Messages in this thread | | | Date | Mon, 24 Mar 2008 11:57:38 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH 0/2] printk vs rq->lock and xtime lock |
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On Mon, 24 Mar 2008 19:15:47 +0100 Peter Zijlstra <a.p.zijlstra@chello.nl> wrote:
> How about I use the lockdep infrastructure to check if printk() is > invoked whole holding either xtime or rq lock, and then avoid calling > wake_up_klogd(). That way, we at least get sane debug output when the > lock debugging infrastructure is enabled?
The core problem seems to be that printk shouldn't be calling wake_up(). Can we fix that?
I expect it would be acceptable to do it from the timer interrupt instead. For NOHZ kernels a poll when we enter the idle loop would also be needed.
But does that cover everything? Is it possible for a CPU to run 100% busy while not receiving timer interrupts? I guess so. To receive no interrupts at all? Also possible.
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