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| author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2018-04-24 20:03:39 +0200 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2018-06-25 20:25:41 +0200 |
| commit | 5257514d8885b2ebc11bf359ea1527282b47a5fd (patch) | |
| tree | 7c39cb001d70f457cf4873ce2b00cec9001e0bdf /kernel | |
| parent | Linux 4.18-rc1 (diff) | |
| download | linux-5257514d8885b2ebc11bf359ea1527282b47a5fd.tar.xz linux-5257514d8885b2ebc11bf359ea1527282b47a5fd.zip | |
rcu: Make expedited grace period use direct call on last leaf
During expedited grace-period initialization, a work item is scheduled
for each leaf rcu_node structure. However, that initialization code
is itself (normally) executing from a workqueue, so one of the leaf
rcu_node structures could just as well be handled by that pre-existing
workqueue, and with less overhead. This commit therefore uses a
shiny new rcu_is_leaf_node() macro to execute the last leaf rcu_node
structure's initialization directly from the pre-existing workqueue.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/rcu/rcu.h | 3 | ||||
| -rw-r--r-- | kernel/rcu/tree_exp.h | 5 |
2 files changed, 6 insertions, 2 deletions
diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h index 40cea6735c2d..db0870acfdff 100644 --- a/kernel/rcu/rcu.h +++ b/kernel/rcu/rcu.h @@ -276,6 +276,9 @@ static inline void rcu_init_levelspread(int *levelspread, const int *levelcnt) /* Is this rcu_node a leaf? */ #define rcu_is_leaf_node(rnp) ((rnp)->level == rcu_num_lvls - 1) +/* Is this rcu_node the last leaf? */ +#define rcu_is_last_leaf_node(rsp, rnp) ((rnp) == &(rsp)->node[rcu_num_nodes - 1]) + /* * Do a full breadth-first scan of the rcu_node structures for the * specified rcu_state structure. diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h index d40708e8c5d6..c6385ee1af65 100644 --- a/kernel/rcu/tree_exp.h +++ b/kernel/rcu/tree_exp.h @@ -486,8 +486,9 @@ static void sync_rcu_exp_select_cpus(struct rcu_state *rsp, rnp->rew.rew_func = func; rnp->rew.rew_rsp = rsp; if (!READ_ONCE(rcu_par_gp_wq) || - rcu_scheduler_active != RCU_SCHEDULER_RUNNING) { - /* No workqueues yet. */ + rcu_scheduler_active != RCU_SCHEDULER_RUNNING || + rcu_is_last_leaf_node(rsp, rnp)) { + /* No workqueues yet or last leaf, do direct call. */ sync_rcu_exp_select_node_cpus(&rnp->rew.rew_work); continue; } |