From mboxrd@z Thu Jan  1 00:00:00 1970
From: Avi Kivity <avi@cloudius-systems.com>
Subject: Re: [Qemu-devel] [RFC] create a single workqueue for each vm to update
 vm irq routing table
Date: Tue, 26 Nov 2013 17:35:19 +0200
Message-ID: <5294BFB7.2090202@cloudius-systems.com>
References: <D3E216785288A145B7BC975F83A2ED10448ADCCB@SZXEMA510-MBS.china.huawei.com> <52949847.6020908@redhat.com> <CAEbWaipAnmoa=gMbB1aNb=btU6LgYXhcnmQWHJ_89m4yvw6Dug@mail.gmail.com> <5294A68F.6060301@redhat.com> <CAF950W+-UiX6xv4vYmnxji9aWDU8ds2rnx7JugnbHQWJdCCD-Q@mail.gmail.com> <5294B461.5000405@redhat.com> <5294B634.4050801@cloudius-systems.com> <20131126150357.GA20352@redhat.com> <5294BC3B.6070902@redhat.com> <5294BD61.7080904@cloudius-systems.com> <5294BE22.7040105@redhat.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Cc: Gleb Natapov <gleb@redhat.com>, Avi Kivity <avi.kivity@gmail.com>,
	"Huangweidong (C)" <weidong.huang@huawei.com>,
	KVM <kvm@vger.kernel.org>, "Michael S. Tsirkin" <mst@redhat.com>,
	"Jinxin (F)" <jinxin712@huawei.com>,
	"Zhanghaoyu (A)" <haoyu.zhang@huawei.com>,
	Luonengjun <luonengjun@huawei.com>,
	"qemu-devel@nongnu.org" <qemu-devel@nongnu.org>,
	Zanghongyong <zanghongyong@huawei.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Return-path: <kvm-owner@vger.kernel.org>
Received: from mail-bk0-f46.google.com ([209.85.214.46]:59215 "EHLO
	mail-bk0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S932190Ab3KZPfX (ORCPT <rfc822;kvm@vger.kernel.org>);
	Tue, 26 Nov 2013 10:35:23 -0500
Received: by mail-bk0-f46.google.com with SMTP id u15so2648882bkz.19
        for <kvm@vger.kernel.org>; Tue, 26 Nov 2013 07:35:22 -0800 (PST)
In-Reply-To: <5294BE22.7040105@redhat.com>
Sender: kvm-owner@vger.kernel.org
List-ID: <kvm.vger.kernel.org>

On 11/26/2013 05:28 PM, Paolo Bonzini wrote:
> Il 26/11/2013 16:25, Avi Kivity ha scritto:
>>> If we want to ensure, we need to use a different mechanism for
>>> synchronization than the global RCU.  QRCU would work; readers are not
>>> wait-free but only if there is a concurrent synchronize_qrcu, which
>>> should be rare.
>> An alternative path is to convince ourselves that the hardware does not
>> provide the guarantees that the current code provides, and so we can
>> relax them.
> No, I think it's a reasonable guarantee to provide.
>

Why?