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Fluids: improve multithreaded CPU usage. 

Fixes for clamp-omp, fewer shared variables, fix some cases of threads writing
to the same memory location. Issue found by Jens Verwiebe, who reports 30%
speedup with 16 core CPU, when using this with a recent clang-omp version.
This commit is contained in:
Brecht Van Lommel 2016-10-02 15:43:02 +02:00 committed by Sergey Sharybin
parent f6d2981ffb
commit 34b09852fd
2 changed files with 19 additions and 12 deletions
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2
intern/elbeem/intern/solver_class.h
View File

@ -332,7 +332,7 @@ class LbmFsgrSolver :
void debugMarkCellCall(int level, int vi,int vj,int vk);
// loop over grid, stream&collide update
void mainLoop(int lev);
void mainLoop(const int lev);
// change time step size
void adaptTimestep();
//! init mObjectSpeeds for current parametrization

29
intern/elbeem/intern/solver_main.cpp
View File

@ -355,7 +355,7 @@ void LbmFsgrSolver::fineAdvance()
//! fine step function
/*****************************************************************************/
void
LbmFsgrSolver::mainLoop(int lev)
LbmFsgrSolver::mainLoop(const int lev)
{
// loops over _only inner_ cells -----------------------------------------------------------------------------------
@ -376,13 +376,16 @@ LbmFsgrSolver::mainLoop(int lev)
// main loop region
const bool doReduce = true;
const int gridLoopBound=1;
const int gDebugLevel = ::gDebugLevel;
int calcNumInvIfCells = 0;
LbmFloat calcInitialMass = 0;
GRID_REGION_INIT();
#if PARALLEL==1
#pragma omp parallel default(shared) num_threads(mNumOMPThreads) \
#pragma omp parallel default(none) num_threads(mNumOMPThreads) \
reduction(+: \
calcCurrentMass,calcCurrentVolume, \
calcCellsFilled,calcCellsEmptied, \
calcNumUsedCells )
calcNumUsedCells,calcNumInvIfCells,calcInitialMass)
GRID_REGION_START();
#else // PARALLEL==1
GRID_REGION_START();
@ -468,7 +471,7 @@ LbmFsgrSolver::mainLoop(int lev)
calcCurrentMass += iniRho;
calcCurrentVolume += 1.0;
calcNumUsedCells++;
mInitialMass += iniRho;
calcInitialMass += iniRho;
// dont treat cell until next step
continue;
}
@ -479,7 +482,7 @@ LbmFsgrSolver::mainLoop(int lev)
if(isnotValid) {
// remove fluid cells, shouldnt be here anyway
LbmFloat fluidRho = m[0]; FORDF1 { fluidRho += m[l]; }
mInitialMass -= fluidRho;
calcInitialMass -= fluidRho;
const LbmFloat iniRho = 0.0;
RAC(tcel, dMass) = RAC(tcel, dFfrac) = iniRho;
RAC(tcel, dFlux) = FLUX_INIT;
@ -608,8 +611,8 @@ LbmFsgrSolver::mainLoop(int lev)
// read distribution funtions of adjacent cells = stream step
DEFAULT_STREAM;
if((nbored & CFFluid)==0) { newFlag |= CFNoNbFluid; mNumInvIfCells++; }
if((nbored & CFEmpty)==0) { newFlag |= CFNoNbEmpty; mNumInvIfCells++; }
if((nbored & CFFluid)==0) { newFlag |= CFNoNbFluid; calcNumInvIfCells++; }
if((nbored & CFEmpty)==0) { newFlag |= CFNoNbEmpty; calcNumInvIfCells++; }
// calculate mass exchange for interface cells
LbmFloat myfrac = RAC(ccel,dFfrac);
@ -809,7 +812,7 @@ LbmFsgrSolver::mainLoop(int lev)
// fill if cells in inflow region
if(myfrac<0.5) {
mass += 0.25;
mInitialMass += 0.25;
calcInitialMass += 0.25;
}
const int OId = oldFlag>>24;
const LbmVec vel(mObjectSpeeds[OId]);
@ -1013,7 +1016,7 @@ LbmFsgrSolver::mainLoop(int lev)
if( (mass) <= (rho * ( -FSGR_MAGICNR)) ) { ifemptied = 1; }
if(oldFlag & (CFMbndOutflow)) {
mInitialMass -= mass;
calcInitialMass -= mass;
mass = myfrac = 0.0;
iffilled = 0; ifemptied = 1;
}
@ -1105,6 +1108,8 @@ LbmFsgrSolver::mainLoop(int lev)
mNumFilledCells = calcCellsFilled;
mNumEmptiedCells = calcCellsEmptied;
mNumUsedCells = calcNumUsedCells;
mNumInvIfCells += calcNumInvIfCells;
mInitialMass += calcInitialMass;
}
@ -1115,13 +1120,14 @@ LbmFsgrSolver::preinitGrids()
const int lev = mMaxRefine;
const bool doReduce = false;
const int gridLoopBound=0;
const int gDebugLevel = ::gDebugLevel;
// preinit both grids
for(int s=0; s<2; s++) {
GRID_REGION_INIT();
#if PARALLEL==1
#pragma omp parallel default(shared) num_threads(mNumOMPThreads) \
#pragma omp parallel default(none) num_threads(mNumOMPThreads) \
reduction(+: \
calcCurrentMass,calcCurrentVolume, \
calcCellsFilled,calcCellsEmptied, \
@ -1155,10 +1161,11 @@ LbmFsgrSolver::standingFluidPreinit()
const int lev = mMaxRefine;
const bool doReduce = false;
const int gridLoopBound=1;
const int gDebugLevel = ::gDebugLevel;
GRID_REGION_INIT();
#if PARALLEL==1
#pragma omp parallel default(shared) num_threads(mNumOMPThreads) \
#pragma omp parallel default(none) num_threads(mNumOMPThreads) \
reduction(+: \
calcCurrentMass,calcCurrentVolume, \
calcCellsFilled,calcCellsEmptied, \