From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751485AbbAMIOp (ORCPT ); Tue, 13 Jan 2015 03:14:45 -0500 Received: from mail-wg0-f43.google.com ([74.125.82.43]:51944 "EHLO mail-wg0-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751065AbbAMIOo (ORCPT ); Tue, 13 Jan 2015 03:14:44 -0500 From: Imre Palik To: xen-devel@lists.xenproject.org, David Vrabel Cc: Konrad Rzeszutek Wilk , Boris Ostrovsky , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org, linux-kernel@vger.kernel.org, "Palik, Imre" , Anthony Liguori Subject: [PATCH] xen-time: decreasing the rating of the xen clocksource below that of the tsc clocksource for dom0's Date: Tue, 13 Jan 2015 09:14:22 +0100 Message-Id: <1421136862-15083-1-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. This patch decreases the rating of the Xen clocksource in Dom0s to 275. Which is half-way between the rating of the TSC clocksource (300) and the hpet clocksource (250). 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