Anthony Liguori wrote: > Avi Kivity wrote: >> There are four issues I can see: >> >> - if there are multiple sources of kvm userspace, there are bound to >> be problems with incompatible kernel API and userspace, especially as >> I have plans for extensive changes to the API. I'll go and implement >> a version check now, so that doesn't become a barrier to anything. A >> submission to qemu-devel should include this check. > > With KQEMU, you have to pair a version of KQEMU with the appropriate > version of QEMU. I don't think there's much of a problem doing > something like this for KVM for the short term until API gets more > stable (provided there's a version check so the error is useful to the > user). >
The version check is now in. > >>> diff -r 2eac80033ea0 hw/usb-hid.c >>> --- a/hw/usb-hid.c Tue Dec 19 09:31:34 2006 +0000 >>> +++ b/hw/usb-hid.c Wed Dec 20 23:01:25 2006 -0600 >>> @@ -169,7 +169,9 @@ static const uint8_t qemu_tablet_config_ >>> 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) */ >>> + /* Temporarily increase usb polling interval to prevent cpu >>> + * saturation (3 ms is way too often for kvm) */ >>> + 0x33, /* u8 ep_bInterval; (255ms -- usb 2.0 spec) */ >>> >> >> This might be a good change for qemu, but on the other hand this is a >> kvm deficiency that is forced on non-kvm users. > > Brad Campbell (who wrote the original HID description) has recently > posted a patch that changes the interval to 0x20. 0x03 was causing a > performance problems with Windows guests (there's a pretty recent > thread on qemu-devel about it). > > How did you arrive at 0x33 btw? IIRC, Brad stopped at 0x20 as he saw > no performance improvement beyond it. If KVM needs at least 0x33 then > provided there is no negative impact to QEMU I don't really see a > problem with it. It's just a random number, the first I tried. 0x20 would probably work just as well (30 interrupts/sec) -- error compiling committee.c: too many arguments to function ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys - and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel
