Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756383AbYJIUqE (ORCPT ); Thu, 9 Oct 2008 16:46:04 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753844AbYJIUpy (ORCPT ); Thu, 9 Oct 2008 16:45:54 -0400 Received: from wa-out-1112.google.com ([209.85.146.177]:30840 "EHLO wa-out-1112.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753842AbYJIUpx (ORCPT ); Thu, 9 Oct 2008 16:45:53 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:to:subject:cc:in-reply-to:mime-version :content-type:content-transfer-encoding:content-disposition :references; b=UziBeP7UnB2DEBvUeuaOCFnBgRJOv1ed0rwjTeW5avZ9L59ORMhnSjVyulDmS2WucA MEYn9ZScPbVfy/md3ezBXUSbBgqS+Gxcfp/gKhxXWDpZplI3lu2o8XJJYOc5vd9NsHM2 AYT8YhEj9O3eVqSvVQE44EWDpsyM565eOcGUY= Message-ID: <35f686220810091345h253d71e8s4fe9d7ea8e636ccc@mail.gmail.com> Date: Thu, 9 Oct 2008 13:45:52 -0700 From: "Alok kataria" To: "Thomas Gleixner" Subject: Re: [PATCH] Re: x86_32 tsc/pit and hrtimers Cc: "Jeff Hansen" , "Chris Snook" , torvalds@linux-foundation.org, linux-kernel@vger.kernel.org, mingo@elte.hu, akataria@vmware.com In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <48ED1728.5060708@redhat.com> <48ED2A89.3000902@redhat.com> <48EE4FC4.7070902@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1650 Lines: 42 On Thu, Oct 9, 2008 at 12:53 PM, Thomas Gleixner wrote: > On Thu, 9 Oct 2008, Jeff Hansen wrote: > >> OK, so are we all agreed that something like clocksource_trust=tsc would be >> the best? > > No, it's per affected device: tsc=trust or tsc=stable or whatever > unintuitive name we want to come up. And it is a modification to TSC > not to the clocksource layer. Yep, this is cool. I too have a patch in my local tree which does a similar thing i have a tsc_reliable flag which is set right now only when we are running under a VMware hypervisor. Along with marking the no_verify flag for TSC, this patch of mine also skips the TSC synchornization checks. The TSC synchronization loop which is run whenever a new cpu is brought up is not actually needed on systems which are known to have a reliable TSC. TSC between 2 cpus can be off by a marginal value on such systems and thats okay for timekeeping, since we do check for tsc going back in read_tsc. Can this reasoning be included and synchronization skipped for all these systems with reliable aka trustworthy TSC's ? Thanks, Alok > > Thanks, > > tglx > -- > 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/ > -- 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/