On Sat, 09 Apr 2016 05:34:38 -0700 Eric Dumazet <eric.dumazet@xxxxxxxxx> wrote:
> On Sat, 2016-04-09 at 11:11 +0200, Jesper Dangaard Brouer wrote:
>
> > Above code is okay. But do you think we also can get away with the same
> > trick we do with the SKB refcnf? Where we avoid an atomic operation if
> > refcnt==1.
> >
> > void kfree_skb(struct sk_buff *skb)
> > {
> > if (unlikely(!skb))
> > return;
> > if (likely(atomic_read(&skb->users) == 1))
> > smp_rmb();
> > else if (likely(!atomic_dec_and_test(&skb->users)))
> > return;
> > trace_kfree_skb(skb, __builtin_return_address(0));
> > __kfree_skb(skb);
> > }
> > EXPORT_SYMBOL(kfree_skb);
>
> No we can not use this trick this for pages :
>
> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=ec91698360b3818ff426488a1529811f7a7ab87f
>
If we have a page-pool recycle facility, then we could use the trick,
right? (As we know that get_page_unless_zero() cannot happen for pages
in the pool).
--
Best regards,
Jesper Dangaard Brouer
MSc.CS, Principal Kernel Engineer at Red Hat
Author of http://www.iptv-analyzer.org
LinkedIn: http://www.linkedin.com/in/brouer
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