src/gromacs/simd/support.cpp

   1 /*
   2  * This file is part of the GROMACS molecular simulation package.
   3  *
   4  * Copyright (c) 2015,2016,2017,2018,2019, by the GROMACS development team, led by
   5  * Mark Abraham, David van der Spoel, Berk Hess, and Erik Lindahl,
   6  * and including many others, as listed in the AUTHORS file in the
   7  * top-level source directory and at http://www.gromacs.org.
   8  *
   9  * GROMACS is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU Lesser General Public License
  11  * as published by the Free Software Foundation; either version 2.1
  12  * of the License, or (at your option) any later version.
  13  *
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  17  * Lesser General Public License for more details.
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  35
  36 /*! \internal \file
  37  *
  38  * \brief Implements SIMD architecture support query routines
  39  *
  40  * \author Erik Lindahl <erik.lindahl@scilifelab.se>
  41  *
  42  * \ingroup module_simd
  43  */
  44
  45 #include "gmxpre.h"
  46
  47 #include "support.h"
  48
  49 #include "config.h"
  50
  51 #include <cstdio>
  52 #include <cstdlib>
  53
  54 #include <map>
  55 #include <string>
  56
  57 #include "gromacs/hardware/cpuinfo.h"
  58 #include "gromacs/hardware/identifyavx512fmaunits.h"
  59 #include "gromacs/utility/stringutil.h"
  60
  61 namespace gmx
  62 {
  63
  64 /*! \cond libapi */
  65
  66 const std::string &
  67 simdString(SimdType s)
  68 {
  69     static const std::map<SimdType, std::string> name =
  70     {
  71         { SimdType::None,           "None"            },
  72         { SimdType::Reference,      "Reference"       },
  73         { SimdType::Generic,        "Generic"         },
  74         { SimdType::X86_Sse2,       "SSE2"            },
  75         { SimdType::X86_Sse4_1,     "SSE4.1"          },
  76         { SimdType::X86_Avx128Fma,  "AVX_128_FMA"     },
  77         { SimdType::X86_Avx,        "AVX_256"         },
  78         { SimdType::X86_Avx2,       "AVX2_256"        },
  79         { SimdType::X86_Avx2_128,   "AVX2_128"        },
  80         { SimdType::X86_Avx512,     "AVX_512"         },
  81         { SimdType::X86_Avx512Knl,  "AVX_512_KNL"     },
  82         { SimdType::X86_Mic,        "X86_MIC"         },
  83         { SimdType::Arm_Neon,       "ARM_NEON"        },
  84         { SimdType::Arm_NeonAsimd,  "ARM_NEON_ASIMD"  },
  85         { SimdType::Ibm_Vmx,        "IBM_VMX"         },
  86         { SimdType::Ibm_Vsx,        "IBM_VSX"         },
  87         { SimdType::Fujitsu_HpcAce, "Fujitsu HPC-ACE" }
  88     };
  89
  90     return name.at(s);
  91 }
  92
  93 namespace
  94 {
  95
  96
  97 //! Helper to detect correct AMD Zen architecture.
  98 bool
  99 cpuIsAmdZen1(const CpuInfo &cpuInfo)
 100 {
 101     // Both Zen/Zen+/Zen2 have family==23
 102     // Model numbers for Zen:
 103     // 1)  Naples, Whitehaven, Summit ridge, and Snowy Owl
 104     // 17) Raven ridge
 105     // Model numbers for Zen+:
 106     // 8)  Pinnacle Ridge
 107     // 24) Picasso
 108     return (cpuInfo.vendor() == gmx::CpuInfo::Vendor::Amd &&
 109             cpuInfo.family() == 23 &&
 110             (cpuInfo.model() == 1 || cpuInfo.model() == 17 ||
 111              cpuInfo.model() == 8 || cpuInfo.model() == 24) );
 112 }
 113
 114 }   // namespace
 115
 116
 117 SimdType
 118 simdSuggested(const CpuInfo &c)
 119 {
 120     SimdType suggested = SimdType::None;
 121
 122     if (c.supportLevel() >= CpuInfo::SupportLevel::Features)
 123     {
 124         switch (c.vendor())
 125         {
 126             case CpuInfo::Vendor::Intel:
 127                 if (c.feature(CpuInfo::Feature::X86_Avx512ER))
 128                 {
 129                     suggested = SimdType::X86_Avx512Knl;
 130                 }
 131                 else if (c.feature(CpuInfo::Feature::X86_Avx512F))
 132                 {
 133                     // If we could not identify the number of AVX512 FMA units we assume 2
 134                     suggested = ( identifyAvx512FmaUnits() == 1 ) ? SimdType::X86_Avx2 : SimdType::X86_Avx512;
 135                 }
 136                 else if (c.feature(CpuInfo::Feature::X86_Avx2))
 137                 {
 138                     suggested = SimdType::X86_Avx2;
 139                 }
 140                 else if (c.feature(CpuInfo::Feature::X86_Avx))
 141                 {
 142                     suggested = SimdType::X86_Avx;
 143                 }
 144                 else if (c.feature(CpuInfo::Feature::X86_Sse4_1))
 145                 {
 146                     suggested = SimdType::X86_Sse4_1;
 147                 }
 148                 else if (c.feature(CpuInfo::Feature::X86_Sse2))
 149                 {
 150                     suggested = SimdType::X86_Sse2;
 151                 }
 152                 break;
 153             case CpuInfo::Vendor::Amd:
 154             case CpuInfo::Vendor::Hygon:
 155                 if (c.feature(CpuInfo::Feature::X86_Avx2))
 156                 {
 157                     // AMD Zen supports 256-bit AVX2, but Zen1 performs better with 128-bit
 158                     // since it can execute two independent such instructions per cycle,
 159                     // and wider SIMD has slightly lower efficiency in GROMACS.
 160                     // However... Zen2 supports full-width execution of 256-bit AVX2,
 161                     // so we only want to apply this hack to Zen/Zen+.
 162                     suggested = cpuIsAmdZen1(c) ? SimdType::X86_Avx2_128 : SimdType::X86_Avx2;
 163                 }
 164                 else if (c.feature(CpuInfo::Feature::X86_Avx))
 165                 {
 166                     // Use 128-bit FMA SIMD if Fma4 flag is set, otherwise plain 256-bit AVX
 167                     if (c.feature(CpuInfo::Feature::X86_Fma4))
 168                     {
 169                         suggested = SimdType::X86_Avx128Fma;
 170                     }
 171                     else
 172                     {
 173                         suggested = SimdType::X86_Avx;
 174                     }
 175                 }
 176                 else if (c.feature(CpuInfo::Feature::X86_Sse4_1))
 177                 {
 178                     suggested = SimdType::X86_Sse4_1;
 179                 }
 180                 else if (c.feature(CpuInfo::Feature::X86_Sse2))
 181                 {
 182                     suggested = SimdType::X86_Sse2;
 183                 }
 184
 185                 break;
 186             case CpuInfo::Vendor::Arm:
 187                 if (c.feature(CpuInfo::Feature::Arm_NeonAsimd))
 188                 {
 189                     suggested = SimdType::Arm_NeonAsimd;
 190                 }
 191                 else if (c.feature(CpuInfo::Feature::Arm_Neon))
 192                 {
 193                     suggested = SimdType::Arm_Neon;
 194                 }
 195                 break;
 196             case CpuInfo::Vendor::Ibm:
 197                 if (c.feature(CpuInfo::Feature::Ibm_Vsx))
 198                 {
 199                     suggested = SimdType::Ibm_Vsx;
 200                 }
 201                 else if (c.feature(CpuInfo::Feature::Ibm_Vmx))
 202                 {
 203                     suggested = SimdType::Ibm_Vmx;
 204                 }
 205                 break;
 206             case CpuInfo::Vendor::Fujitsu:
 207                 if (c.feature(CpuInfo::Feature::Fujitsu_HpcAce))
 208                 {
 209                     suggested = SimdType::Fujitsu_HpcAce;
 210                 }
 211                 break;
 212             default:
 213                 break;
 214         }
 215     }
 216     return suggested;
 217 }
 218
 219 SimdType
 220 simdCompiled()
 221 {
 222 #if GMX_SIMD_X86_AVX_512_KNL
 223     return SimdType::X86_Avx512Knl;
 224 #elif GMX_SIMD_X86_AVX_512
 225     return SimdType::X86_Avx512;
 226 #elif GMX_SIMD_X86_MIC
 227     return SimdType::X86_Mic;
 228 #elif GMX_SIMD_X86_AVX2_256
 229     return SimdType::X86_Avx2;
 230 #elif GMX_SIMD_X86_AVX2_128
 231     return SimdType::X86_Avx2_128;
 232 #elif GMX_SIMD_X86_AVX_256
 233     return SimdType::X86_Avx;
 234 #elif GMX_SIMD_X86_AVX_128_FMA
 235     return SimdType::X86_Avx128Fma;
 236 #elif GMX_SIMD_X86_SSE4_1
 237     return SimdType::X86_Sse4_1;
 238 #elif GMX_SIMD_X86_SSE2
 239     return SimdType::X86_Sse2;
 240 #elif GMX_SIMD_ARM_NEON
 241     return SimdType::Arm_Neon;
 242 #elif GMX_SIMD_ARM_NEON_ASIMD
 243     return SimdType::Arm_NeonAsimd;
 244 #elif GMX_SIMD_IBM_VMX
 245     return SimdType::Ibm_Vmx;
 246 #elif GMX_SIMD_IBM_VSX
 247     return SimdType::Ibm_Vsx;
 248 #elif GMX_SIMD_SPARC64_HPC_ACE
 249     return SimdType::Fujitsu_HpcAce;
 250 #elif GMX_SIMD_REFERENCE
 251     return SimdType::Reference;
 252 #else
 253     return SimdType::None;
 254 #endif
 255 }
 256
 257 bool
 258 simdCheck(gmx::SimdType    wanted,
 259           FILE *           log,
 260           bool             warnToStdErr)
 261 {
 262     SimdType             compiled  = simdCompiled();
 263
 264     gmx::TextLineWrapper wrapper;
 265     std::string          logMsg;
 266     std::string          warnMsg;
 267
 268     wrapper.settings().setLineLength(78);
 269
 270     if (compiled == SimdType::X86_Avx2 && wanted == SimdType::X86_Avx512)
 271     {
 272         logMsg = wrapper.wrapToString(formatString("Highest SIMD level requested by all nodes in run: %s\n"
 273                                                    "SIMD instructions selected at compile time:       %s\n"
 274                                                    "This program was compiled for different hardware than you are running on, "
 275                                                    "which could influence performance. This build might have been configured on "
 276                                                    "a login node with only a single AVX-512 FMA unit (in which case AVX2 is faster), "
 277                                                    "while the node you are running on has dual AVX-512 FMA units.",
 278                                                    simdString(wanted).c_str(), simdString(compiled).c_str()));
 279         warnMsg = wrapper.wrapToString(formatString("Compiled SIMD: %s, but for this host/run %s might be better (see log).",
 280                                                     simdString(compiled).c_str(), simdString(wanted).c_str()));
 281     }
 282     else if (compiled == SimdType::X86_Avx512 && wanted == SimdType::X86_Avx2 && identifyAvx512FmaUnits() == 1)
 283     {
 284         // The reason for explicitly checking the number of FMA units above is to avoid triggering
 285         // this conditional if the AVX2 SIMD was requested by some other node in a heterogeneous MPI run.
 286         logMsg = wrapper.wrapToString(formatString("Highest SIMD level requested by all nodes in run: %s\n"
 287                                                    "SIMD instructions selected at compile time:       %s\n"
 288                                                    "This program was compiled for different hardware than you are running on, "
 289                                                    "which could influence performance."
 290                                                    "This host supports AVX-512, but since it only has 1 AVX-512"
 291                                                    "FMA unit, it would be faster to use AVX2 instead.",
 292                                                    simdString(wanted).c_str(), simdString(compiled).c_str()));
 293         warnMsg = wrapper.wrapToString(formatString("Compiled SIMD: %s, but for this host/run %s might be better (see log).",
 294                                                     simdString(compiled).c_str(), simdString(wanted).c_str()));
 295     }
 296     else if (compiled == SimdType::X86_Avx2 && wanted == SimdType::X86_Avx2_128)
 297     {
 298         // Wanted SimdType::X86_Avx2_128 can only be the AMD Zen architecture.
 299         // AVX2_256 is only up to a few percent slower than AVX2_128
 300         // in both single and double precision. AVX2_256 is slightly
 301         // faster with nonbondeds and PME on a GPU. Don't warn the user.
 302     }
 303     else if (compiled > wanted && !(compiled == SimdType::X86_Avx && wanted == SimdType::X86_Avx128Fma))
 304     {
 305         // Normally it is close to catastrophic if the compiled SIMD type is larger than
 306         // the supported one, but AVX128Fma is an exception: AMD CPUs will (strongly) prefer
 307         // AVX128Fma, but they will work fine with AVX too. Thus, make an exception for this.
 308         logMsg = wrapper.wrapToString(formatString("Highest SIMD level requested by all nodes in run: %s\n"
 309                                                    "SIMD instructions selected at compile time:       %s\n"
 310                                                    "Compiled SIMD newer than requested; program might crash.",
 311                                                    simdString(wanted).c_str(), simdString(compiled).c_str()));
 312         warnMsg = logMsg;
 313     }
 314     else if (wanted != compiled)
 315     {
 316         // This warning will also occur if compiled is X86_Avx and wanted is X86_Avx128Fma
 317         logMsg = wrapper.wrapToString(formatString("Highest SIMD level requested by all nodes in run: %s\n"
 318                                                    "SIMD instructions selected at compile time:       %s\n"
 319                                                    "This program was compiled for different hardware than you are running on, "
 320                                                    "which could influence performance.",
 321                                                    simdString(wanted).c_str(), simdString(compiled).c_str()));
 322         warnMsg = wrapper.wrapToString(formatString("Compiled SIMD: %s, but for this host/run %s might be better (see log).",
 323                                                     simdString(compiled).c_str(), simdString(wanted).c_str()));
 324     }
 325
 326     if (!logMsg.empty() && log != nullptr)
 327     {
 328         fprintf(log, "%s\n", logMsg.c_str());
 329     }
 330     if (!warnMsg.empty() && warnToStdErr)
 331     {
 332         fprintf(stderr, "%s\n", warnMsg.c_str());
 333     }
 334
 335     return (wanted == compiled);
 336 }
 337
 338 /*! \endcond */
 339
 340 }  // namespace gmx