From runge@karlrunge.com Wed Jan 10 19:59:57 2007 Date: Wed, 10 Jan 2007 13:58:50 EST From: Karl J. Runge To: Subject: Re: RFB Caching technique Hi, On Tue, 31 Jan 2006, Vamsi Krishna wrote: > > We, at Novell, have started working on VNC and we want to contribute > to the performance improvements in VNC. We have come up with a > caching idea that we think is not yet present in tight vnc > implementation. > > The draft version of our proposal is available > > http://forge.novell.com/modules/xfcontent/private.php?reference_id=2729&content=/library/RFB%20Caching/rfbcaching.pdf I'm not sure if anyone is interested, but I have implemented an amusing hack that does client-side caching for x11vnc: http://www.karlrunge.com/x11vnc/#faq-client-caching it is in the 0.8.4 development tarball. It is *really* inelegant, it simply creates a huge framebuffer where the top portion is the actual screen; the rest is used for caching pixel data (window backingstores and save-unders) that are swapped in and out via CopyRect. This is nice because it works with all existing VNC viewers, but with the cosmetic defect that you can scroll down and see the pixel cache (which really aids debugging :-) To tidy that up a libvncserver developer and I are thinking that a nice pseudo-encoding might be "rfbFBCrop" or something, that tells the viewer which rectangular region of the full FB it should display to the user. Besides window caching, this could enable double-buffering, offscreen rendering, etc. Well, my hack has very fast response, but it sucks up a huge amount of RAM (roughly 10X on both sides for nice response; this can be dialed down with the -ncache option but then fewer windows are kept "hot"), and so I am sure many will disapprove! However we tend to have a lot of RAM on both sides these days, I personally don't might using some for faster response while working remotely. My tests show the speed/response is approaching that of NX for many activities. x11vnc+Xvfb with this caching turned seems much faster to me than Xvnc (except for a few activities such as scrolling which are always difficult for poor little x11vnc). Anyway, it has only become barely usable in the past week and still has quite a few bugs. If anyone is interested in helping me by testing it in their environment I certainly would appreciate that. Thanks, Karl ------------------------------------------------------------------------- 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 _______________________________________________ VNC-Tight-devel mailing list VNC-Tight-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/vnc-tight-devel