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</o:shapelayout></xml><![endif]--></head><body lang=ZH-CN link=blue vlink=purple style='text-justify-trim:punctuation'><div class=WordSection1><p class=MsoNormal><span lang=EN-US>Hi,<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US>I’m considering to implement a delay flushing mechanism to reduce the huge overhead due to<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US>many tiny operations. Currently, I found two typical scenario:<o:p></o:p></span></p><p class=MsoListParagraph style='margin-left:18.0pt;text-indent:-18.0pt;mso-list:l0 level1 lfo1'><![if !supportLists]><span lang=EN-US><span style='mso-list:Ignore'>1.<span style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><span lang=EN-US>Tiny rects filling. The example is firefox-particles. It renders to many small rects with a solid color,<o:p></o:p></span></p><p class=MsoListParagraph style='margin-left:18.0pt;text-indent:0cm'><span lang=EN-US>But each time it just render one rect without using the composite_rects.<o:p></o:p></span></p><p class=MsoListParagraph style='margin-left:18.0pt;text-indent:-18.0pt;mso-list:l0 level1 lfo1'><![if !supportLists]><span lang=EN-US><span style='mso-list:Ignore'>2.<span style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><span lang=EN-US>Less than 4 glyphs a time and repeat many times. The example is gnome-terminal-vim.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US>And there are another example is core library, which will fill one pixel at one request.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US>For all of the above operations, if we call glDrawArray/glDrawElements each time, then the overhead<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US>will be extremely high and the performance is unacceptable.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US>To solve those cases, I’m thinking about delay rendering or batch flushing cross different X requests.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US>We will not always trigger the glDrawArray/glDrawElements at each time. Take glamor_composite as<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US>an example, we will accumulate the vertex buffer if the compositing operations only has a solid source<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US>color. And only when that target pixmap is referenced somewhere, we will flush the all the accumulated<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US>vertex buffers. We may need to change the shader slightly to let the same shader can handle different<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US>solid color, may need to add a color attribute instead of use a uniform value.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US>For the glyphs rendering. If the glyph’s source picture is a solid color, then we can also accumulate the<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US>Glyphs rendering.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US>This mechanism is widely applied in other 2D libraries such as cairo. But I haven’t found any DDX use it.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US>I haven’t found any critical obstacle to use it in DDX driver. Want to get some comments from the list.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US>Thanks.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p></div></body></html>