Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934206Ab0KQEnp (ORCPT ); Tue, 16 Nov 2010 23:43:45 -0500 Received: from mail-ww0-f44.google.com ([74.125.82.44]:43681 "EHLO mail-ww0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932950Ab0KQEnn (ORCPT ); Tue, 16 Nov 2010 23:43:43 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=subject:from:to:cc:in-reply-to:references:content-type:date :message-id:mime-version:x-mailer:content-transfer-encoding; b=aC3jJLskuv4NFF9ENcjLRf8/9UP+QVLVwXkWTm8b/UCX3+W+gmaBpPZ9S1ZTHv9i3Z iR5yPpvN6RGxZHvzOc7cCHRkJjo7dCSqm3uNPqnKnVFi8jevYAqQGdpWaymOrFo9Nc5M WI5cvDv4O7fPrWdBDDB0OX/xuiNLqavizAD0s= Subject: Re: Kernel rwlock design, Multicore and IGMP From: Eric Dumazet To: Cypher Wu Cc: Chris Metcalf , =?ISO-8859-1?Q?Am=E9rico?= Wang , linux-kernel@vger.kernel.org, netdev In-Reply-To: References: <1289489007.17691.1310.camel@edumazet-laptop> <4CDF1945.8090101@tilera.com> <1289820672.2607.10.camel@edumazet-laptop> Content-Type: text/plain; charset="UTF-8" Date: Wed, 17 Nov 2010 05:43:37 +0100 Message-ID: <1289969017.2732.82.camel@edumazet-laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.30.3 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1234 Lines: 31 Le mercredi 17 novembre 2010 à 09:30 +0800, Cypher Wu a écrit : > O > struct in_device::mr_ifc_timer. Every time when a process join/leave a > MC group, igmp_ifc_event() -> igmp_ifc_start_timer() will start the > timer on the core that the system call issued, and > igmp_ifc_timer_expire() will be called on that core in the bottem halt > of timer interrupt. > If we call join/leave on mutlicores that timers will run on all these > cores, but it seems only one or two will generate IGMP message, others > will only lock the list and loop throught it with nothing generated. > > Problem would not be timer being restarted on different cores (very small impact), but scanning a list in igmpv3_send_cr() with many items in it and expensive things, under timer handler (softirq), so adding spikes of latency. IGMP_Unsolicited_Report_Interval is 10 seconds, so we start timer in a 5 second average. I am not sure there is a need to join/leave thousand of groups per second anyway... -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/