From owner-freebsd-current@FreeBSD.ORG Fri Mar 27 18:46:47 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 9A2951065677 for ; Fri, 27 Mar 2009 18:46:47 +0000 (UTC) (envelope-from pisymbol@gmail.com) Received: from an-out-0708.google.com (an-out-0708.google.com [209.85.132.245]) by mx1.freebsd.org (Postfix) with ESMTP id 506D38FC25 for ; Fri, 27 Mar 2009 18:46:47 +0000 (UTC) (envelope-from pisymbol@gmail.com) Received: by an-out-0708.google.com with SMTP id d11so755105and.13 for ; Fri, 27 Mar 2009 11:46:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:in-reply-to:references :date:message-id:subject:from:to:cc:content-type :content-transfer-encoding; bh=072cPdOVo+jrqhu6xN2dVesAoBG6ikaFPu8DMD8VXcE=; b=NFDVoB1nHsH6GaSbmGgWlHoEmrgN46+9ZSQJna81iBGVKo6hXj5O2XF6PaC8Grtusj fLxgcUX3gwoa6QBP3jFzcJJ6zgq+jhd8ITqFSU8p7kEus6+xFpGaAaund4VVgIQMkRkI x7UgLAlV5Pb80skiv8Lmi6TM4KPMqz8S9v/cA= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=ngb6e3gvarjINEVcT+8t4pUnOR9TbWzF3VNcJEP8puWapfyYy0BBW55cRRF8gf1LlR 6UExbOIB1rKt9QAVQYyWs53V2gm9S0ZFc7dgIIqWiUflSfreyDBWGO4iuQoWSMIsTQl3 BUiDYybeFeLu26dZaRVME6up7W26x1UgzDCQg= MIME-Version: 1.0 Received: by 10.100.206.14 with SMTP id d14mr2020519ang.67.1238177956676; Fri, 27 Mar 2009 11:19:16 -0700 (PDT) In-Reply-To: <5739.1238175087@critter.freebsd.dk> References: <49CD0405.1060704@samsco.org> <5739.1238175087@critter.freebsd.dk> Date: Fri, 27 Mar 2009 14:19:16 -0400 Message-ID: <3c0b01820903271119l4161c7b8yf74613b184add487@mail.gmail.com> From: Alexander Sack To: FreeBSD Hackers Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Cc: attilio@freebsd.org, Sergey Babkin , prashant.vaibhav@gmail.com, freebsd-current@freebsd.org 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: Fri, 27 Mar 2009 18:46:47 -0000 On Fri, Mar 27, 2009 at 1:31 PM, Poul-Henning Kamp wro= te: > In message <49CD0405.1060704@samsco.org>, Scott Long writes: > >>I've been talking about this for years. =A0All I need is help with the VM >>magic to create the page on fork. =A0I also want two pages, one global >>for gettimeofday (and any other global data we can think of) and one >>per-process for static data like getpid/getgid. > > Agreed, that is a good place to start. I'm assuming folks are still in love with the TSC because it still the cheapest as oppose ACPI-fast or HPET to even contemplate this? Also I thought at least PHK's comment (Sergey mentioned it) was true regardless of bus, that the TSC is not consistent across multiple packages (and for that matter I suppose cores) due to I *think* its ISA lineage so how does this work again? Won't the rate in which you tick up be sporadic over the course of the process scheduled on different cores? (i.e. depending on what core RDTSC happened to land on) -aps