1. 23 9月, 2008 1 次提交
    • T
      clockevents: prevent cpu online to interfere with nohz · 6441402b
      Thomas Gleixner 提交于
      Impact: rare hang which can be triggered on CPU online.
      
      tick_do_timer_cpu keeps track of the CPU which updates jiffies
      via do_timer. The value -1 is used to signal, that currently no
      CPU is doing this. There are two cases, where the variable can 
      have this state:
      
       boot:
          necessary for systems where the boot cpu id can be != 0
      
       nohz long idle sleep:
          When the CPU which did the jiffies update last goes into
          a long idle sleep it drops the update jiffies duty so
          another CPU which is not idle can pick it up and keep
          jiffies going.
      
      Using the same value for both situations is wrong, as the CPU online
      code can see the -1 state when the timer of the newly onlined CPU is
      setup. The setup for a newly onlined CPU goes through periodic mode
      and can pick up the do_timer duty without being aware of the nohz /
      highres mode of the already running system.
      
      Use two separate states and make them constants to avoid magic
      numbers confusion. 
      Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
      6441402b
  2. 22 9月, 2008 7 次提交
  3. 21 9月, 2008 4 次提交
  4. 20 9月, 2008 28 次提交