diff options
| author | Joel Fernandes (Google) | 2020-03-16 12:32:28 -0400 |
|---|---|---|
| committer | Paul E. McKenney | 2020-04-27 11:02:50 -0700 |
| commit | a6a82ce18ba443186545d3fefbee8b9419a859dc (patch) | |
| tree | ab1829c8e55a433ebd52e812da3f34462a9bc39f /kernel/rcu/tree.c | |
| parent | 9154244c1ab6c9db4f1f25ac8f73bd46dba64287 (diff) | |
rcu/tree: Count number of batched kfree_rcu() locklessly
We can relax the correctness of counting of number of queued objects in
favor of not hurting performance, by locklessly sampling per-cpu
counters. This should be Ok since under high memory pressure, it should not
matter if we are off by a few objects while counting. The shrinker will
still do the reclaim.
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
[ paulmck: Remove unused "flags" variable. ]
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Diffstat (limited to 'kernel/rcu/tree.c')
| -rw-r--r-- | kernel/rcu/tree.c | 10 |
1 files changed, 4 insertions, 6 deletions
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index e299cd0ddd97..3f1f57411fe1 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -2939,7 +2939,7 @@ static inline bool queue_kfree_rcu_work(struct kfree_rcu_cpu *krcp) krcp->head = NULL; } - krcp->count = 0; + WRITE_ONCE(krcp->count, 0); /* * One work is per one batch, so there are two "free channels", @@ -3077,7 +3077,7 @@ void kfree_call_rcu(struct rcu_head *head, rcu_callback_t func) krcp->head = head; } - krcp->count++; + WRITE_ONCE(krcp->count, krcp->count + 1); // Set timer to drain after KFREE_DRAIN_JIFFIES. if (rcu_scheduler_active == RCU_SCHEDULER_RUNNING && @@ -3097,15 +3097,13 @@ static unsigned long kfree_rcu_shrink_count(struct shrinker *shrink, struct shrink_control *sc) { int cpu; - unsigned long flags, count = 0; + unsigned long count = 0; /* Snapshot count of all CPUs */ for_each_online_cpu(cpu) { struct kfree_rcu_cpu *krcp = per_cpu_ptr(&krc, cpu); - spin_lock_irqsave(&krcp->lock, flags); - count += krcp->count; - spin_unlock_irqrestore(&krcp->lock, flags); + count += READ_ONCE(krcp->count); } return count; |