On Fri, Jan 27, 2017 at 06:08:20PM +0000, Daniel P. Berrange wrote: > On Fri, Jan 27, 2017 at 09:35:38AM +0000, Daniel P. Berrange wrote: > > On Tue, Jan 24, 2017 at 05:02:25PM -0500, Brian Rak wrote: > > > We've been considering switching over to using qemu's built in websockets > > > support (to avoid the overhead of needing websockify running). We've been > > > seeing very poor performance after the switch (it takes the console 4-5 > > > seconds to update after pressing a key). So far, I haven't been able to > > > find any indication of why this is happening. The exact same > > > configuration > > > works perfectly when running with websockify, but laggy when hitting qemu > > > directly. > > > > > > I've tried a few things (disabling encryption, bypassing our usual nginx > > > proxy, even connecting via a ssh tunnel), and haven't made any sort of > > > progress here. Has anyone else seen this? Any suggestions as to where I > > > should start looking? > > > > Can you clarify the exact setup you have ? As mentioned on IRC, I don't > > see any degradation in performance betweeen builtin websockets vs a > > websockets proxy - if anything the builtin websockets is marginally less > > laggy. I was connecting over TCP localhost, however, so would not see > > any effects of network latency. My test was QEMU git master, with noVNC > > git master. > > It turns out that to see the problem you have a wait a while - the > connection is initially fine, but gets worse over time. Using a TCP > connection seems to make it get worse more quickly. > > After a painful debugging session I've discovered the problem is that > QEMU is reading data off the socket, decoding a websockets packet and > then processing it. The problem is if the read off the socket gets > multiple websockets packets at once, it only decodes the first packet. > The remaining packets aren't decoded until more data arrives on the > socket. This gets progressively worse & worse. I'll send a patch for > this next week...
I've just sent a patch & would appreciate your testing to confirm that it fixes the problem for you too. Regards, Daniel -- |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://entangle-photo.org -o- http://search.cpan.org/~danberr/ :|
