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From: | Hans de Goede |
Subject: | Re: [Qemu-devel] [PATCH 18/18] usb: add ehci adapter |
Date: | Tue, 17 May 2011 19:33:05 +0200 |
User-agent: | Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.17) Gecko/20110428 Fedora/3.1.10-1.fc15 Lightning/1.0b2 Thunderbird/3.1.10 |
Hi, On 05/17/2011 05:02 PM, Gerd Hoffmann wrote:
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.
Agreed, I had a hack in my local tree (which I dropped when preparing things for Gerd to pull) which lowered the wakeup rate for UHCI to 200 and then process 5 frames at a time, this worked fine, including redirection of real usb 1 devices, including usb 1 webcam and audio devices. I would actually like to discuss making the wakeup rate for the UHCI controller lower, maybe together with some mechanism for (emulated) input devices to force a wake-up sooner, so as to not add 4 ms of input latency. Regards, Hans
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