![]() Lai Jiangshan noted that up to 10% of the RCU_SOFTIRQ are spurious, and traced this down to the fact that the current grace-period machinery will uselessly raise RCU_SOFTIRQ when a given CPU needs to go through a quiescent state, but has not yet done so. In this situation, there might well be nothing that RCU_SOFTIRQ can do, and the overhead can be worth worrying about in the ksoftirqd case. This patch therefore avoids raising RCU_SOFTIRQ in this situation. Changes since v1 (http://lkml.org/lkml/2010/3/30/122 from Lai Jiangshan): o Omit the rcu_qs_pending() prechecks, as they aren't that much less expensive than the quiescent-state checks. o Merge with the set_need_resched() patch that reduces IPIs. o Add the new n_rp_report_qs field to the rcu_pending tracing output. o Update the tracing documentation accordingly. Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> |
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00-INDEX | ||
arrayRCU.txt | ||
checklist.txt | ||
listRCU.txt | ||
lockdep.txt | ||
NMI-RCU.txt | ||
rcu.txt | ||
rcubarrier.txt | ||
rculist_nulls.txt | ||
rcuref.txt | ||
RTFP.txt | ||
stallwarn.txt | ||
torture.txt | ||
trace.txt | ||
UP.txt | ||
whatisRCU.txt |