62 lines
2.6 KiB
C#
62 lines
2.6 KiB
C#
//------------------------------------------------------------------------------
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// <copyright file="SystemInfo.cs" company="Microsoft">
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// Copyright (c) Microsoft Corporation. All rights reserved.
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// </copyright>
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//------------------------------------------------------------------------------
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namespace System.Web.Util {
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internal static class SystemInfo {
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static int _trueNumberOfProcessors;
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static internal int GetNumProcessCPUs() {
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if (_trueNumberOfProcessors == 0) {
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UnsafeNativeMethods.SYSTEM_INFO si;
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UnsafeNativeMethods.GetSystemInfo(out si);
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if (si.dwNumberOfProcessors == 1) {
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_trueNumberOfProcessors = 1;
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}
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else {
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// KERNEL32.DLL:GetCurrentProcess() always returns -1 under NT
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// Note: not really a handle (no need to CloseHandle())
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IntPtr processHandle = UnsafeNativeMethods.INVALID_HANDLE_VALUE;
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IntPtr processAffinityMask;
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IntPtr systemAffinityMask;
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int returnCode = UnsafeNativeMethods.GetProcessAffinityMask(
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processHandle, out processAffinityMask, out systemAffinityMask);
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if (returnCode == 0) {
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_trueNumberOfProcessors = 1;
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}
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else {
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// if cpu affinity is set to a single processor busy waiting is a waste of time
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int numProcessors = 0;
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if (IntPtr.Size == 4) {
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uint mask = (uint) processAffinityMask;
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for (; mask != 0; mask >>= 1) {
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if ((mask & 1) == 1) {
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++numProcessors;
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}
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}
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}
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else {
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ulong mask = (ulong) processAffinityMask;
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for (; mask != 0; mask >>= 1) {
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if ((mask & 1) == 1) {
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++numProcessors;
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}
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}
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}
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_trueNumberOfProcessors = numProcessors;
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}
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}
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}
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Debug.Assert(_trueNumberOfProcessors > 0);
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return _trueNumberOfProcessors;
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}
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}
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}
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