From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755666Ab2CBRGf (ORCPT ); Fri, 2 Mar 2012 12:06:35 -0500 Received: from lxorguk.ukuu.org.uk ([81.2.110.251]:33527 "EHLO lxorguk.ukuu.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752833Ab2CBRGd (ORCPT ); Fri, 2 Mar 2012 12:06:33 -0500 Date: Fri, 2 Mar 2012 17:08:23 +0000 From: Alan Cox To: Javier Martinez Canillas Cc: Eric Dumazet , David Miller , shemminger@vyatta.com, ying.xue@windriver.com, luiz.dentz@gmail.com, rodrigo.moya@collabora.co.uk, javier@collabora.co.uk, lennart@poettering.net, kay.sievers@vrfy.org, alban.crequy@collabora.co.uk, bart.cerneels@collabora.co.uk, sjoerd.simons@collabora.co.uk, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Marcel Holtmann Subject: Re: [PATCH 0/10] af_unix: add multicast and filtering features to AF_UNIX Message-ID: <20120302170823.7117821b@pyramind.ukuu.org.uk> In-Reply-To: <4F50F6AA.9050909@collabora.co.uk> References: <20120301.170848.432407217191581288.davem@davemloft.net> <20120302.035509.1994457175982020283.davem@davemloft.net> <4F509274.9060302@collabora.co.uk> <1330694031.2469.15.camel@edumazet-laptop> <4F50F6AA.9050909@collabora.co.uk> X-Mailer: Claws Mail 3.8.0 (GTK+ 2.24.8; x86_64-redhat-linux-gnu) Face: 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 Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > 2- The transport layer used by D-bus is not performance sensitive > basically due: > > a) high number of context switches required to send messages between peer. This is a user space design issue. The fact dbus wakes up so much stuff wants fixing at the dbus level. > b) the D-bus daemon doing the routing and being a bottleneck of the whole. This is a userspace design issue. > c) amount of messages copied between kernel space and user space. This is mostly a userspace design issue and fixing a would fix much of c because you wouldn't keep sending people crap they didn't need. You've already got multicast facilities in kernel (if dbus must work by shouting not state change subscription like saner setups), and you've got BPF filtering facilities to try and cure some of the wakeups even doing multicast. Beyond that I don't see what the kernel can do given its mostly an architectural problem. Your model appears to be "since its causing enormous amounts of work we should do the work faster". The right model would appear to me to be "We shouldn't cause enormous amounts of work" Alan