From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1G4xEW-0000kh-1p for qemu-devel@nongnu.org; Mon, 24 Jul 2006 06:00:16 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1G4xES-0000hP-Fb for qemu-devel@nongnu.org; Mon, 24 Jul 2006 06:00:13 -0400 Received: from [199.232.76.173] (helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1G4xES-0000hC-5E for qemu-devel@nongnu.org; Mon, 24 Jul 2006 06:00:12 -0400 Received: from [203.190.192.17] (helo=wasp.net.au) by monty-python.gnu.org with esmtp (Exim 4.52) id 1G4xFV-0006Cb-KY for qemu-devel@nongnu.org; Mon, 24 Jul 2006 06:01:18 -0400 Message-ID: <44C49A23.6010103@wasp.net.au> Date: Mon, 24 Jul 2006 14:00:03 +0400 From: Brad Campbell MIME-Version: 1.0 Subject: Re: [Qemu-devel] Performance issues with -usb References: <44C48DAD.9010301@wasp.net.au> <1153733038.4270.8.camel@vaio> In-Reply-To: <1153733038.4270.8.camel@vaio> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Reply-To: qemu-devel@nongnu.org List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Lonnie Mendez wrote: > Perhaps tweaking the value of ep_bInterval for the tablet's status > change endpoint would help? The endpoint descriptor for the tablet > currently has this at 3 milliseconds. The hid mouse reports a 10 > millisecond polling interval. Indeed. I'm not quite sure how or why I did that in the 1st place as the tablet started life as a copy of the mouse in any case. I've had good drag through the specs and all the data sheets for mouse chips I could find out there and most of them seem to recommend a value no faster than 8ms. This drops the cpu utilisation of a Windows guest while idle about 75% when using -usbdevice tablet I've not noticed any change in usability or mouse responsiveness. (I played with values up to 0xFF but after about 0x20 there seemed to be immeasurable/no difference) Index: hw/usb-hid.c =================================================================== RCS file: /cvsroot/qemu/qemu/hw/usb-hid.c,v retrieving revision 1.5 diff -u -r1.5 usb-hid.c --- hw/usb-hid.c 19 Jul 2006 18:06:15 -0000 1.5 +++ hw/usb-hid.c 24 Jul 2006 09:55:22 -0000 @@ -169,7 +169,7 @@ 0x81, /* u8 ep_bEndpointAddress; IN Endpoint 1 */ 0x03, /* u8 ep_bmAttributes; Interrupt */ 0x08, 0x00, /* u16 ep_wMaxPacketSize; */ - 0x03, /* u8 ep_bInterval; (255ms -- usb 2.0 spec) */ + 0x20, /* u8 ep_bInterval; (255ms -- usb 2.0 spec) */ Brad -- "Human beings, who are almost unique in having the ability to learn from the experience of others, are also remarkable for their apparent disinclination to do so." -- Douglas Adams