| 1 | /* $Id: RTMpGetArraySize-generic.cpp 82968 2020-02-04 10:35:17Z vboxsync $ */
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| 2 | /** @file
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| 3 | * IPRT - Multiprocessor, Generic RTMpGetArraySize.
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| 4 | */
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| 5 |
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| 6 | /*
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| 7 | * Copyright (C) 2010-2020 Oracle Corporation
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| 8 | *
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| 9 | * This file is part of VirtualBox Open Source Edition (OSE), as
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| 10 | * available from http://www.virtualbox.org. This file is free software;
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| 11 | * you can redistribute it and/or modify it under the terms of the GNU
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| 12 | * General Public License (GPL) as published by the Free Software
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| 13 | * Foundation, in version 2 as it comes in the "COPYING" file of the
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| 14 | * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
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| 15 | * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
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| 16 | *
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| 17 | * The contents of this file may alternatively be used under the terms
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| 18 | * of the Common Development and Distribution License Version 1.0
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| 19 | * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
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| 20 | * VirtualBox OSE distribution, in which case the provisions of the
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| 21 | * CDDL are applicable instead of those of the GPL.
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| 22 | *
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| 23 | * You may elect to license modified versions of this file under the
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| 24 | * terms and conditions of either the GPL or the CDDL or both.
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| 25 | */
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| 26 |
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| 27 |
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| 28 | /*********************************************************************************************************************************
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| 29 | * Header Files *
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| 30 | *********************************************************************************************************************************/
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| 31 | #include <iprt/mp.h>
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| 32 | #include "internal/iprt.h"
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| 33 |
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| 34 | #include <iprt/asm.h>
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| 35 | #include <iprt/cpuset.h>
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| 36 |
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| 37 |
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| 38 | RTDECL(uint32_t) RTMpGetArraySize(void)
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| 39 | {
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| 40 | /*
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| 41 | * Cache the result here. This whole point of this function is that it
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| 42 | * will always return the same value, so that should be safe.
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| 43 | *
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| 44 | * Note! Because RTCPUSET may be to small to represent all the CPUs, we
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| 45 | * check with RTMpGetCount() as well.
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| 46 | */
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| 47 | static uint32_t s_cMaxCpus = 0;
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| 48 | uint32_t cCpus = s_cMaxCpus;
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| 49 | if (RT_UNLIKELY(cCpus == 0))
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| 50 | {
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| 51 | RTCPUSET CpuSet;
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| 52 | uint32_t cCpus1 = RTCpuLastIndex(RTMpGetSet(&CpuSet)) + 1;
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| 53 | uint32_t cCpus2 = RTMpGetCount();
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| 54 | cCpus = RT_MAX(cCpus1, cCpus2);
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| 55 | ASMAtomicCmpXchgU32(&s_cMaxCpus, cCpus, 0);
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| 56 | return cCpus;
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| 57 | }
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| 58 | return s_cMaxCpus;
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| 59 |
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| 60 | }
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| 61 | RT_EXPORT_SYMBOL(RTMpGetArraySize);
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| 62 |
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