From owner-freebsd-arch@FreeBSD.ORG Tue Dec 25 20:49:02 2012 Return-Path: Delivered-To: arch@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 50A5EFBC; Tue, 25 Dec 2012 20:49:02 +0000 (UTC) (envelope-from kostikbel@gmail.com) Received: from kib.kiev.ua (kib.kiev.ua [IPv6:2001:470:d5e7:1::1]) by mx1.freebsd.org (Postfix) with ESMTP id DF1D28FC16; Tue, 25 Dec 2012 20:49:01 +0000 (UTC) Received: from tom.home (kostik@localhost [127.0.0.1]) by kib.kiev.ua (8.14.5/8.14.5) with ESMTP id qBPKmsUJ058519; Tue, 25 Dec 2012 22:48:54 +0200 (EET) (envelope-from kostikbel@gmail.com) DKIM-Filter: OpenDKIM Filter v2.7.3 kib.kiev.ua qBPKmsUJ058519 Received: (from kostik@localhost) by tom.home (8.14.5/8.14.5/Submit) id qBPKms2B058518; Tue, 25 Dec 2012 22:48:54 +0200 (EET) (envelope-from kostikbel@gmail.com) X-Authentication-Warning: tom.home: kostik set sender to kostikbel@gmail.com using -f Date: Tue, 25 Dec 2012 22:48:54 +0200 From: Konstantin Belousov To: Robert Watson Subject: Re: Unmapped I/O Message-ID: <20121225204854.GE82219@kib.kiev.ua> References: <20121219135451.GU71906@kib.kiev.ua> <50D22EA6.1040501@rice.edu> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="ey/N+yb7u/X9mFhi" Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) X-Spam-Status: No, score=-2.0 required=5.0 tests=ALL_TRUSTED,BAYES_00, DKIM_ADSP_CUSTOM_MED,FREEMAIL_FROM,NML_ADSP_CUSTOM_MED autolearn=no version=3.3.2 X-Spam-Checker-Version: SpamAssassin 3.3.2 (2011-06-06) on tom.home Cc: alc@freebsd.org, arch@freebsd.org, Alan Cox X-BeenThere: freebsd-arch@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Discussion related to FreeBSD architecture List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 25 Dec 2012 20:49:02 -0000 --ey/N+yb7u/X9mFhi Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Dec 25, 2012 at 08:42:27PM +0000, Robert Watson wrote: > On Wed, 19 Dec 2012, Alan Cox wrote: >=20 > >> Are the machines that don't have a direct map performance critical? My= =20 > >> expectation is that they are legacy or embedded. This seems like a gr= eat=20 > >> project to do when the rest of the pieces are stable and fast. Until t= hen=20 > >> they could just use something like pbufs? > > > > I think the answer to your first question depends entirely on who you a= re.=20 > > :-) Also, at the low-end of the server space, there are many people tr= ying=20 > > to promote arm-based systems. While FreeBSD may never run on your arm-= based=20 > > phone, I think that ceding the arm-based server market to others will b= e a=20 > > strategic mistake. > > > > Alan > > > > P.S. I think we're moving the discussion to far away from kib's origina= l, so=20 > > I suggest changing the subject line on any follow ups. >=20 > Despite moving the discussion a little further away: MIPS-based > systems, a direct mapped map segment (e.g., kseg, xkphys, etc) is part > of the underlying design and doesn't rely on any TLB entries at all. > We run much of the kernel from direct map regions to avoid causing TLB > pressure. Yes, as it was noted already, 32bit mips kseg is not much usable on the mips systems with more than 1GB of RAM. But Alan' another patch, with, I believe, small modification, could provide the gain there too. --ey/N+yb7u/X9mFhi Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.19 (FreeBSD) iQIcBAEBAgAGBQJQ2hE2AAoJEJDCuSvBvK1BMRsP/jYntSnPvEg8THXL/XEou9Rj VwWQaVLH3GH5Tj4tZ7B6sQIsg3C9+fYVGA84LFCc/i9aa6aKZmBXTrHGB2ba5TX6 afd2kbIG0Bcn7MeAyLfy58OQUKA0wymmjGPMw/+0+6ZP0c+6vmO1mDMdy2MpWzKI QJpTYaBxwZeS3QroQKkj/l3BFS4sL3sz3QeVdt8Tg9JslbMCFxqWur+DKvRDq/g0 E1zLtS1qu/Zn00BewYlMxxOsBSQ+IbtZlGJtaWqu8+bdOGG+ns2sFQDy25Nxui0d UFFIfUXnjI33IYjDWVEcymk9lOeqDTylBhK2geuI3mzZtkM1JlVx9QPFO0SIT0WV Ci3PftF2SoVz47ogeHBkzy3BUU/jyjU68uDx55p6JtOGvgrCH4mQ1h4ivpsOAZAg G7Xx1V9r10iNs6UIioX0U9lZ+bZmJoNkxH8A/G8eHhzqjqHx+Wr2AfnBQv/rcyM6 KRYqahLfr6PyTAfVpQ+LAD0azCB8FkL0jwADqSrxZakQDsIF1Kc26sZuEFO2HdeO rwO3hgKE8AAS/r0cRa0mGtf8xEfnI1gy3cUoYUF1CUJywxBGrKowm749lMAtaHak s38wPZfCxcSOPHwMVQykQeVB3UcDiXgvSvk9Ov15Raq6+zq2BA3OcW5I1ymlR25V 1nQdaatbyHdZ48p+U56r =+63G -----END PGP SIGNATURE----- --ey/N+yb7u/X9mFhi--