From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=37378 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1PZjTM-0000jH-Aj for qemu-devel@nongnu.org; Mon, 03 Jan 2011 07:25:13 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1PZjTK-000067-KY for qemu-devel@nongnu.org; Mon, 03 Jan 2011 07:25:12 -0500 Received: from mx1.redhat.com ([209.132.183.28]:59500) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1PZjTK-00005s-Do for qemu-devel@nongnu.org; Mon, 03 Jan 2011 07:25:10 -0500 Date: Mon, 3 Jan 2011 14:25:08 +0200 From: Gleb Natapov Subject: Re: [Qemu-devel] qemu vs. kvm: When to flush the coalesced mmio buffer? Message-ID: <20110103122507.GA23389@redhat.com> References: <4D21BCF4.6020904@web.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4D21BCF4.6020904@web.de> List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jan Kiszka Cc: qemu-devel , kvm 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.