From: Paul E. McKenney <paul.mckenney@linaro.org>
Date: Fri, 17 Feb 2012 05:59:33 +0000 (-0800)
Subject: rcu: Hold off RCU_FAST_NO_HZ after timer posted
X-Git-Tag: v3.4-rc1~194^2^2~1
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=696a02cc16b182dd78b1f395ae336f449cc90f11;p=pandora-kernel.git

rcu: Hold off RCU_FAST_NO_HZ after timer posted

This commit handles workloads that transition quickly between idle and
non-idle, and where the CPU's callbacks cannot be invoked, but where
RCU does not have anything immediate for the CPU to do.  Without this
patch, the RCU_FAST_NO_HZ code can be invoked repeatedly on each entry
to idle.  The commit sets the per-CPU rcu_dyntick_holdoff variable to
hold off further attempts for a tick.

Reported-by: "Abou Gazala, Neven M" <neven.m.abou.gazala@intel.com>
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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