STWEAKS: Advance Video Control
mm: implement WasActive page flag (for improving cleancache)
Since about 2.6.27, the page replacement algorithm maintains
an 'active' bit to help decide which pages are most eligible
to reclaim, see http://linux-mm.org/PageReplacementDesign

This 'active' information is also useful to cleancache but is lost
by the time that cleancache has the opportunity to preserve the
pageful of data.  This patch adds a new page flag 'WasActive' to
retain the state.  The flag may possibly be useful elsewhere.

It is up to each cleancache backend to utilize the bit as
it desires.  The matching patch for zcache is included here
for clarification/discussion purposes, though it will need to
go through GregKH and the staging tree.

The patch resolves issues reported with cleancache which occur
especially during streaming workloads on older processors,
see https://lkml.org/lkml/2011/8/17/351

Change-Id: Ib0b16a9c7d5278bd93d245fa6e2a986626b3938f

Conflicts:
	drivers/staging/zcache/zcache.c
	include/linux/page-flags.h
mm: implement WasActive page flag (for improving cleancache)
Since about 2.6.27, the page replacement algorithm maintains
an 'active' bit to help decide which pages are most eligible
to reclaim, see http://linux-mm.org/PageReplacementDesign

This 'active' information is also useful to cleancache but is lost
by the time that cleancache has the opportunity to preserve the
pageful of data.  This patch adds a new page flag 'WasActive' to
retain the state.  The flag may possibly be useful elsewhere.

It is up to each cleancache backend to utilize the bit as
it desires.  The matching patch for zcache is included here
for clarification/discussion purposes, though it will need to
go through GregKH and the staging tree.

The patch resolves issues reported with cleancache which occur
especially during streaming workloads on older processors,
see https://lkml.org/lkml/2011/8/17/351

Change-Id: Ib0b16a9c7d5278bd93d245fa6e2a986626b3938f

Conflicts:
	drivers/staging/zcache/zcache.c
	include/linux/page-flags.h
printk: add module parameter ignore_loglevel to control ignore_loglevel

We are enabling some power features on medfield.  To test suspend-2-RAM
conveniently, we need turn on/off ignore_loglevel frequently without
rebooting.

Add a module parameter, so users can change it by:
/sys/module/printk/parameters/ignore_loglevel

Signed-off-by: Yanmin Zhang <yanmin.zhang@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
printk: add console_suspend module parameter

We are enabling some power features on medfield.  To test suspend-2-RAM
conveniently, we need turn on/off console_suspend_enabled frequently.

Add a module parameter, so users could change it by:
/sys/module/printk/parameters/console_suspend

Signed-off-by: Yanmin Zhang <yanmin_zhang@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
printk: fix bounds checking for log_prefix

Currently log_prefix is testing that the first character of the log level
and facility is less than '0' and greater than '9' (which is always
false).  It should be testing to see if the character less than '0' or
greater than '9' instead.  This patch makes that change.

The code being changed worked because strtoul bombs out (endp isn't
updated) and 0 is returned anyway.

Signed-off-by: William Douglas <william.douglas@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
printk: remove bounds checking for log_prefix

Currently log_prefix is testing that the first character of the log level
and facility is less than '0' and greater than '9' (which is always
false).

Since the code being updated works because strtoul bombs out (endp isn't
updated) and 0 is returned anyway just remove the check and don't change
the behavior of the function.

Signed-off-by: William Douglas <william.douglas@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
sched: fix broken SCHED_RESET_ON_FORK handling

Setting child->prio = current->normal_prio _after_ SCHED_RESET_ON_FORK has
been handled for an RT parent gives birth to a deranged mutant child with
non-RT policy, but RT prio and sched_class.

Move PI leakage protection up, always set priorities and weight, and if the
child is leaving RT class, reset rt_priority to the proper value.

Signed-off-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1311779695.8691.2.camel@marge.simson.net
Signed-off-by: Ingo Molnar <mingo@elte.hu>
kernel/sysctl.c: add cap_last_cap to /proc/sys/kernel

Userspace needs to know the highest valid capability of the running
kernel, which right now cannot reliably be retrieved from the header files
only.  The fact that this value cannot be determined properly right now
creates various problems for libraries compiled on newer header files
which are run on older kernels.  They assume capabilities are available
which actually aren't.  libcap-ng is one example.  And we ran into the
same problem with systemd too.

Now the capability is exported in /proc/sys/kernel/cap_last_cap.

[akpm@linux-foundation.org: make cap_last_cap const, per Ulrich]
Signed-off-by: Dan Ballard <dan@mindstab.net>
Cc: Randy Dunlap <rdunlap@xenotime.net>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Lennart Poettering <lennart@poettering.net>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Cc: Ulrich Drepper <drepper@akkadia.org>
Cc: James Morris <jmorris@namei.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Conflicts:
	Documentation/sysctl/kernel.txt
	kernel/sysctl.c

Change-Id: I102161f7549c0f3042692d63ea3d708f5f47b828

Conflicts:
	kernel/sysctl.c
Cross Memory Attach

The basic idea behind cross memory attach is to allow MPI programs doing
intra-node communication to do a single copy of the message rather than a
double copy of the message via shared memory.

The following patch attempts to achieve this by allowing a destination
process, given an address and size from a source process, to copy memory
directly from the source process into its own address space via a system
call.  There is also a symmetrical ability to copy from the current
process's address space into a destination process's address space.

- Use of /proc/pid/mem has been considered, but there are issues with
  using it:
  - Does not allow for specifying iovecs for both src and dest, assuming
    preadv or pwritev was implemented either the area read from or
  written to would need to be contiguous.
  - Currently mem_read allows only processes who are currently
  ptrace'ing the target and are still able to ptrace the target to read
  from the target. This check could possibly be moved to the open call,
  but its not clear exactly what race this restriction is stopping
  (reason  appears to have been lost)
  - Having to send the fd of /proc/self/mem via SCM_RIGHTS on unix
  domain socket is a bit ugly from a userspace point of view,
  especially when you may have hundreds if not (eventually) thousands
  of processes  that all need to do this with each other
  - Doesn't allow for some future use of the interface we would like to
  consider adding in the future (see below)
  - Interestingly reading from /proc/pid/mem currently actually
  involves two copies! (But this could be fixed pretty easily)

As mentioned previously use of vmsplice instead was considered, but has
problems.  Since you need the reader and writer working co-operatively if
the pipe is not drained then you block.  Which requires some wrapping to
do non blocking on the send side or polling on the receive.  In all to all
communication it requires ordering otherwise you can deadlock.  And in the
example of many MPI tasks writing to one MPI task vmsplice serialises the
copying.

There are some cases of MPI collectives where even a single copy interface
does not get us the performance gain we could.  For example in an
MPI_Reduce rather than copy the data from the source we would like to
instead use it directly in a mathops (say the reduce is doing a sum) as
this would save us doing a copy.  We don't need to keep a copy of the data
from the source.  I haven't implemented this, but I think this interface
could in the future do all this through the use of the flags - eg could
specify the math operation and type and the kernel rather than just
copying the data would apply the specified operation between the source
and destination and store it in the destination.

Although we don't have a "second user" of the interface (though I've had
some nibbles from people who may be interested in using it for intra
process messaging which is not MPI).  This interface is something which
hardware vendors are already doing for their custom drivers to implement
fast local communication.  And so in addition to this being useful for
OpenMPI it would mean the driver maintainers don't have to fix things up
when the mm changes.

There was some discussion about how much faster a true zero copy would
go. Here's a link back to the email with some testing I did on that:

http://marc.info/?l=linux-mm&m=130105930902915&w=2

There is a basic man page for the proposed interface here:

http://ozlabs.org/~cyeoh/cma/process_vm_readv.txt

This has been implemented for x86 and powerpc, other architecture should
mainly (I think) just need to add syscall numbers for the process_vm_readv
and process_vm_writev. There are 32 bit compatibility versions for
64-bit kernels.

For arch maintainers there are some simple tests to be able to quickly
verify that the syscalls are working correctly here:

http://ozlabs.org/~cyeoh/cma/cma-test-20110718.tgz

Signed-off-by: Chris Yeoh <yeohc@au1.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: David Howells <dhowells@redhat.com>
Cc: James Morris <jmorris@namei.org>
Cc: <linux-man@vger.kernel.org>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Conflicts:
	arch/x86/include/asm/unistd_64.h
	fs/compat.c

Change-Id: I6a6db509d4048b131955ec492b52d4f3c628db48
sched: Don't update shares twice on on_rq parent

In dequeue_task_fair() we bail on dequeue when we encounter a parenting entity
with additional weight.  However, we perform a double shares update on this
entity as we continue the shares update traversal from this point, despite
dequeue_entity() having already updated its queuing cfs_rq.
Avoid this by starting from the parent when we resume.

Signed-off-by: Paul Turner <pjt@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20110707053059.797714697@google.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
sched: update correct entity's runtime in check_preempt_wakeup()

While looking at check_preempt_wakeup() I realized that we are
potentially updating the wrong entity in the fair-group scheduling
case. In this case the current task's cfs_rq may not be the same as
the one used for the comparison between the waking task and the
existing task's vruntime.

This potentially results in us using a stale vruntime in the
pre-emption decision, providing a small false preference for the
previous task. The effects of this are bounded since we always
perform a hierarchal update on the tick.

Signed-off-by: Paul Turner <pjt@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/CAPM31R+2Ke2urUZKao5W92_LupdR4AYEv-EZWiJ3tG=tEes2cw@mail.gmail.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
perf: Optimize ctx_sched_out()

Oleg noted that ctx_sched_out() disables the PMU even though it might
not actually do something, avoid needless PMU-disabling.

Reported-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20110409192141.665385503@chello.nl
Signed-off-by: Ingo Molnar <mingo@elte.hu>
perf: Clean up 'ctx' reference counting

Small cleanup to how we refcount in find_get_context(), this also
allows us to use put_ctx() to free things instead of using kfree().

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20110409192141.719340481@chello.nl
Signed-off-by: Ingo Molnar <mingo@elte.hu>
perf: Optimize event scheduling locking

Currently we only hold one ctx->lock at a time, which results in us
flipping back and forth between cpuctx->ctx.lock and task_ctx->lock.

Avoid this and gain large atomic regions by holding both locks. We
nest the task lock inside the cpu lock, since with task scheduling we
might have to change task ctx while holding the cpu ctx lock.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20110409192141.769881865@chello.nl
Signed-off-by: Ingo Molnar <mingo@elte.hu>
perf: Remove task_ctx_sched_in()

Make task_ctx_sched_*() imply EVENT_ALL, since anything less will not
actually have scheduled the task in/out at all.

Since there's no site that schedules all of a task in (due to the
interleave with flexible cpuctx) we can remove this function.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20110409192141.817893268@chello.nl
Signed-off-by: Ingo Molnar <mingo@elte.hu>
perf: Simplify and fix __perf_install_in_context()

Currently __perf_install_in_context() will try and schedule in the
event irrespective of our event scheduling rules, that is, we try to
schedule CPU-pinned, TASK-pinned, CPU-flexible, TASK-flexible, but
when creating a new event we simply try and schedule it on top of
whatever is already on the PMU, this can lead to errors for pinned
events.

Therefore, simplify things and simply schedule everything out, add the
event to the corresponding context and schedule everything back in.

This also nicely handles the case where with
__ARCH_WANT_INTERRUPTS_ON_CTXSW the IPI can come right in the middle
of schedule, before we managed to call perf_event_task_sched_in().

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20110409192141.870894224@chello.nl
Signed-off-by: Ingo Molnar <mingo@elte.hu>
perf: Change and simplify ctx::is_active semantics

Instead of tracking if a context is active or not, track which events
of the context are active. By making it a bitmask of
EVENT_PINNED|EVENT_FLEXIBLE we can simplify some of the scheduling
routines since it can avoid adding events that are already active.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20110409192141.930282378@chello.nl
Signed-off-by: Ingo Molnar <mingo@elte.hu>
perf: Collect the schedule-in rules in one function

This was scattered out - refactor it into a single function.
No change in functionality.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20110409192141.979862055@chello.nl
Signed-off-by: Ingo Molnar <mingo@elte.hu>
perf: Change close() semantics for group events

In order to always call list_del_event() on the correct cpu if the
event is part of an active context and avoid having to do two IPIs,
change the close() semantics slightly.

The current perf_event_disable() call would disable a whole group if
the event that's being closed is the group leader, whereas the new
code keeps the group siblings enabled.

People should not rely on this behaviour and I don't think they do,
but in case we find they do, the fix is easy and we have to take the
double IPI cost.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Vince Weaver <vweaver1@eecs.utk.edu>
Link: http://lkml.kernel.org/r/20110409192142.038377551@chello.nl
Signed-off-by: Ingo Molnar <mingo@elte.hu>