From mboxrd@z Thu Jan  1 00:00:00 1970
From: Gleb Natapov <gleb@redhat.com>
Subject: Re: [Qemu-devel] qemu vs. kvm: When to flush the coalesced mmio
 buffer?
Date: Mon, 3 Jan 2011 14:25:08 +0200
Message-ID: <20110103122507.GA23389@redhat.com>
References: <4D21BCF4.6020904@web.de>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Cc: kvm <kvm@vger.kernel.org>, qemu-devel <qemu-devel@nongnu.org>
To: Jan Kiszka <jan.kiszka@web.de>
Return-path: <kvm-owner@vger.kernel.org>
Received: from mx1.redhat.com ([209.132.183.28]:16008 "EHLO mx1.redhat.com"
	rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
	id S1752623Ab1ACMZK (ORCPT <rfc822;kvm@vger.kernel.org>);
	Mon, 3 Jan 2011 07:25:10 -0500
Content-Disposition: inline
In-Reply-To: <4D21BCF4.6020904@web.de>
Sender: kvm-owner@vger.kernel.org
List-ID: <kvm.vger.kernel.org>

On Mon, Jan 03, 2011 at 01:11:32PM +0100, Jan Kiszka wrote:
> Hi again,
> 
> another subtle difference between qemu-kvm and upstream:
> 
> When we leave the guest for an IO window (KVM_RUN returns EINTR or
> EAGAIN), we call kvm_flush_coalesced_mmio_buffer in qemu-kvm but not in
> upstream. When version is better? I can't find any rationales in both
> git logs.
> 
Since coalesced mmio is used to prevent unnecessary exits to userspace
if vcpu thread is already in userspace why not flush coalesced mmio
buffer?

--
			Gleb.