From owner-freebsd-arch@FreeBSD.ORG Tue Sep 18 21:20:15 2007 Return-Path: Delivered-To: arch@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 05DC616A469; Tue, 18 Sep 2007 21:20:15 +0000 (UTC) (envelope-from jroberson@chesapeake.net) Received: from webaccess-cl.virtdom.com (webaccess-cl.virtdom.com [216.240.101.25]) by mx1.freebsd.org (Postfix) with ESMTP id BA7AC13C45D; Tue, 18 Sep 2007 21:20:14 +0000 (UTC) (envelope-from jroberson@chesapeake.net) Received: from [192.168.1.103] (c-67-160-44-208.hsd1.wa.comcast.net [67.160.44.208]) (authenticated bits=0) by webaccess-cl.virtdom.com (8.13.6/8.13.6) with ESMTP id l8ILK62s053766 (version=TLSv1/SSLv3 cipher=DHE-DSS-AES256-SHA bits=256 verify=NO); Tue, 18 Sep 2007 17:20:07 -0400 (EDT) (envelope-from jroberson@chesapeake.net) Date: Tue, 18 Sep 2007 14:22:58 -0700 (PDT) From: Jeff Roberson X-X-Sender: jroberson@10.0.0.1 To: Andre Oppermann In-Reply-To: <46EFE4BD.4030505@freebsd.org> Message-ID: <20070918142115.C558@10.0.0.1> References: <20070917165657.B558@10.0.0.1> <46EF644E.9050207@elischer.org> <20070918012555.G558@10.0.0.1> <46EFE4BD.4030505@freebsd.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Cc: arch@freebsd.org, Julian Elischer Subject: Re: Changing p_swtime and td_slptime to ticks X-BeenThere: freebsd-arch@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussion related to FreeBSD architecture List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 18 Sep 2007 21:20:15 -0000 On Tue, 18 Sep 2007, Andre Oppermann wrote: > Jeff Roberson wrote: >> On Mon, 17 Sep 2007, Julian Elischer wrote: >> >>> Jeff Roberson wrote: >>>> Enclosed is a patch that fixes swapping with ULE. ULE has never properly >>>> set p_swtime and td_slptime which are used by the swapout/swapin code to >>>> select the appropriate thread to swap. >>> >>> I have not looked at in the depth required, but 2 points that I was unable >>> to check to my satisfaction before I got called away for work.... >>> >>> 1/ the source of the ticks is a monotonically increasing count that never >>> goes backwards or changes? >> >> ticks is incremented each time hardclock() is called. That's it. >> >>> >>> 2/ nothing that used to be accounted in seconds becomes accounted for in >>> ticks? >> >> I scale back to seconds where it is required. Really I think ticks would >> be the better metric in vm_glue.c but didn't want to make any drastic >> changes. > > ticks is 2^31 on x86 and at HZ=1000 is wraps within a reasonable > short uptime. You have to make sure that your code handles that > correctly or you run into lots of strange effects which are almost > impossible to reproduce. In TCP we've got bitten by that. Thanks Andre, this is a good point. For the td_slptime I don't think it's of practical concern. However, for swtime I think I will convert it then to seconds from boot. Jeff > > -- > Andre >