From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: [v3 13/26] KVM: Define a new interface kvm_find_dest_vcpu() for VT-d PI Date: Fri, 09 Jan 2015 15:56:00 +0100 Message-ID: <54AFEC00.80507@redhat.com> References: <1418397300-10870-1-git-send-email-feng.wu@intel.com> <1418397300-10870-14-git-send-email-feng.wu@intel.com> <20150109145435.GA22469@potion.brq.redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, x86@kernel.org, gleb@kernel.org, dwmw2@infradead.org, joro@8bytes.org, alex.williamson@redhat.com, jiang.liu@linux.intel.com, eric.auger@linaro.org, linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, kvm@vger.kernel.org To: =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , Feng Wu Return-path: Received: from mx1.redhat.com ([209.132.183.28]:58553 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754583AbbAIO4r (ORCPT ); Fri, 9 Jan 2015 09:56:47 -0500 In-Reply-To: <20150109145435.GA22469@potion.brq.redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On 09/01/2015 15:54, Radim Kr=C4=8Dm=C3=A1=C5=99 wrote: > There are two points relevant to this patch in new KVM's implementati= on, > ("KVM: x86: amend APIC lowest priority arbitration", > https://lkml.org/lkml/2015/1/9/362) >=20 > 1) lowest priority depends on TPR > 2) there is no need for balancing >=20 > (1) has to be considered with PI as well. The chipset doesn't support it. :( > I kept (2) to avoid whining from people building on that behaviour, b= ut > lowest priority backed by PI could be transparent without it. >=20 > Patch below removes the balancing, but I am not sure this is a price = we > allowed ourselves to pay ... what are your opinions? I wouldn't mind, but it requires a lot of benchmarking. Paolo