From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [RFC][PATCH] qemu-kvm: Introduce writeback scope for cpu_synchronize_state Date: Mon, 16 Nov 2009 21:14:15 +0200 Message-ID: <4B01A487.3020808@redhat.com> References: <4B018542.3020602@siemens.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: Marcelo Tosatti , kvm , Gleb Natapov To: Jan Kiszka Return-path: Received: from mx1.redhat.com ([209.132.183.28]:8658 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751024AbZKPTOS (ORCPT ); Mon, 16 Nov 2009 14:14:18 -0500 In-Reply-To: <4B018542.3020602@siemens.com> Sender: kvm-owner@vger.kernel.org List-ID: On 11/16/2009 07:00 PM, Jan Kiszka wrote: > This patch aims at addressing the mp_state writeback issue in a cleaner > fashion. What's the issue? the fact that mp_state is updated whenever state is synchronized, while it could be simultaneously updated from other vcpus (which latter updates are then lost)? > By introducing additional information about the scope of the > scheduled vcpu state writeback, we can simply skin mp_state (and maybe > other specific states in the future) when updating the in-kernel state. > > The writeback scope is defined when calling cpu_synchronize_state. It > accumulated, ie. once a full writeback was requested, this will stick > until it was performed. > Maybe it's just simpler to divorce mp_state from the rest of the state. -- Do not meddle in the internals of kernels, for they are subtle and quick to panic.