linux.git/Documentation, branch v3.0-rc4

Merge branch 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

2011-06-19T15:56:56+00:00

* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  rcu: Move RCU_BOOST #ifdefs to header file
  rcu: use softirq instead of kthreads except when RCU_BOOST=y
  rcu: Use softirq to address performance regression
  rcu: Simplify curing of load woes

Documentation: fix cgroup typos and formatting

2011-06-16T04:52:50+00:00

Fix format and spelling.

Signed-off-by: Jörg Sommer 
Acked-by: Paul Menage 
Signed-off-by: Randy Dunlap 
Signed-off-by: Linus Torvalds

Documentation: update cgroupfs mount point

2011-06-16T04:52:50+00:00

According to commit 676db4af0430 ("cgroupfs: create /sys/fs/cgroup to
mount cgroupfs on") the canonical mountpoint for the cgroup filesystem
is /sys/fs/cgroup.  Hence, this should be used in the documentation.

Signed-off-by: Jörg Sommer 
Acked-by: Paul Menage 
Signed-off-by: Randy Dunlap 
Signed-off-by: Linus Torvalds

Documentation: update kmemleak supported archs

2011-06-16T04:52:50+00:00

Instead of listing the architectures that are supported by
kmemleak in Documentation/kmemleak.txt, just refer people to
the list of supported architecutures in lib/Kconfig.debug so
that Documentation/kmemleak.txt does not need more updates
for this.

Signed-off-by: Maxin B. John 
Signed-off-by: Randy Dunlap 
Signed-off-by: Linus Torvalds

Documentation: update printk-formats.txt

2011-06-16T04:52:50+00:00

This patch updates the incomplete documentation concerning the printk
extended format specifiers.

Signed-off-by: Andrew Murray 
Signed-off-by: Randy Dunlap 
Signed-off-by: Linus Torvalds

Documentation/feature-removal-schedule.txt: remove ns_cgroup from feature-removal-schedule.txt

2011-06-16T03:04:02+00:00

Commit a77aea92010acf ("cgroup: remove the ns_cgroup") removed the
ns_cgroup but it forgot to remove the related doc in
feature-removal-schedule.txt.

Signed-off-by: WANG Cong 
Cc: Daniel Lezcano 
Cc: Serge E.  Hallyn 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

memcg: add documentation for the memory.numastat API

2011-06-16T03:03:59+00:00

[akpm@linux-foundation.org: rework text, fit it into 80-cols]
Signed-off-by: Ying Han 
Reviewed-by: KOSAKI Motohiro 
Acked-by: Balbir Singh 
Acked-by: KAMEZAWA Hiroyuki 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

backlight: new driver for the ADP8870 backlight devices

2011-06-16T03:03:59+00:00

Signed-off-by: Michael Hennerich 
Signed-off-by: Mike Frysinger 
Cc: Richard Purdie 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

rcu: Use softirq to address performance regression

2011-06-14T22:25:39+00:00

Commit a26ac2455ffcf3(rcu: move TREE_RCU from softirq to kthread)
introduced performance regression. In an AIM7 test, this commit degraded
performance by about 40%.

The commit runs rcu callbacks in a kthread instead of softirq. We observed
high rate of context switch which is caused by this. Out test system has
64 CPUs and HZ is 1000, so we saw more than 64k context switch per second
which is caused by RCU's per-CPU kthread.  A trace showed that most of
the time the RCU per-CPU kthread doesn't actually handle any callbacks,
but instead just does a very small amount of work handling grace periods.
This means that RCU's per-CPU kthreads are making the scheduler do quite
a bit of work in order to allow a very small amount of RCU-related
processing to be done.

Alex Shi's analysis determined that this slowdown is due to lock
contention within the scheduler.  Unfortunately, as Peter Zijlstra points
out, the scheduler's real-time semantics require global action, which
means that this contention is inherent in real-time scheduling.  (Yes,
perhaps someone will come up with a workaround -- otherwise, -rt is not
going to do well on large SMP systems -- but this patch will work around
this issue in the meantime.  And "the meantime" might well be forever.)

This patch therefore re-introduces softirq processing to RCU, but only
for core RCU work.  RCU callbacks are still executed in kthread context,
so that only a small amount of RCU work runs in softirq context in the
common case.  This should minimize ksoftirqd execution, allowing us to
skip boosting of ksoftirqd for CONFIG_RCU_BOOST=y kernels.

Signed-off-by: Shaohua Li 
Tested-by: "Alex,Shi" 
Signed-off-by: Paul E. McKenney

Merge branch 'for-linus' of git://neil.brown.name/md

2011-06-14T18:21:21+00:00

* 'for-linus' of git://neil.brown.name/md:
  md/raid5: remove unusual use of bio_iovec_idx()
  md/raid5: fix FUA request handling in ops_run_io()
  md/raid5: fix raid5_set_bi_hw_segments
  md:Documentation/md.txt - fix typo
  md/bitmap: remove unused fields from struct bitmap
  md/bitmap: use proper accessor macro
  md: check ->hot_remove_disk when removing disk
  md: Using poll  /proc/mdstat can monitor the events of adding a spare disks
  MD: use is_power_of_2 macro
  MD: raid5 do not set fullsync
  MD: support initial bitmap creation in-kernel
  MD: add sync_super to mddev_t struct
  MD: raid1 changes to allow use by device mapper
  MD: move thread wakeups into resume
  MD: possible typo
  MD: no sync IO while suspended
  MD: no integrity register if no gendisk