1. 20 8月, 2010 1 次提交
    • S
      x86, tsc, sched: Recompute cyc2ns_offset's during resume from sleep states · cd7240c0
      Suresh Siddha 提交于
      TSC's get reset after suspend/resume (even on cpu's with invariant TSC
      which runs at a constant rate across ACPI P-, C- and T-states). And in
      some systems BIOS seem to reinit TSC to arbitrary large value (still
      sync'd across cpu's) during resume.
      
      This leads to a scenario of scheduler rq->clock (sched_clock_cpu()) less
      than rq->age_stamp (introduced in 2.6.32). This leads to a big value
      returned by scale_rt_power() and the resulting big group power set by the
      update_group_power() is causing improper load balancing between busy and
      idle cpu's after suspend/resume.
      
      This resulted in multi-threaded workloads (like kernel-compilation) go
      slower after suspend/resume cycle on core i5 laptops.
      
      Fix this by recomputing cyc2ns_offset's during resume, so that
      sched_clock() continues from the point where it was left off during
      suspend.
      Reported-by: NFlorian Pritz <flo@xssn.at>
      Signed-off-by: NSuresh Siddha <suresh.b.siddha@intel.com>
      Cc: <stable@kernel.org> # [v2.6.32+]
      Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
      LKML-Reference: <1282262618.2675.24.camel@sbsiddha-MOBL3.sc.intel.com>
      Signed-off-by: NIngo Molnar <mingo@elte.hu>
      cd7240c0
  2. 19 8月, 2010 1 次提交
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