From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754054AbbAGQRw (ORCPT ); Wed, 7 Jan 2015 11:17:52 -0500 Received: from mail-wg0-f45.google.com ([74.125.82.45]:45557 "EHLO mail-wg0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753859AbbAGQRu (ORCPT ); Wed, 7 Jan 2015 11:17:50 -0500 From: Imre Palik To: xen-devel@lists.xenproject.org Cc: Konrad Rzeszutek Wilk , Boris Ostrovsky , David Vrabel , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org, linux-kernel@vger.kernel.org, "Palik, Imre" , Anthony Liguori Subject: [PATCH RFC] xen-time: decreasing the rating of the xen clocksource below that of the tsc clocksource for dom0's Date: Wed, 7 Jan 2015 17:16:38 +0100 Message-Id: <1420647398-20207-1-git-send-email-imrep.amz@gmail.com> X-Mailer: git-send-email 1.7.9.5 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Palik, Imre" In Dom0's the use of the TSC clocksource (whenever it is stable enough to be used) instead of the Xen clocksource should not cause any issues, as Dom0 VMs never live-migrated. The TSC clocksource is somewhat more efficient than the Xen paravirtualised clocksource, thus it should have higher rating. Cc: Anthony Liguori Signed-off-by: Imre Palik --- arch/x86/xen/time.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c index f473d26..c768726 100644 --- a/arch/x86/xen/time.c +++ b/arch/x86/xen/time.c @@ -487,6 +487,10 @@ static void __init xen_time_init(void) int cpu = smp_processor_id(); struct timespec tp; + /* As Dom0 is never moved, no penalty on using TSC there */ + if (xen_initial_domain()) + xen_clocksource.rating = 275; + clocksource_register_hz(&xen_clocksource, NSEC_PER_SEC); if (HYPERVISOR_vcpu_op(VCPUOP_stop_periodic_timer, cpu, NULL) == 0) { -- 1.7.9.5