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rcu: simplify the usage of percpu data

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&percpu_data is compatible with allocated percpu data.

And we use it and remove the "->rda[NR_CPUS]" array, saving significant
storage on systems with large numbers of CPUs.  This does add an additional
level of indirection and thus an additional cache line referenced, but
because ->rda is not used on the read side, this is OK.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Reviewed-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
This commit is contained in:
Lai Jiangshan 2010-06-28 16:25:04 +08:00 • committed by Paul E. McKenney
parent e546f485e1
commit 394f99a900
4 changed files with 19 additions and 31 deletions
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2
kernel/rcutree.h
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@ -283,7 +283,7 @@ struct rcu_state {
struct rcu_node *level[NUM_RCU_LVLS]; /* Hierarchy levels. */
u32 levelcnt[MAX_RCU_LVLS + 1]; /* # nodes in each level. */
u8 levelspread[NUM_RCU_LVLS]; /* kids/node in each level. */
struct rcu_data *rda[NR_CPUS]; /* array of rdp pointers. */
struct rcu_data __percpu *rda; /* pointer of percu rcu_data. */
/* The following fields are guarded by the root rcu_node's lock. */