From: Eric Dumazet <eric.dumazet@gmail.com>
To: Jason Wang <jasowang@redhat.com>
Cc: krkumar2@in.ibm.com, kvm@vger.kernel.org, mst@redhat.com,
qemu-devel@nongnu.org, netdev@vger.kernel.org,
rusty@rustcorp.com.au, linux-kernel@vger.kernel.org,
virtualization@lists.linux-foundation.org,
mirq-linux@rere.qmqm.pl, davem@davemloft.net
Subject: Re: [net-next RFC PATCH 4/7] tuntap: multiqueue support
Date: Fri, 12 Aug 2011 16:29:36 +0200 [thread overview]
Message-ID: <1313159376.2354.26.camel@edumazet-HP-Compaq-6005-Pro-SFF-PC> (raw)
In-Reply-To: <20110812015520.31613.99890.stgit@intel-e5620-16-2.englab.nay.redhat.com>
Le vendredi 12 août 2011 à 09:55 +0800, Jason Wang a écrit :
>+ rxq = skb_get_rxhash(skb);
>+ if (rxq) {
>+ tfile = rcu_dereference(tun->tfiles[rxq % numqueues]);
>+ if (tfile)
>+ goto out;
>+ }
You can avoid an expensive divide with following trick :
u32 idx = ((u64)rxq * numqueues) >> 32;
> -static struct tun_struct *tun_get(struct file *file)
> +static void tun_detach_all(struct net_device *dev)
> {
> - return __tun_get(file->private_data);
> + struct tun_struct *tun = netdev_priv(dev);
> + struct tun_file *tfile, *tfile_list[MAX_TAP_QUEUES];
> + int i, j = 0;
> +
> + spin_lock(&tun_lock);
> +
> + for (i = 0; i < MAX_TAP_QUEUES && tun->numqueues; i++) {
> + tfile = rcu_dereference_protected(tun->tfiles[i],
> + lockdep_is_held(&tun_lock));
> + if (tfile) {
> + wake_up_all(&tfile->wq.wait);
> + tfile_list[i++] = tfile;
typo here, you want tfile_list[j++] = tfile;
> + rcu_assign_pointer(tun->tfiles[i], NULL);
> + rcu_assign_pointer(tfile->tun, NULL);
> + --tun->numqueues;
> + }
> + }
> + BUG_ON(tun->numqueues != 0);
> + spin_unlock(&tun_lock);
> +
> + synchronize_rcu();
> + for(--j; j >= 0; j--)
> + sock_put(&tfile_list[j]->sk);
> }
>
Could you take a look at net/packet/af_packet.c, to check how David did
the whole fanout thing ?
__fanout_unlink()
Trick is to not leave NULL entries in the tun->tfiles[] array.
It makes things easier in hot path.
next prev parent reply other threads:[~2011-08-12 14:29 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-08-12 1:54 [net-next RFC PATCH 0/7] multiqueue support for tun/tap Jason Wang
2011-08-12 1:54 ` [net-next RFC PATCH 1/7] tuntap: move socket/sock related structures to tun_file Jason Wang
2011-08-12 1:55 ` [net-next RFC PATCH 2/7] tuntap: categorize ioctl Jason Wang
2011-08-12 1:55 ` [net-next RFC PATCH 3/7] tuntap: introduce multiqueue related flags Jason Wang
2011-08-12 1:55 ` [net-next RFC PATCH 4/7] tuntap: multiqueue support Jason Wang
2011-08-12 14:29 ` Eric Dumazet [this message]
2011-08-14 6:05 ` Jason Wang
2011-08-12 23:21 ` Paul E. McKenney
2011-08-14 6:07 ` Jason Wang
2011-08-12 1:55 ` [net-next RFC PATCH 5/7] tuntap: add ioctls to attach or detach a file form tap device Jason Wang
2011-08-12 1:55 ` [net-next RFC PATCH 6/7] Change virtqueue structure Jason Wang
2011-08-12 1:55 ` [net-next RFC PATCH 7/7] virtio-net changes Jason Wang
2011-08-12 9:09 ` Sasha Levin
2011-08-14 5:59 ` Jason Wang
2011-08-17 13:24 ` WANG Cong
2011-08-12 2:11 ` [net-next RFC PATCH 0/7] multiqueue support for tun/tap Jason Wang
2011-08-13 0:46 ` Sridhar Samudrala
2011-08-14 6:19 ` Jason Wang
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1313159376.2354.26.camel@edumazet-HP-Compaq-6005-Pro-SFF-PC \
--to=eric.dumazet@gmail.com \
--cc=davem@davemloft.net \
--cc=jasowang@redhat.com \
--cc=krkumar2@in.ibm.com \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mirq-linux@rere.qmqm.pl \
--cc=mst@redhat.com \
--cc=netdev@vger.kernel.org \
--cc=qemu-devel@nongnu.org \
--cc=rusty@rustcorp.com.au \
--cc=virtualization@lists.linux-foundation.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).