d21670acab
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> |
||
|---|---|---|
| .. | ||
| 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 | ||