1. 07 12月, 2011 3 次提交
  2. 06 12月, 2011 8 次提交
  3. 17 11月, 2011 2 次提交
  4. 16 11月, 2011 3 次提交
  5. 14 11月, 2011 2 次提交
  6. 06 10月, 2011 3 次提交
    • P
      sched: Wrap scheduler p->cpus_allowed access · fa17b507
      Peter Zijlstra 提交于
      This task is preparatory for the migrate_disable() implementation, but
      stands on its own and provides a cleanup.
      
      It currently only converts those sites required for task-placement.
      Kosaki-san once mentioned replacing cpus_allowed with a proper
      cpumask_t instead of the NR_CPUS sized array it currently is, that
      would also require something like this.
      Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
      Acked-by: NThomas Gleixner <tglx@linutronix.de>
      Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Link: http://lkml.kernel.org/n/tip-e42skvaddos99psip0vce41o@git.kernel.orgSigned-off-by: NIngo Molnar <mingo@elte.hu>
      fa17b507
    • S
      sched: Request for idle balance during nohz idle load balance · 6eb57e0d
      Suresh Siddha 提交于
      rq's idle_at_tick is set to idle/busy during the timer tick
      depending on the cpu was idle or not. This will be used later in the load
      balance that will be done in the softirq context (which is a process
      context in -RT kernels).
      
      For nohz kernels, for the cpu doing nohz idle load balance on behalf of
      all the idle cpu's, its rq->idle_at_tick might have a stale value (which is
      recorded when it got the timer tick presumably when it is busy).
      
      As the nohz idle load balancing is also being done at the same place
      as the regular load balancing, nohz idle load balancing was bailing out
      when it sees rq's idle_at_tick not set.
      
      Thus leading to poor system utilization.
      
      Rename rq's idle_at_tick to idle_balance and set it when someone requests
      for nohz idle balance on an idle cpu.
      Reported-by: NSrivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
      Signed-off-by: NSuresh Siddha <suresh.b.siddha@intel.com>
      Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
      Link: http://lkml.kernel.org/r/20111003220934.892350549@sbsiddha-desk.sc.intel.comSigned-off-by: NIngo Molnar <mingo@elte.hu>
      6eb57e0d
    • S
      sched: Use resched IPI to kick off the nohz idle balance · ca38062e
      Suresh Siddha 提交于
      Current use of smp call function to kick the nohz idle balance can deadlock
      in this scenario.
      
      1. cpu-A did a generic_exec_single() to cpu-B and after queuing its call single
      data (csd) to the call single queue, cpu-A took a timer interrupt.  Actual IPI
      to cpu-B to process the call single queue is not yet sent.
      
      2. As part of the timer interrupt handler, cpu-A decided to kick cpu-B
      for the idle load balancing (sets cpu-B's rq->nohz_balance_kick to 1)
      and __smp_call_function_single() with nowait will queue the csd to the
      cpu-B's queue. But the generic_exec_single() won't send an IPI to cpu-B
      as the call single queue was not empty.
      
      3. cpu-A is busy with lot of interrupts
      
      4. Meanwhile cpu-B is entering and exiting idle and noticed that it has
      it's rq->nohz_balance_kick set to '1'. So it will go ahead and do the
      idle load balancer and clear its rq->nohz_balance_kick.
      
      5. At this point, csd queued as part of the step-2 above is still locked
      and waiting to be serviced on cpu-B.
      
      6. cpu-A is still busy with interrupt load and now it got another timer
      interrupt and as part of it decided to kick cpu-B for another idle load
      balancing (as it finds cpu-B's rq->nohz_balance_kick cleared in step-4
      above) and does __smp_call_function_single() with the same csd that is
      still locked.
      
      7. And we get a deadlock waiting for the csd_lock() in the
      __smp_call_function_single().
      
      Main issue here is that cpu-B can service the idle load balancer kick
      request from cpu-A even with out receiving the IPI and this lead to
      doing multiple __smp_call_function_single() on the same csd leading to
      deadlock.
      
      To kick a cpu, scheduler already has the reschedule vector reserved. Use
      that mechanism (kick_process()) instead of using the generic smp call function
      mechanism to kick off the nohz idle load balancing and avoid the deadlock.
      
         [ This issue is present from 2.6.35+ kernels, but marking it -stable
           only from v3.0+ as the proposed fix depends on the scheduler_ipi()
           that is introduced recently. ]
      Reported-by: NPrarit Bhargava <prarit@redhat.com>
      Signed-off-by: NSuresh Siddha <suresh.b.siddha@intel.com>
      Cc: stable@kernel.org # v3.0+
      Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
      Link: http://lkml.kernel.org/r/20111003220934.834943260@sbsiddha-desk.sc.intel.comSigned-off-by: NIngo Molnar <mingo@elte.hu>
      ca38062e
  7. 26 9月, 2011 1 次提交
  8. 14 8月, 2011 14 次提交
  9. 22 7月, 2011 4 次提交