From owner-freebsd-arch@FreeBSD.ORG Sun Jan 13 23:18:38 2013 Return-Path: Delivered-To: freebsd-arch@freebsd.org Received: from mx1.freebsd.org (mx1.FreeBSD.org [8.8.178.115]) by hub.freebsd.org (Postfix) with ESMTP id 0C93A18D; Sun, 13 Jan 2013 23:18:38 +0000 (UTC) (envelope-from mavbsd@gmail.com) Received: from mail-ea0-f175.google.com (mail-ea0-f175.google.com [209.85.215.175]) by mx1.freebsd.org (Postfix) with ESMTP id 4BD4461E; Sun, 13 Jan 2013 23:18:37 +0000 (UTC) Received: by mail-ea0-f175.google.com with SMTP id d1so300707eab.6 for ; Sun, 13 Jan 2013 15:18:36 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=x-received:sender:message-id:date:from:user-agent:mime-version:to :cc:subject:references:in-reply-to:content-type :content-transfer-encoding; bh=GC8+rsuCb6k06K5jKC3zmOB0/sW2RHVaHFU6jwa6lrc=; b=iXLR8FWA1PNxzBvUMhT/VpU7Q1HYGwF9WvzAYltyiNOLEBWvSUIogIROHUrCuWR1KP SgtxmVUlocCKMb6sYb0TCEf+Be4lloq9J2smJVLR+7wgsg1aqnEWU6T3L7fWtw2JpyiM LbuBjUEcy/EwMT5pxBmCVZOxLDtTXUC7MVKZY7LDmQucSzq634Rdtz9HrNOH24ly4pPd xZc4k6T+/U7fcB9WiI/xAfJtEgP9Nj5Nww/fLuKKtvqQLaTmi8sXUHEYjGF3gzFVPwPs lSmsyNJTbVEriz+T+4fWJg8sZnzTbn+DaG3YDQ7t7bZynnieY8ebHkfCsvpOeM0JK8Qh lbdg== X-Received: by 10.14.219.72 with SMTP id l48mr225048018eep.37.1358119116209; Sun, 13 Jan 2013 15:18:36 -0800 (PST) Received: from mavbook.mavhome.dp.ua (mavhome.mavhome.dp.ua. [213.227.240.37]) by mx.google.com with ESMTPS id f49sm19300520eep.12.2013.01.13.15.18.34 (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Sun, 13 Jan 2013 15:18:35 -0800 (PST) Sender: Alexander Motin Message-ID: <50F340C8.2040905@FreeBSD.org> Date: Mon, 14 Jan 2013 01:18:32 +0200 From: Alexander Motin User-Agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:17.0) Gecko/17.0 Thunderbird/17.0 MIME-Version: 1.0 To: Ian Lepore Subject: Re: [RFC/RFT] calloutng References: <50CCAB99.4040308@FreeBSD.org> <50CE5B54.3050905@FreeBSD.org> <50D03173.9080904@FreeBSD.org> <20121225232126.GA47692@alchemy.franken.de> <50DB4EFE.2020600@FreeBSD.org> <20130106152313.GD26039@alchemy.franken.de> <50EBF921.2000304@FreeBSD.org> <20130113180940.GM26039@alchemy.franken.de> <50F30CAB.3000001@FreeBSD.org> <1358118601.32417.41.camel@revolution.hippie.lan> In-Reply-To: <1358118601.32417.41.camel@revolution.hippie.lan> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Davide Italiano , freebsd-arch@freebsd.org, FreeBSD Current , Marius Strobl 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: Sun, 13 Jan 2013 23:18:38 -0000 On 14.01.2013 01:10, Ian Lepore wrote: > On Sun, 2013-01-13 at 21:36 +0200, Alexander Motin wrote: >> On 13.01.2013 20:09, Marius Strobl wrote: > [...] >>> >>> Uhm, there are no NMIs on sparc64. Does it make sense to bypass this >>> adjustment on sparc64? >> >> If it is not possible or not good to to stop timer during programming, >> there will always be some race window between code execution and timer >> ticking. So some minimal safety range should be reserved. Though it >> probably can be significantly reduced. In case of x86/HPET there is >> additional factor of NMI, that extends race to unpredictable level and >> so makes additional post-read almost mandatory. >> >>>> May be with rereading counter >>>> after programming comparator (same as done for HPET, reading which is >>>> probably much more expensive) this value could be reduced. >>> >>> I see. There are some bigger fish to fry at the moment though :) >> > > Speaking of the HPET code, it seems to me that its restart logic can > fire the same event twice. Is that harmless? It is much less harmful then not fire and loose interrupt completely, and as result stuck for indefinite time. I have no better ideas, while this seems works well. -- Alexander Motin