SL-18190 Potential fix for sapping CPU when "sleeping"

2 files changed, 37 insertions, 0 deletions

diff --git a/indra/llcommon/lltimer.cpp b/indra/llcommon/lltimer.cpp
index 39dfee3755..8739eeef00 100644
--- a/indra/llcommon/lltimer.cpp
+++ b/indra/llcommon/lltimer.cpp
@@ -65,6 +65,9 @@ LLTimer* LLTimer::sTimer = NULL;
 //---------------------------------------------------------------------------
 
 #if LL_WINDOWS
+
+
+#if 0
 void ms_sleep(U32 ms)
 {
     LL_PROFILE_ZONE_SCOPED;
@@ -83,6 +86,31 @@ U32 micro_sleep(U64 us, U32 max_yields)
 	ms_sleep((U32)(us / 1000));
     return 0;
 }
+
+#else
+
+U32 micro_sleep(U64 us, U32 max_yields)
+{
+    LL_PROFILE_ZONE_SCOPED
+    LARGE_INTEGER ft;
+    ft.QuadPart = -static_cast<S64>(us * 10);  // '-' using relative time
+
+    HANDLE timer = CreateWaitableTimer(NULL, TRUE, NULL);
+    SetWaitableTimer(timer, &ft, 0, NULL, NULL, 0);
+    WaitForSingleObject(timer, INFINITE);
+    CloseHandle(timer);
+
+    return 0;
+}
+
+void ms_sleep(U32 ms)
+{
+    LL_PROFILE_ZONE_SCOPED
+    micro_sleep(ms * 1000, 0);
+}
+
+#endif
+
 #elif LL_LINUX || LL_DARWIN
 static void _sleep_loop(struct timespec& thiswait)
 {
diff --git a/indra/llwindow/llwindowwin32.cpp b/indra/llwindow/llwindowwin32.cpp
index aadf895271..6beb874e8c 100644
--- a/indra/llwindow/llwindowwin32.cpp
+++ b/indra/llwindow/llwindowwin32.cpp
@@ -66,6 +66,7 @@
 
 #include <d3d9.h>
 #include <dxgi1_4.h>
+#include <timeapi.h>
 
 // Require DirectInput version 8
 #define DIRECTINPUT_VERSION 0x0800
@@ -4827,6 +4828,14 @@ void LLWindowWin32::LLWindowWin32Thread::run()
 
     initDX();
 
+    //as good a place as any to up the MM timer resolution (see ms_sleep)
+    //attempt to set timer resolution to 1ms
+    TIMECAPS tc;
+    if (timeGetDevCaps(&tc, sizeof(TIMECAPS)) == TIMERR_NOERROR)
+    {
+        timeBeginPeriod(llclamp((U32) 1, tc.wPeriodMin, tc.wPeriodMax));
+    }
+
     while (! getQueue().done())
     {
         LL_PROFILE_ZONE_SCOPED_CATEGORY_WIN32;