Matthew Garrett on the race to idle

Matthew Garrett on the race to idle

Posted May 13, 2008 14:46 UTC (Tue) by farnz (subscriber, #17727)
In reply to: Matthew Garrett on the race to idle by daenzer
Parent article: Matthew Garrett on the race to idle

We do use X11 for rendering, but it's definitely the move from a low C-state that kills us. We can easily measure the latency of the rendering operation; in the worst case we've seen thus far (not on an Intel platform), we see around 0.03 milliseconds between the wait for VBlank syscall returning, and us being about to enter the wait again. Note that we sync the X stream at this point, so we don't re-enter the wait until the server has finished drawing.

Note that we don't draw by blitting a new frame from scratch; we delta the existing on-screen frame instead, which minimises the work involved.

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