From f4f4044859b9ae89f70dcffc459b81d769c0a93f Mon Sep 17 00:00:00 2001 From: rubidium Date: Thu, 15 Oct 2009 17:41:06 +0000 Subject: (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. --- src/thread/thread_win32.cpp | 15 +++++++++++++++ 1 file changed, 15 insertions(+) (limited to 'src/thread/thread_win32.cpp') diff --git a/src/thread/thread_win32.cpp b/src/thread/thread_win32.cpp index e752de1ae..a3b2d3734 100644 --- a/src/thread/thread_win32.cpp +++ b/src/thread/thread_win32.cpp @@ -107,16 +107,19 @@ private: class ThreadMutex_Win32 : public ThreadMutex { private: CRITICAL_SECTION critical_section; + HANDLE event; public: ThreadMutex_Win32() { InitializeCriticalSection(&this->critical_section); + this->event = CreateEvent(NULL, FALSE, FALSE, NULL); } /* virtual */ ~ThreadMutex_Win32() { DeleteCriticalSection(&this->critical_section); + CloseHandle(this->event); } /* virtual */ void BeginCritical() @@ -128,6 +131,18 @@ public: { LeaveCriticalSection(&this->critical_section); } + + /* virtual */ void WaitForSignal() + { + this->EndCritical(); + WaitForSingleObject(this->event, INFINITE); + this->BeginCritical(); + } + + /* virtual */ void SendSignal() + { + SetEvent(this->event); + } }; /* static */ ThreadMutex *ThreadMutex::New() -- cgit v1.2.3-54-g00ecf