Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S966213AbWKNRGU (ORCPT ); Tue, 14 Nov 2006 12:06:20 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S966214AbWKNRGU (ORCPT ); Tue, 14 Nov 2006 12:06:20 -0500 Received: from elvis.mu.org ([192.203.228.196]:11249 "EHLO elvis.mu.org") by vger.kernel.org with ESMTP id S966213AbWKNRGT (ORCPT ); Tue, 14 Nov 2006 12:06:19 -0500 Message-ID: <4559F781.6020607@FreeBSD.org> Date: Tue, 14 Nov 2006 09:06:09 -0800 From: Suleiman Souhlal User-Agent: Mozilla Thunderbird 1.0.7 (X11/20051204) X-Accept-Language: en-us, en MIME-Version: 1.0 To: Shem Multinymous CC: Andi Kleen , Linux Kernel ML , vojtech@suse.cz, Jiri Bohac , Nigel Cunningham , Pavel Machek Subject: Re: [PATCH 0/2] Make the TSC safe to be used by gettimeofday(). References: <455916A5.2030402@FreeBSD.org> <200611140250.57160.ak@suse.de> <45592497.1080109@FreeBSD.org> <41840b750611140430k3b46023dr9a01b8b38bbb535d@mail.gmail.com> In-Reply-To: <41840b750611140430k3b46023dr9a01b8b38bbb535d@mail.gmail.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1153 Lines: 26 Shem Multinymous wrote: > On 11/14/06, Suleiman Souhlal wrote: > >> I believe that the results returned will always be monotonic, as long as >> the frequency of the TSC does not change from under us (that is, without >> the kernel knowing). This is because we "synchronize" each CPU's vxtime >> with a global time source (HPET) every time we know the TSC rate changes. > > > Does this hold after a suspend/resume cycle? You could be resuming > with a different CPU clock than what you suspended with, and I'm not > sure anything guarantees an early enough re-sync. I have to admit that I didn't really design this patch with suspend/resume in mind, and that I'm not too familiar with how they work. Do the HPET/ACPI timers still run while the system is suspended? If not, there shouldn't be any problem, as long as the kernel is informed of the resume early enough. -- Suleiman - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/