linux-stable.git/include/linux/sched.h, branch linux-2.6.37.y

sched: Cure more NO_HZ load average woes

2010-12-08T19:15:04+00:00

There's a long-running regression that proved difficult to fix and
which is hitting certain people and is rather annoying in its effects.

Damien reported that after 74f5187ac8 (sched: Cure load average vs
NO_HZ woes) his load average is unnaturally high, he also noted that
even with that patch reverted the load avgerage numbers are not
correct.

The problem is that the previous patch only solved half the NO_HZ
problem, it addressed the part of going into NO_HZ mode, not of
comming out of NO_HZ mode. This patch implements that missing half.

When comming out of NO_HZ mode there are two important things to take
care of:

 - Folding the pending idle delta into the global active count.
 - Correctly aging the averages for the idle-duration.

So with this patch the NO_HZ interaction should be complete and
behaviour between CONFIG_NO_HZ=[yn] should be equivalent.

Furthermore, this patch slightly changes the load average computation
by adding a rounding term to the fixed point multiplication.

Reported-by: Damien Wyart 
Reported-by: Tim McGrath 
Tested-by: Damien Wyart 
Tested-by: Orion Poplawski 
Tested-by: Kyle McMartin 
Signed-off-by: Peter Zijlstra 
Cc: stable@kernel.org
Cc: Chase Douglas 
LKML-Reference: <1291129145.32004.874.camel@laptop>
Signed-off-by: Ingo Molnar

sched: Use group weight, idle cpu metrics to fix imbalances during idle

2010-11-10T22:13:56+00:00

Currently we consider a sched domain to be well balanced when the imbalance
is less than the domain's imablance_pct. As the number of cores and threads
are increasing, current values of imbalance_pct (for example 25% for a
NUMA domain) are not enough to detect imbalances like:

a) On a WSM-EP system (two sockets, each having 6 cores and 12 logical threads),
24 cpu-hogging tasks get scheduled as 13 on one socket and 11 on another
socket. Leading to an idle HT cpu.

b) On a hypothetial 2 socket NHM-EX system (each socket having 8 cores and
16 logical threads), 16 cpu-hogging tasks can get scheduled as 9 on one
socket and 7 on another socket. Leaving one core in a socket idle
whereas in another socket we have a core having both its HT siblings busy.

While this issue can be fixed by decreasing the domain's imbalance_pct
(by making it a function of number of logical cpus in the domain), it
can potentially cause more task migrations across sched groups in an
overloaded case.

Fix this by using imbalance_pct only during newly_idle and busy
load balancing. And during idle load balancing, check if there
is an imbalance in number of idle cpu's across the busiest and this
sched_group or if the busiest group has more tasks than its weight that
the idle cpu in this_group can pull.

Reported-by: Nikhil Rao 
Signed-off-by: Suresh Siddha 
Signed-off-by: Peter Zijlstra 
LKML-Reference: <1284760952.2676.11.camel@sbsiddha-MOBL3.sc.intel.com>
Signed-off-by: Ingo Molnar

Merge branch 'for-linus' of git://git.infradead.org/users/eparis/notify

2010-10-30T18:50:37+00:00

* 'for-linus' of git://git.infradead.org/users/eparis/notify: (22 commits)
  Ensure FMODE_NONOTIFY is not set by userspace
  make fanotify_read() restartable across signals
  fsnotify: remove alignment padding from fsnotify_mark on 64 bit builds
  fs/notify/fanotify/fanotify_user.c: fix warnings
  fanotify: Fix FAN_CLOSE comments
  fanotify: do not recalculate the mask if the ignored mask changed
  fanotify: ignore events on directories unless specifically requested
  fsnotify: rename FS_IN_ISDIR to FS_ISDIR
  fanotify: do not send events for irregular files
  fanotify: limit number of listeners per user
  fanotify: allow userspace to override max marks
  fanotify: limit the number of marks in a single fanotify group
  fanotify: allow userspace to override max queue depth
  fsnotify: implement a default maximum queue depth
  fanotify: ignore fanotify ignore marks if open writers
  fanotify: allow userspace to flush all marks
  fsnotify: call fsnotify_parent in perm events
  fsnotify: correctly handle return codes from listeners
  fanotify: use __aligned_u64 in fanotify userspace metadata
  fanotify: implement fanotify listener ordering
  ...

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

2010-10-29T15:05:33+00:00

* 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  sched_stat: Update sched_info_queue/dequeue() code comments
  sched, cgroup: Fixup broken cgroup movement

fanotify: limit number of listeners per user

2010-10-28T21:22:15+00:00

fanotify currently has no limit on the number of listeners a given user can
have open.  This patch limits the total number of listeners per user to
128.  This is the same as the inotify default limit.

Signed-off-by: Eric Paris

signals: move cred_guard_mutex from task_struct to signal_struct

2010-10-28T01:03:12+00:00

Oleg Nesterov pointed out we have to prevent multiple-threads-inside-exec
itself and we can reuse ->cred_guard_mutex for it.  Yes, concurrent
execve() has no worth.

Let's move ->cred_guard_mutex from task_struct to signal_struct.  It
naturally prevent multiple-threads-inside-exec.

Signed-off-by: KOSAKI Motohiro 
Reviewed-by: Oleg Nesterov 
Acked-by: Roland McGrath 
Acked-by: David Howells 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

signals: annotate lock_task_sighand()

2010-10-28T01:03:12+00:00

lock_task_sighand() grabs sighand->siglock in case of returning non-NULL
but unlock_task_sighand() releases it unconditionally.  This leads sparse
to complain about the lock context imbalance.  Rename and wrap
lock_task_sighand() using __cond_lock() macro to make sparse happy.

Suggested-by: Eric Dumazet 
Signed-off-by: Namhyung Kim 
Cc: Ingo Molnar 
Cc: Oleg Nesterov 
Cc: Roland McGrath 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

kernel: remove PF_FLUSHER

2010-10-26T23:52:15+00:00

PF_FLUSHER is only ever set, not tested, remove it.

Signed-off-by: Peter Zijlstra 
Cc: Jens Axboe 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge branch 'for-2.6.37/core' of git://git.kernel.dk/linux-2.6-block

2010-10-23T00:00:32+00:00

* 'for-2.6.37/core' of git://git.kernel.dk/linux-2.6-block: (39 commits)
  cfq-iosched: Fix a gcc 4.5 warning and put some comments
  block: Turn bvec_k{un,}map_irq() into static inline functions
  block: fix accounting bug on cross partition merges
  block: Make the integrity mapped property a bio flag
  block: Fix double free in blk_integrity_unregister
  block: Ensure physical block size is unsigned int
  blkio-throttle: Fix possible multiplication overflow in iops calculations
  blkio-throttle: limit max iops value to UINT_MAX
  blkio-throttle: There is no need to convert jiffies to milli seconds
  blkio-throttle: Fix link failure failure on i386
  blkio: Recalculate the throttled bio dispatch time upon throttle limit change
  blkio: Add root group to td->tg_list
  blkio: deletion of a cgroup was causes oops
  blkio: Do not export throttle files if CONFIG_BLK_DEV_THROTTLING=n
  block: set the bounce_pfn to the actual DMA limit rather than to max memory
  block: revert bad fix for memory hotplug causing bounces
  Fix compile error in blk-exec.c for !CONFIG_DETECT_HUNG_TASK
  block: set the bounce_pfn to the actual DMA limit rather than to max memory
  block: Prevent hang_check firing during long I/O
  cfq: improve fsync performance for small files
  ...

Fix up trivial conflicts due to __rcu sparse annotation in include/linux/genhd.h

sched, cgroup: Fixup broken cgroup movement

2010-10-22T12:16:45+00:00

Dima noticed that we fail to correct the ->vruntime of sleeping tasks
when we move them between cgroups.

Reported-by: Dima Zavin 
Signed-off-by: Peter Zijlstra 
Tested-by: Mike Galbraith 
LKML-Reference: <1287150604.29097.1513.camel@twins>
Signed-off-by: Ingo Molnar