From mboxrd@z Thu Jan  1 00:00:00 1970
From: Gerd Hoffmann <kraxel@redhat.com>
Subject: Re: assigned EHCI USB headset not working
Date: Fri, 10 Jun 2011 08:23:13 +0200
Message-ID: <4DF1B851.10609@redhat.com>
References: <4DEF17C1.7000805@web.de> <4DEF6FC9.8040209@redhat.com> <4DF065E9.4070605@web.de> <4DF06DED.7030604@web.de> <4DF07182.3060003@web.de> <4DF07218.7000903@web.de> <alpine.LNX.2.00.1106091913020.1476@linmac> <4DF0E5B0.8030704@siemens.com> <alpine.LNX.2.00.1106092007270.2172@linmac> <4DF0FEB4.6010109@siemens.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Cc: malc <av1474@comtv.ru>,
	=?ISO-8859-1?Q?Andr=E9_Weidemann?= <Andre.Weidemann@web.de>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
	qemu-devel <qemu-devel@nongnu.org>
To: Jan Kiszka <jan.kiszka@siemens.com>
Return-path: <kvm-owner@vger.kernel.org>
Received: from mx1.redhat.com ([209.132.183.28]:36008 "EHLO mx1.redhat.com"
	rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
	id S1751130Ab1FJGX3 (ORCPT <rfc822;kvm@vger.kernel.org>);
	Fri, 10 Jun 2011 02:23:29 -0400
In-Reply-To: <4DF0FEB4.6010109@siemens.com>
Sender: kvm-owner@vger.kernel.org
List-ID: <kvm.vger.kernel.org>

   Hi,

> I've two scenarios at hand now: one involves a Windows 7 guest with
> -soundhw hda, the other is my Musicpal (do you still have a firmware
> image at hand?). Some Linux guest here with identical configuration like
> Win7 does not show any problems in polling mode.

Noteworthy difference between linux and windows 7:  Windows 7 uses a 
pretty small ring buffer (~ one page, where 20ms sound data fit in) 
whereas linux uses *alot* more, 128k or so.

That makes win7 guests quite sensitive to latency issues, be it in the 
audio subsystem or elsewhere.  For example bulky screen updates with the 
non-threaded vnc server are enougth to cause audible glitches in audio 
playback.

HTH,
   Gerd