From mboxrd@z Thu Jan  1 00:00:00 1970
From: Paul Brook <paul@codesourcery.com>
Subject: Re: [Qemu-devel] High CPU use of -usbdevice tablet (was Re: KVM usability)
Date: Sun, 4 Apr 2010 22:03:05 +0100
Message-ID: <201004042203.06119.paul@codesourcery.com>
References: <4B87A6BF.3090301@redhat.com> <201004041525.18211.paul@codesourcery.com> <4BB8C51A.6070908@redhat.com>
Mime-Version: 1.0
Content-Type: Text/Plain;
  charset="utf-8"
Content-Transfer-Encoding: 7bit
Cc: Avi Kivity <avi@redhat.com>, Chris Webb <chris@arachsys.com>,
	kvm@vger.kernel.org,
	Jernej =?utf-8?q?Simon=C4=8Di=C4=8D?=
	<jernej's-kvm@eternallybored.org>
To: qemu-devel@nongnu.org
Return-path: <kvm-owner@vger.kernel.org>
Received: from mail.codesourcery.com ([38.113.113.100]:53258 "EHLO
	mail.codesourcery.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1751115Ab0DDVDK (ORCPT <rfc822;kvm@vger.kernel.org>);
	Sun, 4 Apr 2010 17:03:10 -0400
In-Reply-To: <4BB8C51A.6070908@redhat.com>
Sender: kvm-owner@vger.kernel.org
List-ID: <kvm.vger.kernel.org>

> > The USB HID devices implement the SET_IDLE command, so the polling
> > interval will have no real effect on performance.
> 
> On a Linux guest (F12), I see 125 USB interrupts per second with no
> mouse movement, so something is broken (on the guest or host).

Turns out to be a a bug in the UHCI emulation. It should only raise an 
interrupt if the transfer actually completes (i.e. the active bit is set to 
zero). Fixed by 5bd2c0d7.

I was testing with an OHCI controller, which does not have this bug.

Paul