From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dor Laor Subject: Re: recommended clock source Date: Mon, 03 Aug 2009 11:29:00 +0300 Message-ID: <4A769FCC.9070102@redhat.com> References: <4A768B3B.6050402@redhat.com> <4A769BC0.8010909@nagafix.co.uk> Reply-To: dlaor@redhat.com Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: Kent Tong , kvm@vger.kernel.org To: Antoine Martin Return-path: Received: from mx2.redhat.com ([66.187.237.31]:50727 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754164AbZHCIa7 (ORCPT ); Mon, 3 Aug 2009 04:30:59 -0400 In-Reply-To: <4A769BC0.8010909@nagafix.co.uk> Sender: kvm-owner@vger.kernel.org List-ID: On 08/03/2009 11:11 AM, Antoine Martin wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA512 > > Hi, > > Dor Laor wrote: >> On 08/03/2009 04:52 AM, Kent Tong wrote: >>> Hi, >>> >>> It seems to be an unsettled issue, but, would any kind soul suggest >>> the current >>> best practice for setting the clock in Ubuntu Linux and Windows guests? >> For Linux the best source clock is the kvm pv clock (exist from 2.6.27 >> and above). > # qemu-system-x86_64 -clock ? > Available alarm timers, in order of precedence: > dynticks > hpet > rtc > unix > > I see no "pv clock"... > Which one should I use then? > Did I miss a ./configure or .config option? No, we were talking about different clocks. I was explaining the guest source clock while you wanted some info for the host-qemu clock. You can use the default - dynticks. hpet and rtc might be good if you need a fine grain granularity on older < 2.6.24 host kernels. > > Cheers > Antoine > >> For windows, standard acpi HAL uses the rtc clock by default. As long as >> you use the -rtc-td-hack it won't drift. >> >> When the tsc is not stable on the host or the host cpu might get into >> deep sleep state (c2), you better use another source clock in the guest >> - for windows it should be the pmtimer (using the boot.ini). >> >>> Thanks! >>> >>> -- >>> To unsubscribe from this list: send the line "unsubscribe kvm" in >>> the body of a message to majordomo@vger.kernel.org >>> More majordomo info at http://vger.kernel.org/majordomo-info.html >> -- >> To unsubscribe from this list: send the line "unsubscribe kvm" in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html > -----BEGIN PGP SIGNATURE----- > Version: GnuPG v1.4.9 (GNU/Linux) > Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org > > iEYEAREKAAYFAkp2m8AACgkQGK2zHPGK1rtQmACeM7UQJZS8TqVjqixZANKBm2gJ > kzMAnAxNjQj73tgRyxhP99dpQ0CpWXLW > =HWG8 > -----END PGP SIGNATURE-----