From owner-freebsd-current@FreeBSD.ORG Mon Oct 19 15:05:42 2009 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 0E6E51065679 for ; Mon, 19 Oct 2009 15:05:42 +0000 (UTC) (envelope-from rwatson@FreeBSD.org) Received: from cyrus.watson.org (cyrus.watson.org [65.122.17.42]) by mx1.freebsd.org (Postfix) with ESMTP id DC7AF8FC1B for ; Mon, 19 Oct 2009 15:05:41 +0000 (UTC) Received: from fledge.watson.org (fledge.watson.org [65.122.17.41]) by cyrus.watson.org (Postfix) with ESMTPS id 7698546B06; Mon, 19 Oct 2009 11:05:41 -0400 (EDT) Date: Mon, 19 Oct 2009 16:05:41 +0100 (BST) From: Robert Watson X-X-Sender: robert@fledge.watson.org To: Taku YAMAMOTO In-Reply-To: <20091018202407.656c3863.taku@tackymt.homeip.net> Message-ID: References: <20091018202407.656c3863.taku@tackymt.homeip.net> User-Agent: Alpine 2.00 (BSF 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Cc: freebsd-current@freebsd.org Subject: Re: softclock swis not bound to specific cpu X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 19 Oct 2009 15:05:42 -0000 On Sun, 18 Oct 2009, Taku YAMAMOTO wrote: > I noticed that the softclock threads didn't seem to be bound to any cpu. > > I'm not sure whether it's the Right Thing (TM) to bind them to the > corresponding cpus though: it might be good to give the scheduler a chance > to rebalance callouts. > > I'm about to test the modification like the attached diff. Comments are > welcome. Yes, I think the intent is that they have a "soft" affinity to the CPU where the lapic timer is firing, but not a hard binding, allowing them to migrate if required. It would be interesting to measure how effective that soft affinity is in practice under various loads -- presumably the goal would be for the softclock thread to migrate if a higher (lower) priority thread is hogging the CPU. Robert N M Watson Computer Laboratory University of Cambridge