as the previous cpu (on which woken up task
  was running when it went to sleep), no need to call wake_affine at all.
Signed-off-by: Amit K Arora <aarora@linux.vnet.ibm.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

cfs_rq->tasks list is used by the load balancer to iterate
over all the tasks. Currently it holds all the entities
(both task and group entities) because of which there is
a need to check for group entities explicitly during load
balancing. This patch changes the cfs_rq->tasks list to
hold only task entities.
Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

We should set the buddy even though we might already have the
TIF_RESCHED flag set.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

While playing around with it, I noticed we missed some sanity checks.
Also add some comments while we're there.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Hopefully clarify some of this code a little.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

We should not only correct the increment for the initial group, but should
be consistent and do so for all the groups we encounter.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Rework the wakeup preemption to work on real runtime instead of
the virtual runtime. This greatly simplifies the code.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

The documentation about the CFS scheduler is scarse when it comes to
scheduling policies. This patch adds a chapter about the scheduling
policies it supports. Peter Zijlstra provided most of the information
for it in

http://marc.info/?l=linux-kernel&m=122210038326356&w=2Signed-off-by: Martin Steigerwald <ms@teamix.de>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

- Add some comments to try to make the ifdef puzzle a bit clearer

- Explicitly inline one of the three init_hrtick() implementations.
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

LD      kernel/built-in.o
WARNING: kernel/built-in.o(.text+0x326): Section mismatch in reference
from the function init_hrtick() to the variable
.cpuinit.data:hotplug_hrtick_nb.8
The function init_hrtick() references
the variable __cpuinitdata hotplug_hrtick_nb.8.
This is often because init_hrtick lacks a __cpuinitdata
annotation or the annotation of hotplug_hrtick_nb.8 is wrong.
Signed-off-by: Md.Rakib H. Mullick <rakib.mullick@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

load_balance_fair() calls rcu_read_lock() but then traverses the list
 using the regular list traversal routine.  This patch converts the
list traversal to use the _rcu version.
Signed-off-by: Chris Friesen <cfriesen@nortel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

PCMCIA abuses dev->private_data in the probe methods. Unfortunately it
continues to abuse it after calling drv->probe() which leads to crashes and
other nasties (such as bogus probes of multifunction devices) giving errors like

pcmcia: registering new device pcmcia0.1
kernel: 0.1: GetNextTuple: No more items

Extract the passed data before calling the driver probe function that way
we don't blow up when the driver reuses dev->private_data as its right.

As its close to the final release just move the hack so it works out,
hopefully someone will be sufficiently embarrassed to produce a nice rework
for 2.6.28.
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input:
  Input: jornada720_ts - fix build error ( LONG() usage )
  Input: bcm5974 - switch back to normal mode when closing

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6:
  netdev: simple_tx_hash shouldn't hash inside fragments

WAKEUP_OVERLAP is not a winner on a 16way box, running psql+sysbench:

       .27-rc7-NO_WAKEUP_OVERLAP  .27-rc7-WAKEUP_OVERLAP
-------------------------------------------------
    1:             694              811    +14.39%
    2:            1454             1427    -1.86%
    4:            3017             3070    +1.70%
    8:            5694             5808    +1.96%
   16:           10592            10612    +0.19%
   32:            9693             9647    -0.48%
   64:            8507             8262    -2.97%
  128:            8402             7087    -18.55%
  256:            8419             5124    -64.30%
  512:            7990             3671    -117.62%
-------------------------------------------------
  SUM:           64466            55524    -16.11%

... so turn it off by default.
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Lin Ming reported a 10% OLTP regression against 2.6.27-rc4.

The difference seems to come from different preemption agressiveness,
which affects the cache footprint of the workload and its effective
cache trashing.

Aggresively preempt a task if its avg overlap is very small, this should
avoid the task going to sleep and find it still running when we schedule
back to it - saving a wakeup.
Reported-by: Lin Ming <ming.m.lin@intel.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

* 'hwmon-for-linus' of git://jdelvare.pck.nerim.net/jdelvare-2.6:
  hwmon: (ad7414) Make ad7414_update_device() static
  hwmon: (it87) Fix fan tachometer reading in IT8712F rev 0x7 (I)
  hwmon: (atxp1) Fix device detection logic

* 'kvm-updates/2.6.27' of git://git.kernel.org/pub/scm/linux/kernel/git/avi/kvm:
  KVM: ia64: 'struct fdesc' build fix

* 'upstream' of git://ftp.linux-mips.org/pub/scm/upstream-linus:
  [MIPS] vmlinux.lds.S: handle .text.*
  [MIPS] Fix potential latency problem due to non-atomic cpu_wait.
  [MIPS] SMTC: Clear TIF_FPUBOUND on clone / fork.
  [MIPS] Fix 64-bit IP checksum code

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/drzeus/mmc:
  mmc_test: initialize mmc_test_lock statically
  mmc_block: handle error from mmc_register_driver()
  atmel-mci: Set MMC_CAP_NEEDS_POLL if no detect_pin
  atmel-mci: Fix bogus debugfs file size
  atmel-mci: Fix memory leak in atmci_regs_show
  atmel-mci: debugfs: enable clock before dumping regs
  tmio_mmc: fix compilation with debug enabled

* Normalize some S: entries to match the enumeration at the beginning
  of the file.
* Change one mailing list entry from S: to L:.
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

* Drop trailing whitespace.
* Replace spaces and combinations of spaces and tabs by single tabs.
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The -ffunction-sections puts each text in .text.function_name section.
Without this patch, most functions are placed outside _text..._etext
area and it breaks show_stacktrace(), etc.
Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

If an interrupt happened between checking of NEED_RESCHED and WAIT
instruction, adjust EPC to restart from checking of NEED_RESCHED.
Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

Use unsigned loads to avoid possible misscalculation of IP checksums.  This
bug was instruced in f761106cd728bcf65b7fe161b10221ee00cf7132 (lmo) /
ed99e2bc (kernel.org).

[Original fix by Atsushi.  Improved instruction scheduling and fix for
unaligned unsigned load by me -- Ralf]
Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

Currently simple_tx_hash is hashing inside of udp fragments.  As a result
packets are getting getting sent to all queues when they shouldn't be.
This causes a serious performance regression which can be seen by sending
UDP frames larger than mtu on multiqueue devices.  This change will make
it so that fragments are hashed only as IP datagrams w/o any protocol
information.
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

The mutex mmc_test_lock is initialized at every time mmc_test device
is probed. Probing another mmc_test device may break the mutex, if
the probe function is called while the mutex is locked.

This patch fixes it by statically initializing mmc_test_lock.
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>

Check error from mmc_register_driver() and properly unwind
block device registration.
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>

This allows the mmc core to detect card insertion/removal for slots that
don't have any CD pin wired up.
Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>
Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>

We used to store a binary register snapshot in the "regs" file, so we
set the file size to be the size of this snapshot. This is no longer
valid since we switched to using seq_file.
Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>
Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>

The debugfs hook atmci_regs_show allocates a temporary buffer for
storing a register snapshot, but it doesn't free it before returning.
Plug this leak.
Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>
Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>

Make sure that the peripheral clock is enabled before reading the MMIO
registers for the debugfs "regs" dump.
Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>
Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>

Signed-off-by: Dmitry Baryshkov <dbaryshkov@gmail.com>
Acked-by: Ian Molton <spyro@f2s.com>
Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>

This patch makes the needlessly global ad7414_update_device() static.
Signed-off-by: Adrian Bunk <bunk@kernel.org>
Acked-by: Sean MacLennan <smaclennan@pikatech.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>

The IT8712F v0.9.1 datasheet applies to revisions >= 0x8 (J).
The driver was incorrectly attempting to enable 16-bit fan
readings on rev 0x7 (I) which led to incorrect RPM values.
Signed-off-by: Andrew Paprocki <andrew@ishiboo.com>
Tested-by: John Gumb <john.gumb@tandberg.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>

The atxp1 device detection code has a major logic flaw, fix it. Not
sure how we managed to miss this when the driver was merged...
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Acked-by: Sebastian Witt <se.witt@gmx.net>