Discussion :

[genius4evers]

Bonjour

Comment peut-on lancer un programme codé en C++ plusieurs fois sur un serveur en choisissant chaque fois un processeur du serveur ? (Parallélisme)

Merci par avance
Cordialement

[Astraya]

Salut,


Biensur mais ce n'est pas si simple. tu n'a pas de méthode standard, mais OS spécific.
Regarde du coté de
SetThreadAffinityMask pour windows
pthread_setaffinity_np pour linux

pour les autres il faut regarder la documentation

[genius4evers]

Merci Astraya

[genius4evers]

Code :

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  class Program
    {
        [DllImport("ntdll.dll", CharSet = CharSet.Auto)]
        public static extern uint NtGetCurrentProcessorNumber();
 
        static void Main(string[] args)
        {
 
            //Set affinity to first CPU
            //UIntPtr currentaffinity = ProcessorAffinity.SetThreadAffinity(0);
            //Console.WriteLine("Running on CPU #{0}", NtGetCurrentProcessorNumber());
 
            ////Restore last affinity
            //ProcessorAffinity.SetThreadAffinityMask(currentaffinity);
 
            //Cycle through all logical CPUs
            for (int cpuid = 0; cpuid < Environment.ProcessorCount; cpuid++)
            {
                using (ProcessorAffinity.BeginAffinity(cpuid))
                {
                    Console.WriteLine("Running on CPU #{0}", NtGetCurrentProcessorNumber());
                }
            }
            Console.ReadLine();
 
        }
    }
    public static class ProcessorAffinity
    {
        static class Win32Native
        {
            //GetCurrentThread() returns only a pseudo handle. No need for a SafeHandle here.
            [DllImport("kernel32.dll")]
            public static extern IntPtr GetCurrentThread();
 
            [HostProtectionAttribute(SelfAffectingThreading = true)]
            [DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]
            public static extern UIntPtr SetThreadAffinityMask(IntPtr handle, UIntPtr mask);
 
        }
 
        public struct ProcessorAffinityHelper : IDisposable
        {
            UIntPtr lastaffinity;
 
            internal ProcessorAffinityHelper(UIntPtr lastaffinity)
            {
                this.lastaffinity = lastaffinity;
            }
 
            #region IDisposable Members
 
            public void Dispose()
            {
                if (lastaffinity != UIntPtr.Zero)
                {
                    Win32Native.SetThreadAffinityMask(Win32Native.GetCurrentThread(), lastaffinity);
                    lastaffinity = UIntPtr.Zero;
                }
            }
 
            #endregion
        }
 
        static ulong maskfromids(params int[] ids)
        {
            ulong mask = 0;
            foreach (int id in ids)
            {
                if (id < 0 || id >= Environment.ProcessorCount)
                    throw new ArgumentOutOfRangeException("CPUId", id.ToString());
                mask |= 1UL << id;
            }
            return mask;
        }
 
        /// <summary>
        /// Sets a processor affinity mask for the current thread.
        /// </summary>
        /// <param name="mask">A thread affinity mask where each bit set to 1 specifies a logical processor on which this thread is allowed to run. 
        /// <remarks>Note: a thread cannot specify a broader set of CPUs than those specified in the process affinity mask.</remarks> 
        /// </param>
        /// <returns>The previous affinity mask for the current thread.</returns>
        public static UIntPtr SetThreadAffinityMask(UIntPtr mask)
        {
            UIntPtr lastaffinity = Win32Native.SetThreadAffinityMask(Win32Native.GetCurrentThread(), mask);
            if (lastaffinity == UIntPtr.Zero)
                throw new Win32Exception(Marshal.GetLastWin32Error());
            return lastaffinity;
        }
 
        /// <summary>
        /// Sets the logical CPUs that the current thread is allowed to execute on.
        /// </summary>
        /// <param name="CPUIds">One or more logical processor identifier(s) the current thread is allowed to run on.<remarks>Note: numbering starts from 0.</remarks></param>
        /// <returns>The previous affinity mask for the current thread.</returns>
        public static UIntPtr SetThreadAffinity(params int[] CPUIds)
        {
            return SetThreadAffinityMask(((UIntPtr)maskfromids(CPUIds)));
        }
 
        /// <summary>
        /// Restrict a code block to run on the specified logical CPUs in conjuction with 
        /// the <code>using</code> statement.
        /// </summary>
        /// <param name="CPUIds">One or more logical processor identifier(s) the current thread is allowed to run on.<remarks>Note: numbering starts from 0.</remarks></param>
        /// <returns>A helper structure that will reset the affinity when its Dispose() method is called at the end of the using block.</returns>
        public static ProcessorAffinityHelper BeginAffinity(params int[] CPUIds)
        {
            return new ProcessorAffinityHelper(SetThreadAffinityMask(((UIntPtr)maskfromids(CPUIds))));
        }
 
    }