From owner-freebsd-current@FreeBSD.ORG Sun Mar 29 18:22:23 2009 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 4ED751065676; Sun, 29 Mar 2009 18:22:23 +0000 (UTC) (envelope-from peterjeremy@optushome.com.au) Received: from mail36.syd.optusnet.com.au (mail36.syd.optusnet.com.au [211.29.133.76]) by mx1.freebsd.org (Postfix) with ESMTP id D0B6B8FC26; Sun, 29 Mar 2009 18:22:22 +0000 (UTC) (envelope-from peterjeremy@optushome.com.au) Received: from server.vk2pj.dyndns.org (c122-106-216-167.belrs3.nsw.optusnet.com.au [122.106.216.167]) by mail36.syd.optusnet.com.au (8.13.1/8.13.1) with ESMTP id n2TIMKND000444 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Mon, 30 Mar 2009 05:22:21 +1100 X-Bogosity: Ham, spamicity=0.000000 Received: from server.vk2pj.dyndns.org (localhost.vk2pj.dyndns.org [127.0.0.1]) by server.vk2pj.dyndns.org (8.14.3/8.14.3) with ESMTP id n2TIMKZU025407; Mon, 30 Mar 2009 05:22:20 +1100 (EST) (envelope-from peter@server.vk2pj.dyndns.org) Received: (from peter@localhost) by server.vk2pj.dyndns.org (8.14.3/8.14.3/Submit) id n2TIMK5Q025406; Mon, 30 Mar 2009 05:22:20 +1100 (EST) (envelope-from peter) Date: Mon, 30 Mar 2009 05:22:20 +1100 From: Peter Jeremy To: David Xu Message-ID: <20090329182219.GC38985@server.vk2pj.dyndns.org> References: <11609492.9579.1238167614335.JavaMail.root@vms070.mailsrvcs.net> <49CD0405.1060704@samsco.org> <49CD30E9.7030501@elischer.org> <49CEC261.4010803@freebsd.org> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="YD3LsXFS42OYHhNZ" Content-Disposition: inline In-Reply-To: <49CEC261.4010803@freebsd.org> X-PGP-Key: http://members.optusnet.com.au/peterjeremy/pubkey.asc User-Agent: Mutt/1.5.19 (2009-01-05) Cc: freebsd-hackers@freebsd.org, freebsd-current@freebsd.org, prashant.vaibhav@gmail.com Subject: Re: Improving the kernel/i386 timecounter performance (GSoC proposal) X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 29 Mar 2009 18:22:26 -0000 --YD3LsXFS42OYHhNZ Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On 2009-Mar-29 08:35:45 +0800, David Xu wrote: >Julian Elischer wrote: >> interestingly it is even feasible to have a per-thread page.. >> it requires that the scheduler change a page table entry tough. > >I will knock his door at midnight if he added such a heavy weight >task in the scheduler, TLB shutdown is horrible, and big code size >squeezing out data from CPU cache is not idea model. >scheduler should be as simple as just a context switching routine. If the TSC is not consistent between all cores (which is probably the most common situation at present), then using the TSC implies knowing which core you are executing on. From a userland perspective, the easiest way to do this is to have a page of data that varies depending on which core you are executing on. --=20 Peter Jeremy --YD3LsXFS42OYHhNZ Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.10 (FreeBSD) iEYEARECAAYFAknPvFsACgkQ/opHv/APuIeXKgCgviRrpnxRZFKKu/OZ8Q8LAt7d mOgAoIukrhlHkgJJmLZQMlFRBBO7yzbM =I94l -----END PGP SIGNATURE----- --YD3LsXFS42OYHhNZ--