This branch here: http://cgit.freedesktop.org/~sandmann/xf86-video-qxl/log/?h=trackimages will produce various types of information in the X log file when the option "EnableImageStats" is given in xorg.conf. Specifically, it will track whenever an operation triggers a fallback and record the number of (uncompressed) bytes in the resulting image upload along with a reason that the fallback happened. This repository: http://cgit.freedesktop.org/~sandmann/imganalysis/tree/ contains a Python script that will read the resulting X log files and do some rudimentary analysis on it. There is also a set of log files generated as follows: cnn.log: - Log in - Open Firefox - Go to www.cnn.com pinterest.log: - Log in - Open Firefox - Go to pinterest.com - Scroll down for a good while (the site has inifinte scrolling) oofice.log: - Log in - Open OpenOffice writer - Open this document: http://www.freedesktop.org/~sandmann/tutorialOOoBase.odt - Scroll to the end Each type of log file exists with image caching turned on and off. Caching of *fallback* images was turned on in all cases. The results are available in the attached Gnumeric spreadsheet. The main interesting number is 'Estimated saving from Render excluding nomask', which is 73% with image caching on and 74% with image caching off. This number corresponds to uncompressed image bytes in Render requests that cannot be implemented with existing SPICE protocol commands. The "including nomask" number includes requests that could potentially be implemented with the existing AlphaBlend command. The conclusion is that adding Render acceleration will save around 88% bandwidth, but that around 17% of those could *possibly* be saved without changing the protocol. Some caveats: - With Render acceleration, some bandwidth will still be used for the commands themselves. I don't know how much this will be precisely. - The numbers are before compression. It's conceivably that the types of images generated by Render requests are more or less compressable than those of other types of requests Soren
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