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  1. 25 6月, 2009 1 次提交
    • R
      MIPS: Add arch generic CPU hotplug · 1b2bc75c
      由 Ralf Baechle 提交于 
      Each platform has to add support for CPU hotplugging itself by providing
suitable definitions for the cpu_disable and cpu_die of the smp_ops
methods and setting SYS_SUPPORTS_HOTPLUG_CPU.  A platform should only set
SYS_SUPPORTS_HOTPLUG_CPU once all it's smp_ops definitions have the
necessary changes.  This patch contains the changes to the dummy smp_ops
definition for uni-processor systems.

Parts of the code contributed by Cavium Inc.
Signed-off-by: NRalf Baechle <ralf@linux-mips.org>
      1b2bc75c
  3. 03 4月, 2009 1 次提交
  5. 04 10月, 2008 1 次提交
  7. 21 9月, 2008 1 次提交
  9. 07 9月, 2008 1 次提交
  11. 19 7月, 2008 1 次提交
    • T
      nohz: prevent tick stop outside of the idle loop · b8f8c3cf
      由 Thomas Gleixner 提交于 
      Jack Ren and Eric Miao tracked down the following long standing
problem in the NOHZ code:

	scheduler switch to idle task
	enable interrupts

Window starts here

	----> interrupt happens (does not set NEED_RESCHED)
	      	irq_exit() stops the tick

	----> interrupt happens (does set NEED_RESCHED)

	return from schedule()
	
	cpu_idle(): preempt_disable();

Window ends here

The interrupts can happen at any point inside the race window. The
first interrupt stops the tick, the second one causes the scheduler to
rerun and switch away from idle again and we end up with the tick
disabled.

The fact that it needs two interrupts where the first one does not set
NEED_RESCHED and the second one does made the bug obscure and extremly
hard to reproduce and analyse. Kudos to Jack and Eric.

Solution: Limit the NOHZ functionality to the idle loop to make sure
that we can not run into such a situation ever again.

cpu_idle()
{
	preempt_disable();

	while(1) {
		 tick_nohz_stop_sched_tick(1); <- tell NOHZ code that we
		 			          are in the idle loop

		 while (!need_resched())
		       halt();

		 tick_nohz_restart_sched_tick(); <- disables NOHZ mode
		 preempt_enable_no_resched();
		 schedule();
		 preempt_disable();
	}
}

In hindsight we should have done this forever, but ... 

/me grabs a large brown paperbag.

Debugged-by: Jack Ren <jack.ren@marvell.com>, 
Debugged-by: Neric miao <eric.y.miao@gmail.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
      b8f8c3cf
  13. 16 7月, 2008 1 次提交
  15. 15 12月, 2007 1 次提交
  17. 12 10月, 2007 3 次提交
  19. 01 8月, 2007 1 次提交
  21. 21 7月, 2007 1 次提交
  23. 11 7月, 2007 1 次提交
  25. 27 2月, 2007 1 次提交
  27. 19 2月, 2007 2 次提交
  29. 07 2月, 2007 1 次提交
  31. 20 10月, 2006 1 次提交
  33. 10 10月, 2006 1 次提交
  35. 02 10月, 2006 2 次提交
  37. 27 9月, 2006 8 次提交
  39. 01 7月, 2006 1 次提交
  41. 19 4月, 2006 2 次提交
  43. 01 4月, 2006 1 次提交
  45. 21 3月, 2006 1 次提交
  47. 15 2月, 2006 1 次提交
  49. 09 2月, 2006 2 次提交
  51. 13 1月, 2006 2 次提交