Date: Tue, 25 Dec 2012 22:48:54 +0200 From: Konstantin Belousov <kostikbel@gmail.com> To: Robert Watson <rwatson@freebsd.org> Cc: alc@freebsd.org, arch@freebsd.org, Alan Cox <alc@rice.edu> Subject: Re: Unmapped I/O Message-ID: <20121225204854.GE82219@kib.kiev.ua> In-Reply-To: <alpine.BSF.2.00.1212252040270.56707@fledge.watson.org> References: <20121219135451.GU71906@kib.kiev.ua> <CAJUyCcNuD_TWR6xxFxVqDi4-eBGx3Jjs21eBxaZYYVUERESbMw@mail.gmail.com> <alpine.BSF.2.00.1212190923170.2005@desktop> <50D22EA6.1040501@rice.edu> <alpine.BSF.2.00.1212252040270.56707@fledge.watson.org>
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--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--
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