Table of Contents

Interface ICrossGpuBarrier

Namespace
DotCompute.Abstractions.Barriers
Assembly
DotCompute.Abstractions.dll

Cross-GPU barrier for synchronizing multiple devices in distributed Ring Kernel systems. Enables sub-10μs multi-device coordination with HLC-based temporal ordering.

public interface ICrossGpuBarrier : IDisposable
Inherited Members
Extension Methods

Remarks

Cross-GPU barriers provide three synchronization modes:

  • P2P Memory Mode: GPU-GPU direct signaling via peer-to-peer memory writes (fastest)
  • CUDA Event Mode: Event-based synchronization using cudaEventWaitExternal
  • CPU Fallback Mode: Host-mediated synchronization for non-P2P capable systems

Performance Targets:

  • P2P Mode: <2μs (direct GPU memory writes)
  • Event Mode: <5μs (CUDA event synchronization)
  • CPU Mode: <50μs (host-mediated roundtrip)

Integration with HLC:

Each barrier arrival is timestamped with HLC to enable:

  • Causal analysis of synchronization patterns
  • Distributed debugging of barrier deadlocks
  • Timeout detection with happened-before relationships

Properties

BarrierId

Gets the unique identifier for this barrier.

string BarrierId { get; }

Property Value

string

Mode

Gets the synchronization mode used by this barrier.

CrossGpuBarrierMode Mode { get; }

Property Value

CrossGpuBarrierMode

ParticipantCount

Gets the number of participating GPUs in this barrier.

int ParticipantCount { get; }

Property Value

int

Methods

ArriveAndWaitAsync(int, HlcTimestamp, TimeSpan, CancellationToken)

Arrives at the barrier from the specified GPU and waits for all participants.

Task<CrossGpuBarrierResult> ArriveAndWaitAsync(int gpuId, HlcTimestamp arrivalTimestamp, TimeSpan timeout, CancellationToken cancellationToken = default)

Parameters

gpuId int

GPU device ID (0-based index).

arrivalTimestamp HlcTimestamp

HLC timestamp of arrival for causality tracking.

timeout TimeSpan

Maximum wait time before timing out.

cancellationToken CancellationToken

Cancellation token for aborting wait.

Returns

Task<CrossGpuBarrierResult>

Barrier result containing:

  • Success/timeout/failure status
  • Release timestamp (max HLC of all arrivals)
  • Arrival timestamps from all participants

Exceptions

ArgumentOutOfRangeException

Thrown if gpuId is invalid.

BarrierTimeoutException

Thrown if barrier times out.

ObjectDisposedException

Thrown if barrier has been disposed.

ArriveAsync(int, HlcTimestamp)

Arrives at the barrier without waiting (split-phase barrier).

Task<CrossGpuBarrierPhase> ArriveAsync(int gpuId, HlcTimestamp arrivalTimestamp)

Parameters

gpuId int

GPU device ID.

arrivalTimestamp HlcTimestamp

HLC timestamp of arrival.

Returns

Task<CrossGpuBarrierPhase>

Barrier phase token for later wait operation.

Exceptions

ArgumentOutOfRangeException

Thrown if gpuId is invalid.

ObjectDisposedException

Thrown if barrier has been disposed.

GetStatus()

Gets the current barrier status without blocking.

CrossGpuBarrierStatus GetStatus()

Returns

CrossGpuBarrierStatus

Status including arrival count and HLC timestamps.

ResetAsync()

Resets the barrier for reuse (increments generation counter).

Task ResetAsync()

Returns

Task

Remarks

All participants must have completed the current barrier phase before resetting. Reset increments the generation counter to prevent ABA problems in wait loops.

Exceptions

InvalidOperationException

Thrown if barrier is still in use.

ObjectDisposedException

Thrown if barrier has been disposed.

WaitAsync(CrossGpuBarrierPhase, TimeSpan, CancellationToken)

Waits for barrier completion using a phase token from prior arrival.

Task<CrossGpuBarrierResult> WaitAsync(CrossGpuBarrierPhase phase, TimeSpan timeout, CancellationToken cancellationToken = default)

Parameters

phase CrossGpuBarrierPhase

Phase token from ArriveAsync(int, HlcTimestamp).

timeout TimeSpan

Maximum wait time.

cancellationToken CancellationToken

Cancellation token.

Returns

Task<CrossGpuBarrierResult>

Barrier result with release timestamp and participant arrivals.

Exceptions

BarrierTimeoutException

Thrown if barrier times out.

ObjectDisposedException

Thrown if barrier has been disposed.

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