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Re: [Qemu-devel] [PATCH 6/6] usb-tablet: Allow connecting to ehci


From: Erik Rull
Subject: Re: [Qemu-devel] [PATCH 6/6] usb-tablet: Allow connecting to ehci
Date: Wed, 26 Dec 2012 13:07:50 +0100
User-agent: Mozilla/5.0 (Windows NT 5.1; rv:17.0) Gecko/20100101 Firefox/17.0 SeaMonkey/2.14.1

Hi Gerd, hi Hans,

is my assumption correct that if I check out and compile this version from GIT master that the usb-tablet device is automatically routed to ehci without changing anything else in the qemu call arguments? (And the performance enhancement takes place automatically)
If not - what has to be changed to get it working?

Best regards,

Erik



Gerd Hoffmann wrote:
From: Hans de Goede <address@hidden>

Our ehci code has is capable of significantly lowering the wakeup rate
for the hcd emulation while the device is idle. It is possible to add
similar code ot the uhci emulation, but that simply is not there atm,
and there is no reason why a (virtual) usb-tablet can not be a USB-2 device.

Making usb-hid devices connect to the emulated ehci controller instead
of the emulated uhci controller on vms which have both lowers the cpuload
for a fully idle vm from 20% to 2-3% (on my laptop).

An alternative implementation to using a property to select the tablet
type, would be simply making it a new device type, ie usb-tablet2, but the
downside of that is that this will require libvirt changes to be available
through libvirt at all, and then management tools changes to become the
default for new vms, where as using a property will automatically get
any pc-1.3 type vms the lower cpuload.

[ kraxel: adapt compat property for post-1.3 merge ]

Signed-off-by: Hans de Goede <address@hidden>
Signed-off-by: Gerd Hoffmann <address@hidden>

tablet compat fixup

Signed-off-by: Gerd Hoffmann <address@hidden>




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