From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:40723) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QMLnE-00039G-45 for qemu-devel@nongnu.org; Tue, 17 May 2011 11:02:41 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1QMLnD-0006G5-4K for qemu-devel@nongnu.org; Tue, 17 May 2011 11:02:40 -0400 Received: from mx1.redhat.com ([209.132.183.28]:37125) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QMLnC-0006G0-SY for qemu-devel@nongnu.org; Tue, 17 May 2011 11:02:39 -0400 Message-ID: <4DD28E0A.2050808@redhat.com> Date: Tue, 17 May 2011 17:02:34 +0200 From: Gerd Hoffmann MIME-Version: 1.0 References: <1305575782-31766-1-git-send-email-kraxel@redhat.com> <1305575782-31766-19-git-send-email-kraxel@redhat.com> <4DD1E1DD.3060605@cisco.com> <4DD221AB.7070009@redhat.com> <4DD26D45.3070309@cisco.com> <4DD27D9D.1050109@cisco.com> In-Reply-To: <4DD27D9D.1050109@cisco.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 18/18] usb: add ehci adapter List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: David Ahern Cc: qemu-devel@nongnu.org Hi, > (And by the way, where are the focused patches for each, especially the > last one - nuking the 8kHz code? It's squashed in, like everything else. > We know that it worked on linux and > that printers, scanners and storage devices worked ok (mostly). 8 kHz is insane. I looked closely while trying to make 8 kHz a runtime option instead of a compile time option, then decided to drop it altogether as it is totally pointless. qemu simply can't handle that wakeup rate. It maxed out at ~3 kHz wakeups in my tests. And it burns tons of CPU time. I also don't see what it would buy us. We can wakeup with 1 kHz rate (maybe even lower), then emulate 8 (or more) microframes each time. Throughput issues (guess this is the reason to try 8kHz wakeups) need to be addressed by modeling data pipes in the usb system instead of playing ping-pong between EHCI and USB device emulation for each single usb packet, at 8 kHz. I see the ehci merge just as very first step. USB 2.0 (and 3.0) support in qemu still has a loooooooong way to go. cheers, Gerd