From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: tuntap: Overload handling Date: Thu, 14 Feb 2013 09:01:30 -0800 Message-ID: <1360861290.6884.55.camel@edumazet-glaptop> References: <1360859547.6884.51.camel@edumazet-glaptop> <20130214164053.GB18721@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: Sebastian =?ISO-8859-1?Q?P=F6hn?= , netdev@vger.kernel.org To: "Michael S. Tsirkin" Return-path: Received: from mail-pa0-f48.google.com ([209.85.220.48]:49729 "EHLO mail-pa0-f48.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934609Ab3BNRBe (ORCPT ); Thu, 14 Feb 2013 12:01:34 -0500 Received: by mail-pa0-f48.google.com with SMTP id hz10so1388408pad.21 for ; Thu, 14 Feb 2013 09:01:33 -0800 (PST) In-Reply-To: <20130214164053.GB18721@redhat.com> Sender: netdev-owner@vger.kernel.org List-ID: On Thu, 2013-02-14 at 18:42 +0200, Michael S. Tsirkin wrote: > Hmm so ~1000 packets in the tun queue is not enough? > You always have the option to increase it some more ... > > > You should ask Michael S. Tsirkin, as he removed the flow control > > in commit 5d097109257c03a71845729f8db6b5770c4bbedc > > (tun: only queue packets on device) > > > > Eric in the past you said the following things > (http://lkml.indiana.edu/hypermail/linux/kernel/1204.1/00784.html) > > > In your case I would just not use qdisc at all, like other virtual > > > devices. > ... > > > Anyway, with a 500 packet limit in TUN queue itself, qdisc layer should > > > be always empty. Whats the point storing more than 500 packets for a > > > device ? Thats a latency killer. > you don't think this applies, anymore? > Users have the choice to setup a qdisc or not. Having no qdisc can help raw performance, at the expense of bufferbloat. Thats all I was saying. It seems tun.c has no longer the possibility to effectively use a qdisc, (allowing the queue to buildup at qdisc layer)