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| author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2015-06-30 00:06:39 (GMT) |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2015-07-17 21:59:00 (GMT) |
| commit | 2cd6ffafec066118365f6d7eb7a42ea16c1f032c (patch) | |
| tree | 39656499f5a78c4b61528904e3464c2403a0b83b /kernel/rcu/tree.c | |
| parent | 704dd435ac7eaefa89fcd82fd2876b8330e00ff3 (diff) | |
| download | linux-2cd6ffafec066118365f6d7eb7a42ea16c1f032c.tar.xz | |
rcu: Extend expedited funnel locking to rcu_data structure
The strictly rcu_node based funnel-locking scheme works well in many
cases, but systems with CONFIG_RCU_FANOUT_LEAF=64 won't necessarily get
all that much concurrency. This commit therefore extends the funnel
locking into the per-CPU rcu_data structure, providing concurrency equal
to the number of CPUs.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel/rcu/tree.c')
| -rw-r--r-- | kernel/rcu/tree.c | 19 |
1 files changed, 16 insertions, 3 deletions
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index a905d3b..e45097fc 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -3312,11 +3312,14 @@ static bool rcu_exp_gp_seq_done(struct rcu_state *rsp, unsigned long s) /* Common code for synchronize_{rcu,sched}_expedited() work-done checking. */ static bool sync_exp_work_done(struct rcu_state *rsp, struct rcu_node *rnp, + struct rcu_data *rdp, atomic_long_t *stat, unsigned long s) { if (rcu_exp_gp_seq_done(rsp, s)) { if (rnp) mutex_unlock(&rnp->exp_funnel_mutex); + else if (rdp) + mutex_unlock(&rdp->exp_funnel_mutex); /* Ensure test happens before caller kfree(). */ smp_mb__before_atomic(); /* ^^^ */ atomic_long_inc(stat); @@ -3332,6 +3335,7 @@ static bool sync_exp_work_done(struct rcu_state *rsp, struct rcu_node *rnp, */ static struct rcu_node *exp_funnel_lock(struct rcu_state *rsp, unsigned long s) { + struct rcu_data *rdp; struct rcu_node *rnp0; struct rcu_node *rnp1 = NULL; @@ -3343,16 +3347,24 @@ static struct rcu_node *exp_funnel_lock(struct rcu_state *rsp, unsigned long s) * can be inexact, as it is just promoting locality and is not * strictly needed for correctness. */ - rnp0 = per_cpu_ptr(rsp->rda, raw_smp_processor_id())->mynode; + rdp = per_cpu_ptr(rsp->rda, raw_smp_processor_id()); + if (sync_exp_work_done(rsp, NULL, NULL, &rsp->expedited_workdone1, s)) + return NULL; + mutex_lock(&rdp->exp_funnel_mutex); + rnp0 = rdp->mynode; for (; rnp0 != NULL; rnp0 = rnp0->parent) { - if (sync_exp_work_done(rsp, rnp1, &rsp->expedited_workdone1, s)) + if (sync_exp_work_done(rsp, rnp1, rdp, + &rsp->expedited_workdone2, s)) return NULL; mutex_lock(&rnp0->exp_funnel_mutex); if (rnp1) mutex_unlock(&rnp1->exp_funnel_mutex); + else + mutex_unlock(&rdp->exp_funnel_mutex); rnp1 = rnp0; } - if (sync_exp_work_done(rsp, rnp1, &rsp->expedited_workdone2, s)) + if (sync_exp_work_done(rsp, rnp1, rdp, + &rsp->expedited_workdone3, s)) return NULL; return rnp1; } @@ -3733,6 +3745,7 @@ rcu_boot_init_percpu_data(int cpu, struct rcu_state *rsp) WARN_ON_ONCE(atomic_read(&rdp->dynticks->dynticks) != 1); rdp->cpu = cpu; rdp->rsp = rsp; + mutex_init(&rdp->exp_funnel_mutex); rcu_boot_init_nocb_percpu_data(rdp); raw_spin_unlock_irqrestore(&rnp->lock, flags); } |