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Increase the default number of IO queues on larger machines #56501

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Merged
merged 2 commits into from
Jul 1, 2024
Merged

Increase the default number of IO queues on larger machines #56501

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31afef5
Increase the default number of IO queues on larger machines
Jun 26, 2024
a007656
Update comment, simplify calculation
Jun 28, 2024
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17 changes: 17 additions & 0 deletions src/Servers/Kestrel/Transport.Sockets/src/Internal/IOQueue.cs
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Expand Up @@ -10,6 +10,8 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Transport.Sockets.Internal;

internal sealed class IOQueue : PipeScheduler, IThreadPoolWorkItem
{
public static readonly int DefaultCount = DetermineDefaultCount();

private readonly ConcurrentQueue<Work> _workItems = new ConcurrentQueue<Work>();
private int _doingWork;

Expand Down Expand Up @@ -73,4 +75,19 @@ public Work(Action<object?> callback, object? state)
State = state;
}
}

private static int DetermineDefaultCount()
{
// Since each IOQueue schedules one work item to process its work, the number of IOQueues determines the maximum
// parallelism of processing work queued to IOQueues. The default number below is based on the processor count and tries
// to use a high-enough number for that to not be a significant limiting factor for throughput.

int processorCount = Environment.ProcessorCount;
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Nit:

Suggested change
int processorCount = Environment.ProcessorCount;
var processorCount = Environment.ProcessorCount;

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Isn't the explicit type preferred in this case? I thought that was the case in the runtime repo anyway, not sure about the guidelines in this repo.

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Even if var is allowed in this repo, how is it better here?

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"var all the things" is convention here (personally I prefer the explicit type, but to be consistent w/ the codebase -> var).

if (OperatingSystem.IsWindows() || processorCount <= 32)
{
return Math.Min(processorCount, 16);
}

return (processorCount + 1) / 2;
}
}
4 changes: 2 additions & 2 deletions src/Servers/Kestrel/Transport.Sockets/src/SocketConnectionFactoryOptions.cs
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Expand Up @@ -33,9 +33,9 @@ internal SocketConnectionFactoryOptions(SocketTransportOptions transportOptions)
/// The number of I/O queues used to process requests. Set to 0 to directly schedule I/O to the ThreadPool.
/// </summary>
/// <remarks>
/// Defaults to <see cref="Environment.ProcessorCount" /> rounded down and clamped between 1 and 16.
/// Defaults to a value based on and limited to <see cref="Environment.ProcessorCount" />.
/// </remarks>
public int IOQueueCount { get; set; } = Math.Min(Environment.ProcessorCount, 16);
public int IOQueueCount { get; set; } = Internal.IOQueue.DefaultCount;

/// <summary>
/// Wait until there is data available to allocate a buffer. Setting this to false can increase throughput at the cost of increased memory usage.
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4 changes: 2 additions & 2 deletions src/Servers/Kestrel/Transport.Sockets/src/SocketTransportOptions.cs
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Expand Up @@ -28,9 +28,9 @@ static SocketTransportOptions()
/// The number of I/O queues used to process requests. Set to 0 to directly schedule I/O to the ThreadPool.
/// </summary>
/// <remarks>
/// Defaults to <see cref="Environment.ProcessorCount" /> rounded down and clamped between 1 and 16.
/// Defaults to a value based on and limited to <see cref="Environment.ProcessorCount" />.
/// </remarks>
public int IOQueueCount { get; set; } = Math.Min(Environment.ProcessorCount, 16);
public int IOQueueCount { get; set; } = Internal.IOQueue.DefaultCount;

/// <summary>
/// Wait until there is data available to allocate a buffer. Setting this to false can increase throughput at the cost of increased memory usage.
Expand Down
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