From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: [patch 3/3] KVM: x86: add tracepoint to wait_lapic_expire Date: Tue, 16 Dec 2014 13:19:07 +0100 Message-ID: <5490233B.10109@redhat.com> References: <20141215220605.806000829@redhat.com> <20141215220917.035037123@redhat.com> <548FF56B.9020709@redhat.com> <20141216121556.GA28966@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 , Radim Krcmar To: Marcelo Tosatti Return-path: Received: from mx1.redhat.com ([209.132.183.28]:60878 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750835AbaLPMTM (ORCPT ); Tue, 16 Dec 2014 07:19:12 -0500 Received: from int-mx10.intmail.prod.int.phx2.redhat.com (int-mx10.intmail.prod.int.phx2.redhat.com [10.5.11.23]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id sBGCJC0j026045 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL) for ; Tue, 16 Dec 2014 07:19:12 -0500 In-Reply-To: <20141216121556.GA28966@amt.cnet> Sender: kvm-owner@vger.kernel.org List-ID: On 16/12/2014 13:15, Marcelo Tosatti wrote: > > Let's add guest_tsc - tsc_deadline to the tracepoint. This should > > simplify the tuning of the parameter. > > total_delay is very close to that, except the summands are > > 1000 + 1000 + ... + "remainder" > > Yes? Almost: guest_tsc - tsc_deadline will be negative if the vmentry overshot the original tsc_deadline. In that case, total_delay will be zero. > BTW its very easy to tune the parameter with the kvm-unit-test test > (the optimal value is clear). I'll write a document. Nice benefit of the test. :) Paolo