Note the changed subject line. I just did a few tests with linux guest (amd64 2.6.35 kernel). And it shows the same behavour as win7 (unlike winXP), namely, high host CPU load when guest is idle. When I run this guest (which network-boots and only runs udevd and a busybox shell after loading all needed drivers) without -usbdevice, the host shows <1% CPU usage when this guest is idle. But once I add -usbdevice -- be it tablet or mouse - guest starts eating 16..19% host cpu when idling. Note that there's no other services running - no dbus, X, inetd etc, just udevd, busybox's init and sh. So now we've quite well-supported debuggable guest. Looking at /proc/interrupts in guest discovers nothing interesting. Even the usb irq# is not increasing. But I looked at usb endpoint descriptors in qemu, in particular hw/usb-hid.c. There, all bInterval values - apparently - assumes usb-2.0 specs. But as far as I can see, all devices are usb-1, where bInterval is expressed in different units - in ms. So, for example, bInterval=10 for the table is _not_ 255ms, it is 10ms! For it to be 255, actual value = 255 should be written in bInterval. I tried changing this field directly, but it didn't help. It reduced idle cpu usage for a few percents however. Probably that's because there are also usb root hubs and other similar stuff which needs to be checked too. I'll do it in a moment. Reportedly, this problem (high system load during idle) first shows with win7/win2008. My _guess_ would be that starting with this version of windows it actually is able to honour this 10ms interval - XP definitely does not, it pools mouse every 130ms. But this is just guesses and speculations... Digging further. Answering to the sdl question: the linux guest experiment shows that sdl has nothing to do with this, since linux does not do any vga updates at all when idles in text mode... Thanks! /mjt -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
