From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:41263) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aIjeq-0003ct-Vd for qemu-devel@nongnu.org; Mon, 11 Jan 2016 16:05:49 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1aIjem-0004uY-Ll for qemu-devel@nongnu.org; Mon, 11 Jan 2016 16:05:44 -0500 Received: from vps01.wiesinger.com ([46.36.37.179]:59032) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aIjem-0004XS-FD for qemu-devel@nongnu.org; Mon, 11 Jan 2016 16:05:40 -0500 References: <5666A553.8070009@wiesinger.com> <56913969.3000305@wiesinger.com> <56936630.2030907@redhat.com> From: Gerhard Wiesinger Message-ID: <569418DA.9070907@wiesinger.com> Date: Mon, 11 Jan 2016 22:04:26 +0100 MIME-Version: 1.0 In-Reply-To: <56936630.2030907@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] QEMU/KVM performance gets worser - high load - high interrupts - high context switches List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini , qemu-devel@nongnu.org On 11.01.2016 09:22, Paolo Bonzini wrote: > > On 09/01/2016 17:46, Gerhard Wiesinger wrote: >> # Positive consequences via munin monitoring: >> # Reduced fork rate: 40 =3D> 13 >> # process states: running 15 =3D> <1 >> # C=C3=9CU temperature: (core dependant) 65-70=C2=B0C =3D> 56-64=C2=B0= C >> # CPU usage: system: 47% =3D> 15%, user: 76% =3D> 50% >> # Context Switches: 20k =3D> 7.5k >> # Interrupts: 16k =3D> 9k >> # Load average: 2.8 =3D> 1 >> >> =3D> back at the level before one year!!!!!!! >> >> Any idea why the serial device/PCI controller and the USB mouse tablet >> consume so much CPU on latest kernel and/or qemu? > For USB, it's possible that you're not using the USB autosuspend > feature? (As explained in Gerd's blog post, for Microsoft OSes you may > need to fiddle with the registry). > > For virtio-serial, I have no idea. Linux VMs: All VMs are Linux VM on this KVM host, so as per blog post=20 udev rules should apply well for USB autosuspend. Most of the effect=20 came from the virtio-serial and not from USB tablet. For another KVM host with a Windows 7 VM: I tried to find apply the blog post: But there is no option "Allow the=20 computer to turn off the device to save power" Nevertheless CPU usage could be reduced by removing the USB tablet from=20 the Win7 VM. Ciao, Gerhard