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author | rubidium <rubidium@openttd.org> | 2009-10-15 17:41:06 +0000 |
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committer | rubidium <rubidium@openttd.org> | 2009-10-15 17:41:06 +0000 |
commit | f4f4044859b9ae89f70dcffc459b81d769c0a93f (patch) | |
tree | 88f1b2f84ce673f3489d6fec18479fb2714da5c1 /src/os/os2 | |
parent | 7f52cfe72bd6471395aa841c7814d2083c179d9f (diff) | |
download | openttd-f4f4044859b9ae89f70dcffc459b81d769c0a93f.tar.xz |
(svn r17776) -Codechange: [SDL] make "update the video card"-process asynchronious. Profiling with gprof etc. hasn't shown us that DrawSurfaceToScreen takes a significant amount of CPU; only using TIC/TOC it became apparant that it was a heavy CPU-cycle user or that it was waiting for something.
The benefit of making this function asynchronious ranges from 2%-25% (real time) during fast forward on dual core/hyperthreading-enabled CPUs; 8bpp improvements are, in my test cases, significantly smaller than 32bpp improvements.
On single core non-hyperthreading-enabled CPUs the extra locking/scheduling costs up to 1% extra realtime in fast forward. You can use -v sdl:no_threads to disable threading and undo this loss.
During normal non-fast-forwarded games the benefit/costs are negligable except when the gameloop takes more than about 90% of the time of a tick.
Note that allegro's performance does not improve with this system, likely due to their way of getting data to the video card. It is not implemented for the OS X/Windows video backends, unless (ofcourse) SDL is used there.
Funny is that the performance of the 32bpp(-anim) blitter is, at least in some test cases, significantly faster (more than 10%) than the 8bpp(-optimized) blitter when looking at real time in fast forward on a dual core CPU; it was slower.
The idea comes from a paper/report by Idar Borlaug and Knut Imar Hagen.
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