From owner-freebsd-hackers@FreeBSD.ORG Thu Jun 1 07:30:22 2006 Return-Path: X-Original-To: freebsd-hackers@freebsd.org Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 0402C16BEFC; Thu, 1 Jun 2006 07:30:22 +0000 (UTC) (envelope-from Alexander@Leidinger.net) Received: from www.ebusiness-leidinger.de (jojo.ms-net.de [84.16.236.246]) by mx1.FreeBSD.org (Postfix) with ESMTP id 851CD43D7B; Thu, 1 Jun 2006 07:30:19 +0000 (GMT) (envelope-from Alexander@Leidinger.net) Received: from Andro-Beta.Leidinger.net (p54A5D7E5.dip.t-dialin.net [84.165.215.229]) (authenticated bits=0) by www.ebusiness-leidinger.de (8.13.4/8.13.4) with ESMTP id k517TBih097703; Thu, 1 Jun 2006 09:29:12 +0200 (CEST) (envelope-from Alexander@Leidinger.net) Received: from localhost (localhost [127.0.0.1]) by Andro-Beta.Leidinger.net (8.13.4/8.13.3) with ESMTP id k517UGMa085619; Thu, 1 Jun 2006 09:30:16 +0200 (CEST) (envelope-from Alexander@Leidinger.net) Received: from pslux.cec.eu.int (pslux.cec.eu.int [158.169.9.14]) by webmail.leidinger.net (Horde MIME library) with HTTP; Thu, 01 Jun 2006 09:30:16 +0200 Message-ID: <20060601093016.ygeptkv80840gkww@netchild.homeip.net> X-Priority: 3 (Normal) Date: Thu, 01 Jun 2006 09:30:16 +0200 From: Alexander Leidinger To: Attilio Rao References: <3bbf2fe10605311156p7e629283r34d22b368877582d@mail.gmail.com> <447DFA0C.20207@FreeBSD.org> <3bbf2fe10605311329h7adc1722j9088253515e0265b@mail.gmail.com> <20060601084052.D32549@delplex.bde.org> <3bbf2fe10605311632w58c2949buc072e58ac103d7d@mail.gmail.com> In-Reply-To: <3bbf2fe10605311632w58c2949buc072e58ac103d7d@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; DelSp="Yes"; format="flowed" Content-Disposition: inline Content-Transfer-Encoding: quoted-printable User-Agent: Internet Messaging Program (IMP) H3 (4.1) / FreeBSD-4.11 X-Virus-Scanned: by amavisd-new X-Mailman-Approved-At: Thu, 01 Jun 2006 12:03:11 +0000 Cc: freebsd-hackers@freebsd.org, Suleiman Souhlal , Bruce Evans , freebsd-arch@freebsd.org Subject: Re: [patch] Adding optimized kernel copying support - Part III X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 01 Jun 2006 07:30:59 -0000 Quoting Attilio Rao (from Thu, 1 Jun 2006 =20 01:32:12 +0200): > 2006/6/1, Bruce Evans : >> The new code wouldn't behave much differently under SMP. It just might >> be a smaller optimization because more memory pressure for SMP causes >> more cache misses for everything and there are no benefits from copying >> through MMX/XMM unless nontemporal writes are used. All (?) CPUs with >> MMX or SSE* can saturate main memory using 32-bit instructions. On >> 32-bit CPUs, the benefits of using MMX/XMM come from being able to >> saturate the L1 cache on some CPUs (mainly Athlons and not P[2-4]), >> and from being able to use nontemporal writes on some CPUs (at least >> AthlonXP via SSE extensions all CPUs with SSE2). > > I was just speaking about the copying routine itself and not about the > SSE2 environment preserving mechanism. It remains untouched in SMP > case. AFAIR the DFly FPU rework allows to use FPU/XMM instructions in their =20 kernel without the need to do some manual state preserving (it's done =20 automatically on demand). So one could use XMM instructions in RAID 5 =20 or crypto parts of the code to test if it is a performance benefit. Do =20 I understand the above part right that with this patch this is also =20 the case for us in the UP case, but not in the SMP case? Bye, Alexander. --=20 Selling GoodYear Eagle F1 235/40ZR18, 2x 4mm + 2x 5mm, ~150 EUR you have to pick it up between Germany/Saarland and Luxembourg/Capellen http://www.Leidinger.net Alexander @ Leidinger.net: PGP ID =3D B0063FE7 http://www.FreeBSD.org netchild @ FreeBSD.org : PGP ID =3D 72077137