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  1. 11 Nov, 2010 1 commit
  3. 10 Nov, 2010 2 commits
    • Peter Zijlstra's avatar
      sched: Fix runnable condition for stoptask · 2d467090
      Peter Zijlstra authored 
      Heiko reported that the TASK_RUNNING check is not sufficient for
CONFIG_PREEMPT=y since we can get preempted with !TASK_RUNNING.

He suggested adding a ->se.on_rq test to the existing TASK_RUNNING
one, however TASK_RUNNING will always have ->se.on_rq, so we might as
well reduce that to a single test.

[ stop tasks should never get preempted, but its good to handle
  this case correctly should this ever happen ]
Reported-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      2d467090
    • Suresh Siddha's avatar
      sched: Use group weight, idle cpu metrics to fix imbalances during idle · aae6d3dd
      Suresh Siddha authored 
      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: default avatarNikhil Rao <ncrao@google.com>
Signed-off-by: default avatarSuresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1284760952.2676.11.camel@sbsiddha-MOBL3.sc.intel.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      aae6d3dd
  5. 09 Nov, 2010 5 commits
  7. 08 Nov, 2010 17 commits
  9. 06 Nov, 2010 7 commits
  11. 05 Nov, 2010 8 commits
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