From mboxrd@z Thu Jan 1 00:00:00 1970 From: Guus Sliepen Subject: Re: Best way to reduce system call overhead for tun device I/O? Date: Fri, 1 Apr 2016 00:28:57 +0200 Message-ID: <20160331222857.GH3771@sliepen.org> References: <20160329224043.GY3784@sliepen.org> <20160331.172050.1423948167839485574.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: tom@herbertland.com, netdev@vger.kernel.org To: David Miller Return-path: Received: from arianus.sliepen.org ([92.243.30.131]:37685 "EHLO arianus.sliepen.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757369AbcCaW3A (ORCPT ); Thu, 31 Mar 2016 18:29:00 -0400 Content-Disposition: inline In-Reply-To: <20160331.172050.1423948167839485574.davem@davemloft.net> Sender: netdev-owner@vger.kernel.org List-ID: On Thu, Mar 31, 2016 at 05:20:50PM -0400, David Miller wrote: > >> I'm trying to reduce system call overhead when reading/writing to/from a > >> tun device in userspace. [...] What would be the right way to do this? > >> > > Personally I think tun could benefit greatly if it were implemented as > > a socket instead of character interface. One thing that could be much > > better is sending/receiving of meta data attached to skbuf. For > > instance GSO data could be in ancillary data in a socket instead of > > inline with packet data as tun seems to be doing now. > > Agreed. Ok. So how should the userspace API work? Creating an AF_PACKET socket and then using a tun ioctl to create a tun interface and bind it to the socket? int fd = socket(AF_PACKET, ...) struct ifreq ifr = {...}; ioctl(fd, TUNSETIFF, &ifr); -- Met vriendelijke groet / with kind regards, Guus Sliepen