Commit ffa9c397 authored by 157.24.24.192's avatar 157.24.24.192
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explain xinerama speed penalty effect

parent 0509d2ee
......@@ -16,7 +16,9 @@ The above limitation with SCREENs and applications is very inconvenient, when on
Along with the Xinerama feature came the Xinerama extension, which allows applications to query the physical monitor configuration. For instance, a Xinerama-aware window manager can maximize a window to fit one monitor instead of covering all monitors. For applications (window managers), there is the Xinerama library, {{{libXinerama}}} for using the Xinerama extension.
The drawbacks of Xinerama are noticeable. When any accelerated 2D rendering operation (core, Render, or Xv) is performed, it must be executed on every card. Each card maintains its own copy of all the rendering state, which means that all pixmaps (images) must be copied to every card, too. Because the X server is single-threaded, rendering takes more time by the number of cards. Furthermore, Xinerama does not handle GLX, so 3D acceleration is disabled.
The drawbacks of Xinerama are noticeable. When any accelerated 2D rendering operation (core, Render, or Xv) is performed, it must be executed on every card. Each card maintains its own copy of all the rendering state, which means that all pixmaps (images) must be copied to every card, too. Because the X server is single-threaded, rendering takes more time by the number of cards.
The rendering speed in a Xinerama configuration is practically always worse than what the ''slowest'' card is able to achieve alone.
Furthermore, Xinerama does not handle GLX, so 3D acceleration is disabled.
One more annoyance is, that the DPI (dots-per-inch) resolution is fixed to the same value over all monitors.
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