From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932088AbVIZWH2 (ORCPT ); Mon, 26 Sep 2005 18:07:28 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932345AbVIZWH2 (ORCPT ); Mon, 26 Sep 2005 18:07:28 -0400 Received: from mxfep02.bredband.com ([195.54.107.73]:19702 "EHLO mxfep02.bredband.com") by vger.kernel.org with ESMTP id S932088AbVIZWH2 (ORCPT ); Mon, 26 Sep 2005 18:07:28 -0400 Message-ID: <4338731B.4020301@stesmi.com> Date: Tue, 27 Sep 2005 00:15:55 +0200 From: Stefan Smietanowski User-Agent: Mozilla Thunderbird 1.0.2 (Windows/20050317) X-Accept-Language: en-us, en MIME-Version: 1.0 To: john stultz CC: Andrew Morton , Andi Kleen , lkml Subject: Re: [PATCH] x86-64: Fix bad assumption that dualcore cpus have synced TSCs (resend) References: <1127764012.8195.138.camel@cog.beaverton.ibm.com> In-Reply-To: <1127764012.8195.138.camel@cog.beaverton.ibm.com> X-Enigmail-Version: 0.92.0.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-AntiVirus: checked by Vexira Milter 1.0.7; VAE 6.29.0.5; VDF 6.29.0.100 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Hi John. > This patch should resolve the issue seen in bugme bug #5105, where it > is assumed that dualcore x86_64 systems have synced TSCs. This is not > the case, and alternate timesources should be used instead. > > For more details, see: > http://bugzilla.kernel.org/show_bug.cgi?id=5105 > > Andi's earlier concerns that the TSCs should be synced on dualcore > systems have been resolved by confirmation from AMD folks that they can > be unsynced. > > Please consider for inclusion in your tree. Wouldn't it be a good idea to change the comment following the code you removed as well? Why have a comment saying "multi socket systems" if there is no distinction anymore? > > diff --git a/arch/x86_64/kernel/time.c b/arch/x86_64/kernel/time.c > --- a/arch/x86_64/kernel/time.c > +++ b/arch/x86_64/kernel/time.c > @@ -959,9 +959,6 @@ static __init int unsynchronized_tsc(voi > are handled in the OEM check above. */ > if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL) > return 0; > - /* All in a single socket - should be synchronized */ > - if (cpus_weight(cpu_core_map[0]) == num_online_cpus()) > - return 0; > #endif > /* Assume multi socket systems are not synchronized */ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ > return num_online_cpus() > 1; // Stefan -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.1 (MingW32) iD8DBQFDOHMbBrn2kJu9P78RAnSlAKCE2NSTYbi553i0OGadmRfuMdD3hgCgwedE blCF8zdC+fuTOgIuBy1Af60= =T4tA -----END PGP SIGNATURE-----