From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751632AbeEEIg4 (ORCPT ); Sat, 5 May 2018 04:36:56 -0400 Received: from mout.web.de ([212.227.17.12]:50687 "EHLO mout.web.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750830AbeEEIgk (ORCPT ); Sat, 5 May 2018 04:36:40 -0400 Subject: Re: [PATCH v2] KVM: X86: Limit timer frequency to 200ms To: Wanpeng Li , LKML , kvm Cc: Paolo Bonzini , =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , Anthoine Bourgeois , Darren Kenny References: <1525131328-27086-1-git-send-email-wanpengli@tencent.com> From: Jan Kiszka Openpgp: preference=signencrypt Message-ID: <96fca559-9759-0c2f-6e3b-98877c7340d3@web.de> Date: Sat, 5 May 2018 10:36:23 +0200 User-Agent: Mozilla/5.0 (X11; U; Linux i686 (x86_64); de; rv:1.8.1.12) Gecko/20080226 SUSE/2.0.0.12-1.1 Thunderbird/2.0.0.12 Mnenhy/0.7.5.666 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit X-Provags-ID: V03:K1:joWdx8OweVHXlcqJg+lZJxlAmjjcsHtlc3+Uh0cUA02V8fn+1EN Z28hlhjj8ox1eJnmMxBGB18y9XPAFxFSYIp/w4X/LEMcGFzYjHv2bn1f1QkXbbfhrRDhILp 9EaFvpeSNW7P5tHz9ehoTiix39k8VScUPrHQH3hmDJXVvHiNinTxpmHUicjRXKhFmzLBgZD yEfKwya0blKw8Xv08twUg== X-UI-Out-Filterresults: notjunk:1;V01:K0:DwwnOmW4694=:vdf9Ef1hj8PXkPU+ypPMNt jvQY/zqAAJIzXyZ8PjBMyq4l4Qh3Rm8eUMa0PVAw4W2Gf39QfFxdEUwVW99nXZCQ+fuZy19zR hnRJ63MKjtNSdX3XuFRLCZ40xj/xy4dxfKP2wCH2HfsdqBSo95MP5oIqR0pfRkN6ZFMDGt1ah kobWdcGP5dslCVVVUrixBQf91PF2VowrO9ZGY/P425GEe3gMLe0YY3Z7l/iGaeOTYbT6AluOm jz6o0E07JA+sAh/z8AqWNA+tJ0Qnqr6ECBwFn94WVX4BAGozidYcFSoNQFrnn+rRTEG5dWtwI GK1KUJO9DkMN1A3g9i4qf2LVKLcqjR+IQPHzwLhRRVFca16Y6ik2uryL43WZUPB3k/AJqaQ7I IONzrDw+eoZQ7cO8Czg6zzpEaOIKt5feS6WrFHnG+xczjgp528VMrK83ntS9oSzf+67taJhan LMUXKZTojJfBGkR7snEKxHZtAGA28QgKZ06TJ2JilpTAcHvdlxBodIRXyRCjD/Wkd8fIrUWGF pnmitrjakaj58M0hNpgiKqnzOHF+3tz8JAqByPcMhN6Ya8Y8WsDB2XGc8nokv3o3iWyRzAro6 DSSta9RonkSHWrrarjfHFk/W7VJDaQfz6BdM8+4RLEaZ92+6SPTZnB8qY6yGrR8oL/KlGxlbR 7TplA8sgN/NyQvTHwBYR7+vEN9esHOBXCYrToMJqDd2UmikfQw+aluOSVGzmjbRL6SKkdU4/3 9Cs8IL4UdUPVzWl1g6fRYd845tO5UdFZ1A+MyWCNIM6MH7r4SbLGKKDYE0LmWlAdRqgnNgsYp 6nLZE1J Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2018-05-05 01:44, Wanpeng Li wrote: > ping, > 2018-05-01 7:35 GMT+08:00 Wanpeng Li : >> From: Wanpeng Li >> >> Anthoine reported: >> The period used by Windows change over time but it can be 1 milliseconds >> or less. I saw the limit_periodic_timer_frequency print so 500 >> microseconds is sometimes reached. >> >> As suggested by Paolo, lower the timer frequency limit to a >> smaller interval of 200 ms (5000 Hz) to leave some headroom. This >> is required due to Windows 10 changing the scheduler tick limit >> from 1024 Hz to 2048 Hz. "... lower the *default* timer frequency limit to a smaller interval of 200 *us* ..." - same for the subject. (Amazing that even Windows 10 still uses periodic ticks.) Jan >> >> Reported-by: Anthoine Bourgeois >> Suggested-by: Paolo Bonzini >> Reviewed-by: Darren Kenny >> Cc: Paolo Bonzini >> Cc: Radim Krčmář >> Cc: Anthoine Bourgeois >> Cc: Darren Kenny >> Signed-off-by: Wanpeng Li >> --- >> v1 -> v2: >> * update patch subject and description >> >> arch/x86/kvm/x86.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c >> index 51ecd38..dc47073 100644 >> --- a/arch/x86/kvm/x86.c >> +++ b/arch/x86/kvm/x86.c >> @@ -114,7 +114,7 @@ module_param(ignore_msrs, bool, S_IRUGO | S_IWUSR); >> static bool __read_mostly report_ignored_msrs = true; >> module_param(report_ignored_msrs, bool, S_IRUGO | S_IWUSR); >> >> -unsigned int min_timer_period_us = 500; >> +unsigned int min_timer_period_us = 200; >> module_param(min_timer_period_us, uint, S_IRUGO | S_IWUSR); >> >> static bool __read_mostly kvmclock_periodic_sync = true; >> -- >> 2.7.4 >> >