If you're running under Aero composition on Vista/W7 (and perhaps W8, haven't tested there), Aero will sometimes decide to dispatch paint events (and as a result, composite) less often in response to measured GPU load and other characteristics. That might be responsible for what you're seeing there. http://graphics.stanford.edu/~mdfisher/GPUView.html might be able to tell you.
-kg On Wed, Aug 8, 2012 at 6:16 PM, Matt Woodrow <mwood...@mozilla.com> wrote: > > >>Are there details on what this actually means? e.g. don't we *have* to >>paint when when we receive a WM_PAINT event, and usually we shouldn't at >>other times? > > To clarify, these patches split painting up into two steps: > > 1) Compute invalid regions, build display lists, layers and repaint the > changed areas of our retained layers. > 2) Composite the retained layers onto the screen. > > Previously both steps were done in response to the WM_PAINT event, now we do > part 1 off the refresh driver, and just part 2 from WM_PAINT > > OMTC will move part 2 onto a separate thread entirely and the only thing we > need to do in response to WM_PAINT will be notify the compositor to draw to > the screen asap. > > >>"Artificially" meaning "the computer has idle CPU and could issue >>WM_PAINT at 60 fps but the OS decides not to?" Do we know why the OS >>behaves in this way? > > I don't have any information on why the OS isn't sending WM_PAINT events as > quickly as we request them. > >>Is this regression in Tp times matched by an improvement in perceived >>performance because we're painting more often? If so, I think this >>tradeoff makes sense (although I'd hope we had metrics which could >>measure this perceived improvement). > > As mentioned before, these extra paints don't actually make it to the screen > without OMTC, so unfortunately not. > > This should definitely be true once OMTC lands for desktop, and already true > for android. > > I just measured the fps of our drawing (not necessarily compositing to the > screen) while running tp5 and these patches increase it significantly (13fps > -> 22fps). > > >>I'm a little wary of just taking a 5-8% Tp hit though! > > Me too! > > --BDS > > _______________________________________________ > dev-platform mailing list > dev-platform@lists.mozilla.org > https://lists.mozilla.org/listinfo/dev-platform -- -kg _______________________________________________ dev-platform mailing list dev-platform@lists.mozilla.org https://lists.mozilla.org/listinfo/dev-platform
