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  1. Qt
  2. QTBUG-29264

Rendering stalls in glyph cache

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    • Icon: Bug Bug
    • Resolution: Done
    • Icon: P3: Somewhat important P3: Somewhat important
    • 5.5.1
    • 5.0.0
    • Quick: SceneGraph
    • None

      I am observing non-smooth rendering with an AMD Z430 GPU. The long frame times appear to occur due to QSGDefaultDistanceFieldGlyphCache::storeGlyphs() (in particular the call to resizeTexture() appears to be slow).

      Changing QSGDefaultDistanceFieldGlyphCache::useWorkaroundBrokenFBOReadback() to return true greatly improves the situation. However, there are still significant missed frames.

      Adding a QElapsedTimer to storeGlyphs, and flicking a list with text, the following times are initially reported (in ms):
      178, 46, 72, 66, 69
      with the workaround enabled, the times are (in ms):
      21, 22, 30, 22, 21

        For Gerrit Dashboard: QTBUG-29264
        # Subject Branch Project Status CR V

            ylopes Yoann Lopes
            mbrasser Michael Brasser
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              Created:
              Updated:
              Resolved:

                There are no open Gerrit changes