From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: [patch 2/3] KVM: x86: add option to advance tscdeadline hrtimer expiration Date: Tue, 23 Dec 2014 14:18:03 +0100 Message-ID: <54996B8B.2090504@redhat.com> References: <20141216140813.493421022@redhat.com> <20141216140853.687723255@redhat.com> <20141217145805.GA29368@potion.brq.redhat.com> <20141217174139.GA31721@amt.cnet> <20141217193626.GA3082@potion.brq.redhat.com> <20141218122440.GA15896@amt.cnet> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org, Luiz Capitulino , Rik van Riel To: Marcelo Tosatti , Radim Krcmar Return-path: Received: from mail-wg0-f45.google.com ([74.125.82.45]:40190 "EHLO mail-wg0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751149AbaLWNSJ (ORCPT ); Tue, 23 Dec 2014 08:18:09 -0500 Received: by mail-wg0-f45.google.com with SMTP id b13so9004997wgh.32 for ; Tue, 23 Dec 2014 05:18:08 -0800 (PST) In-Reply-To: <20141218122440.GA15896@amt.cnet> Sender: kvm-owner@vger.kernel.org List-ID: On 18/12/2014 13:24, Marcelo Tosatti wrote: > True. I can change to a direct wait if that is preferred. What about this: guest_tsc = kvm_x86_ops->read_l1_tsc(vcpu, native_read_tsc()); trace_kvm_wait_lapic_expire(vcpu->vcpu_id, guest_tsc - tsc_deadline); /* We know that __delay is delay_tsc, see kvm_timer_init. */ if (guest_tsc < tsc_deadline) __delay(tsc_deadline - guest_tsc); and a check in kvm_timer_init: if (check_tsc_unstable() && lapic_timer_advance_ns) { pr_info("kvm: unstable TSC, disabling lapic_timer_advance_ns\n"); lapic_timer_advance_ns = 0; } Paolo