linux.git/kernel/sched, branch v3.6-rc2

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

2012-08-03T17:58:13+00:00

Pull scheduler fixes from Ingo Molnar:
 "Fixes and two late cleanups"

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/cleanups: Add load balance cpumask pointer to 'struct lb_env'
  sched: Fix comment about PREEMPT_ACTIVE bit location
  sched: Fix minor code style issues
  sched: Use task_rq_unlock() in __sched_setscheduler()
  sched/numa: Add SD_PERFER_SIBLING to CPU domain

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

2012-07-31T22:34:13+00:00

Pull perf updates from Ingo Molnar:
 "The biggest changes are Intel Nehalem-EX PMU uncore support, uprobes
  updates/cleanups/fixes from Oleg and diverse tooling updates (mostly
  fixes) now that Arnaldo is back from vacation."

* 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (40 commits)
  uprobes: __replace_page() needs munlock_vma_page()
  uprobes: Rename vma_address() and make it return "unsigned long"
  uprobes: Fix register_for_each_vma()->vma_address() check
  uprobes: Introduce vaddr_to_offset(vma, vaddr)
  uprobes: Teach build_probe_list() to consider the range
  uprobes: Remove insert_vm_struct()->uprobe_mmap()
  uprobes: Remove copy_vma()->uprobe_mmap()
  uprobes: Fix overflow in vma_address()/find_active_uprobe()
  uprobes: Suppress uprobe_munmap() from mmput()
  uprobes: Uprobe_mmap/munmap needs list_for_each_entry_safe()
  uprobes: Clean up and document write_opcode()->lock_page(old_page)
  uprobes: Kill write_opcode()->lock_page(new_page)
  uprobes: __replace_page() should not use page_address_in_vma()
  uprobes: Don't recheck vma/f_mapping in write_opcode()
  perf/x86: Fix missing struct before structure name
  perf/x86: Fix format definition of SNB-EP uncore QPI box
  perf/x86: Make bitfield unsigned
  perf/x86: Fix LLC-* and node-* events on Intel SandyBridge
  perf/x86: Add Intel Nehalem-EX uncore support
  perf/x86: Fix typo in format definition of uncore PCU filter
  ...

sched/cleanups: Add load balance cpumask pointer to 'struct lb_env'

2012-07-31T15:00:16+00:00

With this patch struct ld_env will have a pointer of the load balancing
cpumask and we don't need to pass a cpumask around anymore.

Signed-off-by: Michael Wang 
Signed-off-by: Peter Zijlstra 
Link: http://lkml.kernel.org/r/4FFE8665.3080705@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar

sched: Deliver sched_switch events to the current task

2012-07-26T10:23:10+00:00

Otherwise they can't be filtered for a defined task:

  perf record -e sched:sched_switch ./foo

This command doesn't report any events without this patch.

I think it isn't a security concern if someone knows who will
be executed next - this can already be observed by polling /proc
state. By default perf is disabled for non-root users in any case.

I need these events for profiling sleep times.  sched_switch is used for
getting callchains and sched_stat_* is used for getting time periods.
These events are combined in user space, then it can be analyzed by
perf tools.

Signed-off-by: Andrew Vagin 
Signed-off-by: Peter Zijlstra 
Cc: Steven Rostedt 
Cc: Arun Sharma 
Link: http://lkml.kernel.org/r/1342088069-1005148-1-git-send-email-avagin@openvz.org
Signed-off-by: Ingo Molnar

sched: Fix minor code style issues

2012-07-26T09:47:00+00:00

Delete redudant spaces between type name and data name or operators.

Signed-off-by: Ying Xue 
Signed-off-by: Peter Zijlstra 
Link: http://lkml.kernel.org/r/1342076622-6606-1-git-send-email-ying.xue0@gmail.com
Signed-off-by: Ingo Molnar

sched: Use task_rq_unlock() in __sched_setscheduler()

2012-07-26T09:46:59+00:00

It seems there's no specific reason to open-code it.  I guess
commit 0122ec5b02f76 ("sched: Add p->pi_lock to task_rq_lock()")
simply missed it.  Let's be consistent with others.

Signed-off-by: Namhyung Kim 
Signed-off-by: Peter Zijlstra 
Link: http://lkml.kernel.org/r/1341647342-6742-1-git-send-email-namhyung@kernel.org
Signed-off-by: Ingo Molnar

sched: Fix race in task_group()

2012-07-24T11:58:20+00:00

Stefan reported a crash on a kernel before a3e5d1091c1 ("sched:
Don't call task_group() too many times in set_task_rq()"), he
found the reason to be that the multiple task_group()
invocations in set_task_rq() returned different values.

Looking at all that I found a lack of serialization and plain
wrong comments.

The below tries to fix it using an extra pointer which is
updated under the appropriate scheduler locks. Its not pretty,
but I can't really see another way given how all the cgroup
stuff works.

Reported-and-tested-by: Stefan Bader 
Signed-off-by: Peter Zijlstra 
Link: http://lkml.kernel.org/r/1340364965.18025.71.camel@twins
Signed-off-by: Ingo Molnar

sched: Improve balance_cpu() to consider other cpus in its group as target of (pinned) task

2012-07-24T11:58:06+00:00

Current load balance scheme requires only one cpu in a
sched_group (balance_cpu) to look at other peer sched_groups for
imbalance and pull tasks towards itself from a busy cpu. Tasks
thus pulled by balance_cpu could later get picked up by cpus
that are in the same sched_group as that of balance_cpu.

This scheme however fails to pull tasks that are not allowed to
run on balance_cpu (but are allowed to run on other cpus in its
sched_group). That can affect fairness and in some worst case
scenarios cause starvation.

Consider a two core (2 threads/core) system running tasks as
below:

          Core0            Core1
         /     \          /     \
	C0     C1	 C2     C3
        |      |         |      |
        v      v         v      v
	F0     T1        F1     [idle]
			 T2

 F0 = SCHED_FIFO task (pinned to C0)
 F1 = SCHED_FIFO task (pinned to C2)
 T1 = SCHED_OTHER task (pinned to C1)
 T2 = SCHED_OTHER task (pinned to C1 and C2)

F1 could become a cpu hog, which will starve T2 unless C1 pulls
it. Between C0 and C1 however, C0 is required to look for
imbalance between cores, which will fail to pull T2 towards
Core0. T2 will starve eternally in this case. The same scenario
can arise in presence of non-rt tasks as well (say we replace F1
with high irq load).

We tackle this problem by having balance_cpu move pinned tasks
to one of its sibling cpus (where they can run). We first check
if load balance goal can be met by ignoring pinned tasks,
failing which we retry move_tasks() with a new env->dst_cpu.

This patch modifies load balance semantics on who can move load
towards a given cpu in a given sched_domain.

Before this patch, a given_cpu or a ilb_cpu acting on behalf of
an idle given_cpu is responsible for moving load to given_cpu.

With this patch applied, balance_cpu can in addition decide on
moving some load to a given_cpu.

There is a remote possibility that excess load could get moved
as a result of this (balance_cpu and given_cpu/ilb_cpu deciding
*independently* and at *same* time to move some load to a
given_cpu). However we should see less of such conflicting
decisions in practice and moreover subsequent load balance
cycles should correct the excess load moved to given_cpu.

Signed-off-by: Srivatsa Vaddagiri 
Signed-off-by: Prashanth Nageshappa 
Signed-off-by: Peter Zijlstra 
Link: http://lkml.kernel.org/r/4FE06CDB.2060605@linux.vnet.ibm.com
[ minor edits ]
Signed-off-by: Ingo Molnar

sched: Reset loop counters if all tasks are pinned and we need to redo load balance

2012-07-24T11:55:37+00:00

While load balancing, if all tasks on the source runqueue are pinned,
we retry after excluding the corresponding source cpu. However, loop counters
env.loop and env.loop_break are not reset before retrying, which can lead
to failure in moving the tasks. In this patch we reset env.loop and
env.loop_break to their inital values before we retry.

Signed-off-by: Prashanth Nageshappa 
Signed-off-by: Peter Zijlstra 
Link: http://lkml.kernel.org/r/4FE06EEF.2090709@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar

sched: Reorder 'struct lb_env' members to reduce its size

2012-07-24T11:55:20+00:00

Members of 'struct lb_env' are not in appropriate order to reuse compiler
added padding on 64bit architectures. In this patch we reorder those struct
members and help reduce the size of the structure from 96 bytes to 80
bytes on 64 bit architectures.

Suggested-by: Srivatsa Vaddagiri 
Signed-off-by: Prashanth Nageshappa 
Signed-off-by: Peter Zijlstra 
Link: http://lkml.kernel.org/r/4FE06DDE.7000403@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar