Re: [PATCH rcu/urgent] Banishing kthreads

From: Mathieu Desnoyers
Date: Fri Jun 17 2011 - 16:35:46 EST


* Paul E. McKenney (paulmck@xxxxxxxxxxxxxxxxxx) wrote:
> This patchset banishes RCU kthreads from non-RCU_BOOST kernel threads.
> The two patches are as follows:
>
> 1. Minimal patch that #ifdefs out the kthread code.
>
> 2. Code-movement patch that puts the code #ifdefed out above
> under existing #ifdefs in kernel/rcutree_plugin.h.

Hi Paul,

I'm wondering about the impact of this change: so I guess that before
the change, it was OK to go on a waitqueue (might_sleep()) within a
call_rcu callback, but since the execution now moves to a softirq
handler in non-RCU_BOOST kernels, it's not allowed anymore. I might be
missing something though: was sleeping within call_rcu handlers already
prohibited ? (never had to sleep in those, so I never had to check if it
was allowed)

Thanks,

Mathieu

--
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com
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