On 06/16/2015 05:41 PM, Steven Rostedt wrote:
On Tue, 16 Jun 2015 14:38:53 +0200
Daniel Wagner <w...@monom.org> wrote:
*map, void *key)
        if (l) {
                hlist_del_rcu(&l->hash_node);
                htab->count--;
-               kfree_rcu(l, rcu);
+               /* kfree_rcu(l, rcu); */

So this kfree_rcu() is only being used to defer a free, and has nothing
to do with having to free 'l' from rcu?

Not 100% sure but I got the impression kfree_rcu only defers the free.

+static int free_thread(void *arg)
+{
+       unsigned long flags;
+       struct htab_elem *l;
+
+       while (!kthread_should_stop()) {
+               spin_lock_irqsave(&elem_freelist_lock, flags);
+               while (!list_empty(&elem_freelist)) {
+                       l = list_entry(elem_freelist.next,
+                               struct htab_elem, list);
+                       list_del(&l->list);
+                       kfree(l);
+               }
+               spin_unlock_irqrestore(&elem_freelist_lock, flags);

Wow! This is burning up CPU isn't it?

Sure, this is a very busy thread :) I was just experimenting if defering it to a thread would paper of the problem.

If you just need to delay the kfree, why not use irq_work for that job?

Good point. I tried that tomorrow.

cheers,
daniel
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