On Thu, Apr 7, 2011 at 8:13 PM, Eric Dumazet wrote: > Le jeudi 07 avril 2011 à 13:57 +0200, Eric Dumazet a écrit : > >> We had a similar memory problem in fib_trie in the past  : We force a >> synchronize_rcu() every XXX Mbytes allocated to make sure we dont have >> too much ram waiting to be freed in rcu queues. I don't think there is too much memory allocated by vmalloc to free. My patch should reduce the size of the memory allocated by vmalloc(). I think the real problem is kfree always returns the memory, whose size is aligned to 2^n pages, and more memory are used than before. > > This was done in commit c3059477fce2d956 > (ipv4: Use synchronize_rcu() during trie_rebalance()) > > It was possible in fib_trie because we hold RTNL lock, so managing > a counter was free. > > In fs case, we might use a percpu_counter if we really want to limit the > amount of space. > > Now, I am not even sure we should care that much and could just forget > about this high order pages use. In normal cases, only a few fds are used, the ftable isn't larger than one page, so we should use kmalloc to reduce the memory cost. Maybe we should set a upper limit for kmalloc() here. One page? azurlt, would you please test the patch attached? Thanks. -- Regards, Changli Gao(xiaosuo@gmail.com)