StutterShark

StutterShark runtime, resolver, and test binary notes are consolidated here from the 2026-05-19 snapshot.

2026-05-19 application notes

StutterShark.exe

What this program actually does

StutterShark.exe is the Platform Seat Service daemon on a GeForce NOW gameseat. It runs as Windows service StutterSharkService, hosts four in-process plugins, and monitors realtime stutter and deadzone for the active game session. It initializes NVML/NVAPI, subscribes to SSLM session lifecycle via MessageBus, fetches CSR config from GSConfigurator, publishes GPU perf counters, and emits telemetry on schema gfn-team.open.stuttershark:14.

Log banner in this snapshot: Platform Seat Service v0.13.10.

---

Architecture / control flow (recovered symbols)

main / ServiceHost (CServiceBase@systemservicebase@nv)
  └─ PlatformSeatService::OnStart
        ├─ PlatformSeatService::InitializeTas / InitializeCsr
        ├─ PlatformSeatService::MbListenThread  → MessageBus peer PlatformSeatService:StutterShark
        ├─ GSConfigClient → PssConfigData, SeatConfig
        ├─ SslmSubscriptionTracker / SslmObserver
        ├─ CPUID::Manager (NvpBridge channel)
        └─ PlatformSeatService::LoadPlugins
              ├─ StutterSharkPlugin      (ETW stutter detection, stack dumps)
              ├─ UmdPerfCounterPlugin    (NVAPI/NVML GPU counters → Kratos)
              ├─ VcpuBoostControllerPlugin (vCPU clock boost via CPUID)
              └─ GpuControllerPlugin     (TGP/GPC capping, frame-time compositor)

Plugin base: BasePlugin state machine (Uninitialized → Initializing → Initialized → Starting → Started → Stopping → Terminated).

Build tree: C:\builds\gfn-foundations\stuttershark\ (ServiceLib.cpp, plugin sources under Plugins\).

PDB: C:\builds\gfn-foundations\stuttershark\out\x64-windows-release\Service\StutterShark.pdb

---

RTTI / telemetry types (deep extract sample)

Class / field type	Role
BasePlugin, CServiceBase@systemservicebase@nv	Service + plugin framework
GSConfigClient@gsprerequisites, Connector@tas@gs@gfn@nv	Config + TAS telemetry
AppSensorMessage_*, AppServiceApi_SopsAppliedEvent	MessageBus session/SOPS events
*@Fields@StutterSharkSchema	Telemetry fields (stutter counts, GPU cap stats, callstack sampling flags)
BaseGpuController, GpuControllerSummarizedDataPoint	GPU controller plugin internals

---

External interfaces

Interface	Role
Windows Service StutterSharkService	Installed via StutterShark.exe --install; auto-start + failure restart (sc failure) per install log
MessageBus	Peers PlatformSeatService:StutterShark, PlatformSeatService:StutterSharkTelemetry; config C:\asgard\services\gsp\MessageBus\x64\messagebus.conf (string)
GSConfigurator	Fetches PssConfigData, SeatConfig (Services=["StutterSharkService"])
SSLM (NGS:SSLM)	Subscribes for session state; waits for session-finished notification before tearing down bus
NVML / NVAPI	GPU enumeration, perf counters, controller policies
ETW / TDH / dbghelp	Stutter trace sessions, callstack capture
NvpBridge kernel driver	Installed via devcon + nvpbridge.inf; CPUID trusted channel
Perf counters	UmdPerfCounterPlugin.man, NvpBridge\nvpbridge.man via lodctr
Logs	logs/StutterShark/PlatformSeatService.log

CLI strings (not service path): --stutter-min-threshold, --per-stutter-detail; description: "Realtime stutter and deadzone monitor and dumping service. CLI mode: Ctrl-C to kill".

---

Plugin lifecycle (strings + logs)

Component	Evidence
serviceLibRunPluginsInPrewarm	CSR Run Plugins in Prewarm true at 18:43:16
StutterShark plugin CSR	Detection Disabled false, Detection Threshold 100 ms
VcpuBoostController CSR	Disabled false, ForceDefaultFreq true
Background callstack sampling	Disabled true
Dynamic GPU Cap	Disabled false, GPU Controller Prewarm Throttle GPU true
Session gate	BlockUntilFirstSessionEvent — waited 326000 ms for SOPS before starting plugins

Session start (18:48:43–44): StutterShark, UmdPerfCounter, GpuController reach Started; VcpuBoostController early-stopped (Clock control feature support query failed).

---

Runtime timeline (from logs/StutterShark/PlatformSeatService.log)

Time (local)	Event
18:43:16.442	Service v0.13.10; MessageBus join PlatformSeatService:StutterShark
18:43:16.476–489	NVML + NVAPI init; 1 GPU on vGPU (00000000:0c:00.0)
18:43:16.512–534	GSConfigurator configs fetched
18:43:16.535	CSR plugin configs applied
18:43:16.585	SSLM subscription cancelled (NGS not yet on bus)
18:43:22.405	SSLM subscribed after NGS:SSLM joined
18:48:41.854	SopsAppliedEvent: 1920×1080@60, cmsId [REDACTED_CMS_ID], instance [REDACTED_POOL]
18:48:44.551	StutterShark Service started; NvpBridge perf counters initialized
18:48:58+	Target process tracking (conhost.exe, seelen-ui.exe); repeated Empty stutter detect event passed in

---

Failure modes (log + strings)

String / log line	Meaning
Plugin is hung, skipping state change	Plugin state transition timeout
Timeout waiting for SSLM session finished notification	SSLM cleanup may be incomplete
Empty stutter detect event passed in	Stutter detector received invalid event (observed repeatedly post-session)
TGP limit setting failed / GPC clock setting failed	GpuController policy apply failed on vGPU seat
Register Fan Cooler callback failed error NVAPI_TIMEOUT	UmdPerfCounter NVAPI callback registration failure
CPUID Interface state control support query failed	CPUID channel teardown error

---

Relationships

Component	Interaction
StutterSharkResolve.exe	Offline stack/symbol resolver for captured traces (bundled, not invoked in this session)
StutterSharkTest.exe	Unit/integration tests for same plugin stack
GSConfiguratorPlugin	Config authority for CSR/PSS
Morph, GfnSdkService	Sibling seat services; all subscribe to SSLM after NGS joins
SmithyController	Observes bus peers PlatformSeatService:StutterShark, StutterSharkTelemetry
services/StutterShark/DLL/	Ships dbghelp_new.dll, msdia140.dll, symsrv.dll, srcsrv.dll for symbol resolution

---

Not verified

• Exact MessageBus protobuf types for AppSensorMessage dispatch handlers.
• Whether CLI mode is used on production seats (service path confirmed in logs).
• Full list of ETW providers enabled by TraceSession.
• Anti-cheat process dump feature (-- string mentions anti-cheat process name) — not observed in logs.

---

Evidence

• readpe, strings, r2 on services/StutterShark/StutterShark.exe
• logs/StutterShark/PlatformSeatService.log
• logs/startup/stuttersharkSoftwareInstall.log
• logs/GSP/GSConfiguratorPluginCurrent.log, logs/SmithyV2/SmithyController/.../SmithyControllerPlugin.log

StutterSharkResolve.exe

What this program actually does

StutterSharkResolve.exe is an offline post-processing CLI shipped with StutterShark. It resolves call stacks and symbols from stutter-capture artifacts produced by StutterSharkPlugin / TraceSession, using dbghelp (preferring bundled dbghelp_new.dll), DIA (msdia140.dll), and a custom StutterStackWalker. It emits CSV summaries (frames_data.csv, stutters_data.csv) from serialized trace payloads.

It is not a Windows service. Install log copies it beside StutterShark.exe; no runtime log references it in this snapshot.

---

Architecture / control flow (recovered symbols)

main (CLI11 App@CLI)
  └─ StutterSharkResolve.cpp
        ├─ TraceSession / TraceConsumer
        ├─ StutterStackWalker (extends StackWalkerCustom)
        │     ├─ StackWalkerInternal::LoadModuleWithPdbInfo
        │     ├─ StackWalkerInternal::LoadPdbIntoDia
        │     └─ StackWalkerCustom::ShowCallstack
        └─ DeserializeImageAndStacks / DeserializeSystemWideStacks
              → CSV writers (frames_data.csv, stutters_data.csv)

RTTI classes: StutterStackWalker, StackWalkerCustom, TraceConsumer, App@CLI.

Source paths (strings):

• C:\builds\gfn-foundations\stuttershark\Service\StutterSharkResolve.cpp
• C:\builds\gfn-foundations\stuttershark\Plugins\StutterSharkPlugin\TraceSession.cpp
• C:\builds\gfn-foundations\stuttershark\Plugins\StutterSharkPlugin\StackWalker.cpp

PDB: C:\builds\gfn-foundations\stuttershark\out\x64-windows-release\Service\StutterSharkResolve.pdb

---

Symbol resolution stack (strings)

Step	String evidence
Load dbghelp	### Load SYSTEM32 dbghelp_new.dll, ## Load dbghelp.dll failed
SymInit	SymInit: Symbol-SearchPath: '%s', symOptions: %d
DIA path	Using DIA for module: {}, Base: {:#x}..., Loading PDB into DIA has failed
Stack walk	StackWalk64, StackWalk64-Endless-Callstack!
Undecorate	UnDecorateSymbolName, `<unresolved symbol>`
Env	_NT_SYMBOL_PATH

Output artifacts:

• callstack_folded_process_*, callstack_folded_frame_* (folded stack text)
• frames_data.csv — columns include TimestampUTC,FrameIndex,TimestampSecond,DurationMs,SystemCpuUsage,WorkloadCpuUsage
• stutters_data.csv — includes file I/O stats columns (FileTotalRead, FileP95Read, …)

---

External interfaces

Interface	Role
CLI	Usage string present; CLI11 help/error types in RTTI
Local DLLs	Expects dbghelp_new.dll, DIA stack under services/StutterShark/DLL/
Input	Serialized image/stack blobs from trace session ([{}] processes captured for system-wide callstacks)
Output	CSV files in working directory (inferred from string filenames)

No MessageBus, SCM, or network surface in imports.

---

PE / imports (readpe + r2)

Property	Value
Size	1,356,288 bytes
Arch	PE32+ x64 console
Compile	2026-04-22 02:36:25 UTC
Linker	MSVC 14.35
Imports	KERNEL32 (thread/debug APIs: OpenThread, SuspendThread, GetThreadContext, ReadProcessMemory), pdh.dll, ADVAPI32 (GetUserNameA), ole32, OLEAUT32 (DIA/COM)

---

Relationships

Component	Interaction
StutterShark.exe	Produces trace/callstack capture data consumed by this tool
StutterShark/DLL/dbghelp_new.dll	Preferred dbghelp implementation
StutterShark/DLL/msdia140.dll	PDB load via DIA
StutterShark/DLL/symsrv.dll, srcsrv.dll	Symbol server/source indexing (bundled; usage inferred from deployment)

---

Not verified

• Exact CLI flags and required input file layout (only Usage string recovered).
• Whether seat automation invokes this binary post-session or only engineers run it manually.
• Whether pdh.dll import is used on all code paths or dead import from shared build.

---

Evidence

• readpe, strings, r2 on services/StutterShark/StutterSharkResolve.exe
• logs/startup/stuttersharkSoftwareInstall.log (binary deployed)
• Shared plugin strings in StutterShark.exe (StutterStackWalker::*, CSV column names)

StutterSharkTest.exe

What this program actually does

StutterSharkTest.exe is the automated test harness for the StutterShark / Platform Seat Service codebase. It links the production plugin implementations (StutterSharkPlugin, GpuControllerPlugin, VcpuBoostControllerPlugin, UmdPerfCounterPlugin) with Google Test / Google Mock and exercises service startup, CSR parsing, detection logic, GPU controllers, CPUID channel, MessageBus helpers, and CLI config clients.

It is not deployed as a seat service and produces no logs in this snapshot.

---

Test modules (source path strings)

Source file	Focus
Tests/TestPlatformSeatService.cpp	PlatformSeatService GameSeat mode happy-path start/stop, CLI mode happy-path start/stop
Tests/TestDetection.cpp	Stutter detection
Tests/TestGpuController.cpp	GpuControllerPluginImpl compaction, SOPS, frame-time CSV dump
Tests/TestVcpuBoostController.cpp	vCPU boost controller
Tests/TestCPUIDChannel.cpp	CPUID channel / TestPlugin1/2/3 registration
Tests/TestCsrParsingHelper.cpp	CSR config parsing
Tests/TestPubSub.cpp	Pub/sub messaging
Tests/TestRollingWindowStrategy.cpp	Rolling window strategy
Tests/TestFrameWindow.cpp	Frame window utilities
Tests/TestFrameDataCompositor.cpp	Frame data compositor
Tests/TestMbHelper.cpp	MessageBus helper
Tests/CliMode/TestJsonGSConfigClient.cpp	CLI JSON GSConfig client
Tests/Mocks.h	BaseGpuController@TestGpuController@Mocks, MockMessageBus, MockBusMessage

Framework strings: gtest/gtest-matchers.h, gmock/gmock-spec-builders.h, gmock/gmock-actions.h, Catch/Clara types also present in RTTI (mixed test deps in binary).

PDB: C:\builds\gfn-foundations\stuttershark\out\x64-windows-release\Tests\StutterSharkTest.pdb

---

RTTI / types (deep extract sample)

Class	Role
TestPlatformSeatService	End-to-end service tests
BaseGpuController@TestGpuController@Mocks	Mock GPU controller
MockMessageBus, MockBusMessage	Bus isolation
*@Fields@StutterSharkSchema	Same telemetry schema types as production EXE
AppCpuStarvingStuttersCount/Pct@Fields@StutterSharkSchema	Stutter metric field tests

Production plugin class names in strings: StutterSharkPlugin, GpuControllerPlugin, VcpuBoostControllerPlugin.

---

Assertions recovered (strings)

Examples embedded as test expectations:

• service.mEnabledPlugins.size() == 0 → == 3 after plugin load
• plugin->getState() == PluginState::STARTED
• plugin->mPluginErrored == true/false with mLastErrorMessage substring checks for NVML/NVAPI init failures
• GpuControllerPluginImpl - DumpFrametimesToCsv - With Data (and Disabled/Empty/Invalid Directory variants)

---

PE / imports (readpe + r2)

Property	Value
Size	6,737,920 bytes (largest StutterShark binary — includes gtest/gmock + plugins)
Arch	PE32+ x64 console
Compile	2026-04-22 02:36:57 UTC
Entry	0x140427238; main @ 0x14045bb90
Key imports	Same monitoring stack as StutterShark.exe: ETW (ADVAPI32), nvml.dll, pdh.dll, dbghelp.dll, tdh.dll, plus PssCaptureSnapshot / PssQuerySnapshot / PssWalkSnapshot for process snapshot tests

---

Relationships

Component	Interaction
StutterShark.exe	Tests the same PlatformSeatService + plugin code paths
StutterSharkResolve.exe	Shares TraceSession / stack types; no direct test reference in strings
Build tree	C:\builds\gfn-foundations\stuttershark\Tests\

---

Not verified

• Test runner CLI flags (filter/suite selection).
• CI invocation path (not referenced in Asgard seat logs).
• Code coverage of StutterSharkResolve.exe (no strings linking resolve tool tests).

---

Evidence

• readpe, strings, r2 on services/StutterShark/StutterSharkTest.exe
• logs/startup/stuttersharkSoftwareInstall.log (binary deployed to seat)
• Parity strings with StutterShark.exe plugin implementations