From: Eric Dumazet <eric.duma...@gmail.com> Date: Fri, 17 Oct 2014 09:28:03 -0700
> On Fri, 2014-10-17 at 07:25 +0100, Thomas Graf wrote: >> On 10/17/14 at 02:34am, Steinar H. Gunderson wrote: >> > On Fri, Oct 17, 2014 at 02:21:32AM +0200, Steinar H. Gunderson wrote: >> > > Hi, >> > > >> > > We recently upgraded a machine from 3.14.5 to 3.17.1, and a Perl script >> > > we're >> > > running to poll SNMP suddenly needed ten times as much time to complete. >> > >> > e341694e3eb57fcda9f1adc7bfea42fe080d8d7a looks like it might cause >> > something >> > like this (it certainly added the synchronize_net() call). Cc-ing people >> > on >> > that commit; quoting the entire rest of the message for reference. >> >> I think the only option at this point is to re-add the nltable lock to >> netlink_lookup() so we can drop the synchronize_net() until we find a >> way to RCUify socket destruction. I will cook up a patch today unless >> somebody can come up with a smarter way to work around needing the >> synchronize_net(). > > I had a patch to add conditional RCUify socket destruction for some kind > of sockets (opt-in at protocol level). > > I needed this to remove too expensive UDP socket refcount inc/dec (so > get rid of SLAB_DESTROY_BY_RCU, and instead use call_rcu() or kfree_rcu > thing) > > But I couldn't finish and submit this for 3.18, and I believe I got it > wrong anyway. Cant remember exact details right now, maybe later in the > day, once my headache is better. Can I ask a serious question? What is the synchronize_net() in AF_NETLINK exactly needed for? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
