From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from [140.186.70.92] (port=41194 helo=eggs.gnu.org)
	by lists.gnu.org with esmtp (Exim 4.43) id 1OghEk-0002ay-Bx
	for qemu-devel@nongnu.org; Wed, 04 Aug 2010 12:54:39 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69)
	(envelope-from <avi@redhat.com>) id 1OghEj-0006Ol-4M
	for qemu-devel@nongnu.org; Wed, 04 Aug 2010 12:54:38 -0400
Received: from mx1.redhat.com ([209.132.183.28]:64855)
	by eggs.gnu.org with esmtp (Exim 4.69)
	(envelope-from <avi@redhat.com>) id 1OghEi-0006Og-PR
	for qemu-devel@nongnu.org; Wed, 04 Aug 2010 12:54:37 -0400
Message-ID: <4C599B45.6030808@redhat.com>
Date: Wed, 04 Aug 2010 19:54:29 +0300
From: Avi Kivity <avi@redhat.com>
MIME-Version: 1.0
Subject: Re: [Qemu-devel] Anyone seeing huge slowdown launching qemu with
	Linux 2.6.35?
References: <20100803190525.GB16570@redhat.com>
	<4C586AB9.5040302@codemonkey.ws> <4C586CF9.7030206@redhat.com>
	<4C588804.5060803@redhat.com> <4C590046.2020705@redhat.com>
	<4C591D48.9080301@redhat.com> <4C592218.3000901@redhat.com>
	<4C596549.1070109@codemonkey.ws>
	<20100804130709.GL10499@redhat.com>
	<4C5967D8.7080707@codemonkey.ws>
	<20100804133401.GP10499@redhat.com>
	<4C5970AC.6060105@codemonkey.ws> <4C5995B4.90505@redhat.com>
	<4C5996F4.6010205@redhat.com>
	<721C3046-D6A7-47B2-A18C-4E59F2B68797@suse.de>
In-Reply-To: <721C3046-D6A7-47B2-A18C-4E59F2B68797@suse.de>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
List-Id: qemu-devel.nongnu.org
List-Unsubscribe: <http://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.nongnu.org/archive/html/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <http://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: Alexander Graf <agraf@suse.de>
Cc: Gleb Natapov <gleb@redhat.com>, kvm@vger.kernel.org, qemu-devel@nongnu.org, "Richard W.M. Jones" <rjones@redhat.com>, Gerd Hoffmann <kraxel@redhat.com>

  On 08/04/2010 07:45 PM, Alexander Graf wrote:
>
> I see two alternatives out of this mess:
>
> 1) Speed up string PIO so we're actually fast again.

Certainly, the best option given that it needs no new interfaces, and 
improves the most workloads.

> 2) Using a different interface (that could also be DMA fw_cfg - remember, we're on a private interface anyways)

A guest/host interface is not private.

> Admittedly 1 would also help in more cases than just booting with -kernel and -initrd, but if that won't get us to acceptable levels (and yes, 8 seconds for 100MB is unacceptable) I don't see any way around 2.

3) don't use -kernel for 100MB or more.  It's not the right tool.

-- 
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.