From owner-freebsd-arch@FreeBSD.ORG Thu Nov 11 06:00:13 2004 Return-Path: Delivered-To: freebsd-arch@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id B6EFB16A4D0; Thu, 11 Nov 2004 06:00:13 +0000 (GMT) Received: from pimout3-ext.prodigy.net (pimout3-ext.prodigy.net [207.115.63.102]) by mx1.FreeBSD.org (Postfix) with ESMTP id DD64143D4C; Thu, 11 Nov 2004 06:00:08 +0000 (GMT) (envelope-from julian@elischer.org) Received: from [192.168.1.102] (adsl-68-123-122-146.dsl.snfc21.pacbell.net [68.123.122.146])iAB606Q7046920; Thu, 11 Nov 2004 01:00:07 -0500 Message-ID: <4192FFE5.8060205@elischer.org> Date: Wed, 10 Nov 2004 22:00:05 -0800 From: Julian Elischer User-Agent: Mozilla/5.0 (X11; U; FreeBSD i386; en-US; rv:1.8a3) Gecko/20041017 X-Accept-Language: en, hu MIME-Version: 1.0 To: Scott Long References: <20041111030035.GA70923@VARK.MIT.EDU> <4192D9AB.5060309@freebsd.org> In-Reply-To: <4192D9AB.5060309@freebsd.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit cc: arch@freebsd.org cc: David Schultz Subject: Re: U Area Removal X-BeenThere: freebsd-arch@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Discussion related to FreeBSD architecture List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 11 Nov 2004 06:00:13 -0000 Scott Long wrote: > David Schultz wrote: > >> Over the years, the amount of data we have stored in each process' U >> area has eroded to the point where all we have left are the following: >> >> - A struct kinfo_proc that is only used for a.out core dumps. >> This can be reconstructed at the time of the core dump, so >> it doesn't need to be there. >> >> - The struct pstats for the process, which takes a mere 216 bytes >> on i386. >> >> In exchange for the ability to swap out this 216-byte structure, we >> keep around a 4096-byte page, a 132-byte vm_object, and a couple of >> pointers. Moreover, there is a small amount of runtime overhead >> associated with this, and developers need to remember to PHOLD() and >> PRELE() the process as appropriate.[1] >> >> I propose to remove the ability to swap the U area, allocating p_stats >> from malloced memory instead. Medium-term scheduling and swapping of >> kernel stacks would be retained. Here are the patches; !i386 testers >> wanted: >> >> http://www.freebsd.org/~das/patches/upages.diff >> >> >> [1] Most of the instances of PHOLD() and PRELE() right now never >> needed to be there or have been unnecessary ever since the PCB >> was moved out of the U area. > We've been slowly working towards this.. when we moved the pcb out to the thread this became inevitable.. go for it! > > Go for it! Just get some validation that amd64 and sparc64 work, and > then do the deed. I'll try testing at least amd64 right now. > > Scott > _______________________________________________ > freebsd-arch@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-arch > To unsubscribe, send any mail to "freebsd-arch-unsubscribe@freebsd.org"