1. 17 May, 2008 3 commits
    • Thomas Gleixner's avatar
      x86: disable mwait for AMD family 10H/11H CPUs · e9623b35
      Thomas Gleixner authored
      The previous revert of 0c07ee38 left
      out the mwait disable condition for AMD family 10H/11H CPUs.
      
      Andreas Herrman said:
      
      It depends on the CPU. For AMD CPUs that support MWAIT this is wrong.
      Family 0x10 and 0x11 CPUs will enter C1 on HLT. Powersavings then
      depend on a clock divisor and current Pstate of the core.
      
      If all cores of a processor are in halt state (C1) the processor can
      enter the C1E (C1 enhanced) state. If mwait is used this will never
      happen.
      
      Thus HLT saves more power than MWAIT here.
      
      It might be best to switch off the mwait flag for these AMD CPU
      families like it was introduced with commit
      f039b754 (x86: Don't use MWAIT on AMD
      Family 10)
      
      Re-add the AMD families 10H/11H check and disable the mwait usage for
      those.
      Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
      e9623b35
    • Avi Kivity's avatar
      x86: fix crash on cpu hotplug on pat-incapable machines · 31f4d870
      Avi Kivity authored
      pat_disable() is __init, which means it goes away after booting is complete.
      Unfortunately it is used by the hotplug code if the machine is not
      pat-capable, causing a crash.
      
      Fix by marking pat_disable() as __cpuinit.
      Signed-off-by: default avatarAvi Kivity <avi@qumranet.com>
      Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      31f4d870
    • Ingo Molnar's avatar
      x86: remove mwait capability C-state check · a738d897
      Ingo Molnar authored
      Vegard Nossum reports:
      
      | powertop shows between 200-400 wakeups/second with the description
      | "<kernel IPI>: Rescheduling interrupts" when all processors have load (e.g.
      | I need to run two busy-loops on my 2-CPU system for this to show up).
      |
      | The bisect resulted in this commit:
      |
      | commit 0c07ee38
      | Date:   Wed Jan 30 13:33:16 2008 +0100
      |
      |     x86: use the correct cpuid method to detect MWAIT support for C states
      
      remove the functional effects of this patch and make mwait unconditional.
      
      A future patch will turn off mwait on specific CPUs where that causes
      power to be wasted.
      Bisected-by: default avatarVegard Nossum <vegard.nossum@gmail.com>
      Tested-by: default avatarVegard Nossum <vegard.nossum@gmail.com>
      Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      a738d897
  2. 16 May, 2008 5 commits
  3. 15 May, 2008 32 commits