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Optimize idle cpu usage by implementing our own fps limiter

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bloeys
2022-07-22 18:52:35 +04:00
parent 90b0bc0ae9
commit 0d2e747739
1 changed files with 29 additions and 2 deletions
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31
main.go
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@ -33,6 +33,9 @@ import (
type Settings struct {
DefaultColor gglm.Vec4
StringColor gglm.Vec4
MaxFps int
LimitFps bool
}
type Cmd struct {
@ -72,6 +75,8 @@ type program struct {
activeCmd *Cmd
Settings *Settings
frameStartTime time.Time
}
const (
@ -109,7 +114,9 @@ func main() {
panic("Failed to create window. Err: " + err.Error())
}
engine.SetVSync(true)
// We do our own fps limiting because (at least some) drivers vsync by doing a busy loop and spiking
// CPU to 100% doing nothing instead of a sleep
engine.SetVSync(false)
p := &program{
win: win,
@ -129,6 +136,8 @@ func main() {
Settings: &Settings{
DefaultColor: *gglm.NewVec4(1, 1, 1, 1),
StringColor: *gglm.NewVec4(242/255.0, 244/255.0, 10/255.0, 1),
MaxFps: 120,
LimitFps: true,
},
}
@ -197,6 +206,8 @@ func (p *program) Init() {
func (p *program) Update() {
p.frameStartTime = time.Now()
if input.IsQuitClicked() || input.KeyClicked(sdl.K_ESCAPE) {
engine.Quit()
}
@ -705,10 +716,10 @@ func (p *program) DebugRender() {
p.DrawGrid()
}
fps := int(timing.GetAvgFPS())
if len(textToShow) > 0 {
str := textToShow
charCount := len([]rune(str))
fps := int(timing.GetAvgFPS())
if drawManyLines {
const charsPerFrame = 500_000
for i := 0; i < charsPerFrame/charCount; i++ {
@ -720,6 +731,8 @@ func (p *program) DebugRender() {
p.GlyphRend.DrawTextOpenGLAbsString(str, gglm.NewVec3(xOff, float32(p.GlyphRend.Atlas.LineHeight)*5+yOff, 0), &p.Settings.DefaultColor)
p.win.SDLWin.SetTitle(fmt.Sprint("FPS: ", fps, " Draws/f: ", math.Ceil(charsPerFrame/glyphs.DefaultGlyphsPerBatch), " chars/f: ", int(charsPerFrame), " chars/s: ", fps*int(charsPerFrame)))
}
} else {
p.win.SDLWin.SetTitle(fmt.Sprint("FPS: ", fps))
}
}
@ -742,6 +755,20 @@ func (p *program) DrawGrid() {
func (p *program) FrameEnd() {
assert.T(p.cursorCharIndex <= p.cmdBufLen, fmt.Sprintf("Cursor char index is larger than cmdBufLen! You probablly forgot to move/reset the cursor index along with the buffer length somewhere. Cursor=%d, cmdBufLen=%d\n", p.cursorCharIndex, p.cmdBufLen))
if p.Settings.LimitFps {
elapsed := time.Since(p.frameStartTime)
microSecondsPerFrame := int64(1 / float32(p.Settings.MaxFps) * 1000_000)
// Sleep time is reduced by a millisecond to compensate for the (nearly) inevitable over-sleeping that will happen.
timeToSleep := time.Duration((microSecondsPerFrame - elapsed.Microseconds()) * 1000)
timeToSleep -= 1000 * time.Microsecond
if timeToSleep.Milliseconds() > 0 {
time.Sleep(timeToSleep)
}
}
}
func (p *program) DeInit() {