From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gerd Hoffmann Subject: Re: [PATCH] tsc: use kvmclock for calibration Date: Thu, 09 Aug 2012 16:18:32 +0200 Message-ID: <5023C6B8.4090805@redhat.com> References: <1344513463-7329-1-git-send-email-kraxel@redhat.com> <5023B2C4.90302@redhat.com> <5023C1D2.5090103@redhat.com> <5023C2BE.5070702@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: seabios@seabios.org, kvm@vger.kernel.org To: Avi Kivity Return-path: Received: from mx1.redhat.com ([209.132.183.28]:21979 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030188Ab2HIOSp (ORCPT ); Thu, 9 Aug 2012 10:18:45 -0400 In-Reply-To: <5023C2BE.5070702@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: Hi, >> So what do you suggest? The options I see are: >> >> (1) Use this patch (with alignment issue fixed of course). >> (2) Do a full kvmclock implementation. Feels a bit like overkill. >> (3) SeaBIOS can fallback to the PIT for timing on machines which >> have no TSC. We could do that too in case we detect kvm ... > > What sort of timeouts are these? If seconds, maybe the rtc would be best. All sorts of timeouts, from a few miliseconds to seconds. The problematic ones are the longer timeouts, which wait for I/O stuff like disk reads complete. The stuff with smaller timeouts (like waiting for AHCI link become ready) tend to finish instantly in kvm. cheers, Gerd