Re: migration thread and active_load_balance

From: Dan Upton
Date: Sun Apr 20 2008 - 20:47:09 EST


> >
> > Anyway, like I said, I've spent several days trying to understand this
> > error by putting in printk()s galore and doing traces through the
>
> That might be obvious, but are you aware that printks inside
> the scheduler can lead to deadlocks? printk when the buffer
> is full calls wake_up and that calls the scheduler. So for
> debugging the scheduler you need some other way to get
> the information out.
>
> -Andi
>

Yes, I've read that printk can cause deadlocks, although I get the
deadlocks without printks as well. Also, I found a modification on
kerneltrap (http://kerneltrap.org/mailarchive/linux-kernel/2008/1/23/595569)
that seems to a decent job of preventing deadlocks due to printk, at
least in my case (I see in the comments on that thread though that
it's not perfect).

-dan
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