Re: [PATCH tip/core/rcu 0/7] RCU_FAST_NO_HZ changes for 3.6

From: Ingo Molnar
Date: Fri Jun 08 2012 - 05:04:19 EST



* Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> wrote:

> Hello!
>
> This patch series provides more adjustments to the (relatively) new
> large-system-safe implementation for RCU_FAST_NO_HZ:
>
> 1. Remove RCU_FAST_NO_HZ dependency on stop_machine() nature of
> CPU hotplug.
> 2. Make RCU_FAST_NO_HZ tracing distinguish between short and
> long idle intervals.
> 3. Move RCU_FAST_NO_HZ per-CPU state variables to the rcu_dynticks
> per-CPU structure.
> 4. Precompute RCU_FAST_NO_HZ timer offsets so that the timers
> will actually be paid attention to. This fixes the slow-boot
> problem that hit a few people.
> 5. Convert ftrace_dump() calls in idle entry and idle exit from
> DUMP_ALL to DUMP_ORIG.
> 6. Fix erroneous TINY_PREEMPT_RCU assumption that rcu_preempt_needs_cpu()
> is a quiescent state (it is not).
> 7. Round RCU_FAST_NO_HZ lazy timeout to nearest second to conserve
> power on systems with synchronized scheduler-clock interrupts.
>
> I am considering pushing #1-#4 into 3.5 for the slow-boot regression.
> If you object, please let me know.

Sure, that's sensible - could get this to me ASAP so that we can
send it to Linus before -rc2? #3 and #4 are pretty large so we
want them upstream ASAP.

Thanks,

Ingo
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