OpenGL - Fullscreen Exclusive under-utilizes the GPU

Franpa · (This post was last modified: 10-19-2021, 04:01 AM by Franpa.)

For some strange reason GPU usage (and FPS) decreases when engaging Fullscreen Exclusive mode compared to Windowed mode. Observed in Final Fantasy: Crystal Chronicles: My Life as a King with high resolution scaling (6x and 8x). Stand near & looking at the big blue crystal and toggling display mode with Alt-Enter should be sufficient enough to observe the variance.

https://www.youtube.com/watch?v=03GyWry33ws

Edit: It might be that GPU-Z and Task Manager both detect GPU usage the same way and are both wrong for the same reason. MSI Afterburner seems to better detect GPU usage.

**KHg8m3r** · 09-30-2021, 11:00 PM #2

Do you have a profile setup for Dolphin in the Nvidia Control Panel? You should set the Power Management Mode to "Prefer maximum performance" (and don't change anything else for Dolphin)

Franpa · 10-01-2021, 07:11 AM #3

That's already been configured globally, I don't have Dolphin specific app profile.

**JMC47** · 10-01-2021, 07:43 AM #4

It's probably vsync/vblank differences, everything is normal here.

Franpa · (This post was last modified: 10-01-2021, 08:47 PM by Franpa.)

I made a video showcasing it: https://www.youtube.com/watch?v=03GyWry33ws
I used Special_K in this recording to show GPU Usage below Dolphin's FPS indicator. I don't normally use Special_K with Dolphin. Original observation of GPU utilization was via Task Manager.

Edit: The issue happens regardless of the load on the GPU, the phenomena is however considerably more severe and more easily demonstrated in high GPU usage scenarios.
Edit 2: Configuration of Dolphin

Code:

[General]

ShowLag = False

ShowFrameCount = False

ISOPaths = 2

RecursiveISOPaths = True

NANDRootPath =

DumpPath =

WirelessMac =

WiiSDCardPath =

ISOPath0 =

ISOPath1 =

LastFilename =

UseGameCovers = True

UseDiscordPresence = False

GDBPort = -1

[Interface]

ConfirmStop = True

UsePanicHandlers = True

OnScreenDisplayMessages = True

HideCursor = False

MainWindowPosX = 173

MainWindowPosY = 316

MainWindowWidth = 776

MainWindowHeight = 600

LanguageCode =

ShowToolbar = True

ShowStatusbar = True

ShowLogWindow = False

ShowLogConfigWindow = False

ExtendedFPSInfo = False

ShowActiveTitle = True

UseBuiltinTitleDatabase = True

ShowDevelopmentWarning = True

ThemeName = Clean

PauseOnFocusLost = False

DisableTooltips = False

AutoHideCursor = False

Language = 0

ThemeName40 = Clean

DebugModeEnabled = False

LockCursor = False

[Display]

FullscreenResolution = 1920x1080

Fullscreen = False

RenderToMain = False

RenderWindowXPos = 929

RenderWindowYPos = 153

RenderWindowWidth = 914

RenderWindowHeight = 727

RenderWindowAutoSize = False

KeepWindowOnTop = False

DisableScreenSaver = True

ForceNTSCJ = False

ProgressiveScan = False

PAL60 = True

FullscreenDisplayRes = Auto

[GameList]

ListDrives = False

ListWad = True

ListElfDol = True

ListWii = True

ListGC = True

ListJap = True

ListPal = True

ListUsa = True

ListAustralia = True

ListFrance = True

ListGermany = True

ListItaly = True

ListKorea = True

ListNetherlands = True

ListRussia = True

ListSpain = True

ListTaiwan = True

ListWorld = True

ListUnknown = True

ListSort = 3

ListSortSecondary = 0

ColumnPlatform = True

ColumnBanner = True

ColumnDescription = False

ColumnTitle = True

ColumnNotes = True

ColumnFileName = False

ColumnID = False

ColumnRegion = True

ColumnSize = True

ColumnState = True

ColorCompressed = True

ColumnTags = False

ColumnFilePath = False

ColumnFileFormat = False

ColumnBlockSize = False

ColumnCompression = False

[Core]

SkipIPL = True

TimingVariance = 40

CPUCore = 1

Fastmem = True

CPUThread = True

DSPHLE = True

SyncOnSkipIdle = True

SyncGPU = True

SyncGpuMaxDistance = 200000

SyncGpuMinDistance = -200000

SyncGpuOverclock = 1.00000000

FPRF = False

AccurateNaNs = False

DefaultISO =

EnableCheats = True

SelectedLanguage = 0

OverrideGCLang = False

DPL2Decoder = False

AudioLatency = 2

AudioStretch = False

AudioStretchMaxLatency = 10

MemcardAPath =

MemcardBPath =

AgpCartAPath =

AgpCartBPath =

SlotA = 1

SlotB = 255

SerialPort1 = 255

BBA_MAC =

SIDevice0 = 6

AdapterRumble0 = True

SimulateKonga0 = False

SIDevice1 = 12

AdapterRumble1 = True

SimulateKonga1 = False

SIDevice2 = 12

AdapterRumble2 = True

SimulateKonga2 = False

SIDevice3 = 12

AdapterRumble3 = True

SimulateKonga3 = False

WiiSDCard = True

WiiKeyboard = True

WiimoteContinuousScanning = False

WiimoteEnableSpeaker = False

RunCompareServer = False

RunCompareClient = False

EmulationSpeed = 1.00000000

FrameSkip = 0x00000000

Overclock = 4.00000000

OverclockEnable = True

GFXBackend = OGL

GPUDeterminismMode = auto

PerfMapDir =

EnableCustomRTC = False

CustomRTCValue = 0x386d4380

EnableSignatureChecks = True

HLE_BS2 = False

SkipIdle = True

DVDRoot =

Apploader =

Latency = 2

AutoDiscChange = True

DPL2Quality = 2

OverrideRegionSettings = False

MMU = False

WiimoteControllerInterface = False

BBA_XLINK_IP = 127.0.0.1

BBA_XLINK_CHAT_OSD = True

FallbackRegion = 1

[Movie]

PauseMovie = False

Author =

DumpFrames = False

DumpFramesSilent = False

ShowInputDisplay = False

ShowRTC = False

[DSP]

EnableJIT = False

DumpAudio = False

DumpAudioSilent = False

DumpUCode = False

Backend = WASAPI (Exclusive Mode)

Volume = 10

CaptureLog = False

WASAPIDevice = default

[Input]

BackgroundInput = True

[FifoPlayer]

LoopReplay = True

[Analytics]

ID =

Enabled = True

PermissionAsked = True

[Network]

SSLDumpRead = False

SSLDumpWrite = False

SSLVerifyCertificates = True

SSLDumpRootCA = False

SSLDumpPeerCert = False

[BluetoothPassthrough]

Enabled = False

VID = -1

PID = -1

LinkKeys =

[USBPassthrough]

Devices =

[AutoUpdate]

UpdateTrack = beta

HashOverride =

[NetPlay]

TraversalChoice = direct

[Debug]

JitOff = False

JitLoadStoreOff = False

JitLoadStoreFloatingOff = False

JitLoadStorePairedOff = False

JitFloatingPointOff = False

JitIntegerOff = False

JitPairedOff = False

JitSystemRegistersOff = False

JitBranchOff = False

JitRegisterCacheOff = False

[GBA]

BIOS =

Rom1 =

Rom2 =

Rom3 =

Rom4 =

SavesInRomPath = False

SavesPath =

Threads = True

Franpa · (This post was last modified: 10-06-2021, 12:25 AM by Franpa.)

So, any other ideas on why Fullscreen Exclusive causes severe FPS drops and reduction of GPU utilization in demanding scenarios? It happens in multiple games, Metroid Prime 2 for example will drop to 55FPS in some niche situations in windowed mode and 40FPS in Fullscreen Exclusive in the same location.

And before you say to play in windowed/borderless fullscreen, I get anomalous frame pacing issues in that mode (visual stutter unrelated to FPS).

Is it really just a difference in how Vsync handles FPS below the refresh rate for OpenGL? Reducing by a flat 3rd as though Triple Buffering was in effect while Windowed mode doesn't do that?

**JosJuice** · 10-06-2021, 12:42 AM #7

(10-06-2021, 12:14 AM)Franpa Wrote: Is it really just a difference in how Vsync handles FPS below the refresh rate for OpenGL? Reducing by a flat 3rd as though Triple Buffering was in effect while Windowed mode doesn't do that?

If you have a 120 Hz monitor, then yes (120 divided by 3). But if you have a 60 Hz monitor, you should be getting either a flat 60 Hz or a flat 30 Hz with vsync.