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Add stencil example

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This commit is contained in:
Matt Pharr
2011-08-03 13:49:02 -07:00
parent a5a133ccce
commit e05b3981d9
8 changed files with 939 additions and 0 deletions
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2
examples/stencil/.gitignore vendored Normal file
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stencil
objs

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examples/stencil/Makefile Normal file
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ARCH = $(shell uname)
TASK_CXX=tasks_pthreads.cpp
TASK_LIB=-lpthread
ifeq ($(ARCH), Darwin)
TASK_CXX=tasks_gcd.cpp
TASK_LIB=
endif
TASK_OBJ=$(addprefix objs/, $(TASK_CXX:.cpp=.o))
CXX=g++ -m64
CXXFLAGS=-Iobjs/ -O3 -Wall
ISPC=ispc
ISPCFLAGS=-O2 --target=sse4x2 --arch=x86-64
default: stencil
.PHONY: dirs clean
dirs:
/bin/mkdir -p objs/
clean:
/bin/rm -rf objs *~ stencil
stencil: dirs objs/stencil.o objs/stencil_serial.o objs/stencil_ispc.o $(TASK_OBJ)
$(CXX) $(CXXFLAGS) -o $@ objs/stencil.o objs/stencil_ispc.o objs/stencil_serial.o $(TASK_OBJ) -lm $(TASK_LIB)
objs/%.o: %.cpp
$(CXX) $< $(CXXFLAGS) -c -o $@
objs/stencil.o: objs/stencil_ispc.h
objs/%_ispc.h objs/%_ispc.o: %.ispc
$(ISPC) $(ISPCFLAGS) $< -o objs/$*_ispc.o -h objs/$*_ispc.h

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/*
Copyright (c) 2010-2011, Intel Corporation
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:
* Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
* Neither the name of Intel Corporation nor the names of its
contributors may be used to endorse or promote products derived from
this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifdef _MSC_VER
#define _CRT_SECURE_NO_WARNINGS
#define NOMINMAX
#pragma warning (disable: 4244)
#pragma warning (disable: 4305)
#endif
#include <stdio.h>
#include <algorithm>
#include <math.h>
#include "../timing.h"
#include "../cpuid.h"
#include "stencil_ispc.h"
using namespace ispc;
// Make sure that the vector ISA used during compilation is supported by
// the processor. The ISPC_TARGET_* macro is set in the ispc-generated
// header file that we include above.
static void
ensureTargetISAIsSupported() {
#if defined(ISPC_TARGET_SSE2)
bool isaSupported = CPUSupportsSSE2();
const char *target = "SSE2";
#elif defined(ISPC_TARGET_SSE4)
bool isaSupported = CPUSupportsSSE4();
const char *target = "SSE4";
#elif defined(ISPC_TARGET_AVX)
bool isaSupported = CPUSupportsAVX();
const char *target = "AVX";
#else
#error "Unknown ISPC_TARGET_* value"
#endif
if (!isaSupported) {
fprintf(stderr, "***\n*** Error: the ispc-compiled code uses the %s instruction "
"set, which isn't\n*** supported by this computer's CPU!\n", target);
fprintf(stderr, "***\n*** Please modify the "
#ifdef _MSC_VER
"MSVC project file "
#else
"Makefile "
#endif
"to select another target (e.g. sse2)\n***\n");
exit(1);
}
}
extern void loop_stencil_serial(int t0, int t1, int x0, int x1,
int y0, int y1, int z0, int z1,
int Nx, int Ny, int Nz,
const float coef[5],
const float vsq[],
float Aeven[], float Aodd[]);
extern "C" {
extern void loop_stencil_ispc(int t0, int t1, int x0, int x1,
int y0, int y1, int z0, int z1,
int Nx, int Ny, int Nz,
const float coef[5],
const float vsq[],
float Aeven[], float Aodd[]);
}
void InitData(int Nx, int Ny, int Nz, float *A[2], float *vsq) {
int offset = 0;
for (int z = 0; z < Nz; ++z)
for (int y = 0; y < Ny; ++y)
for (int x = 0; x < Nx; ++x, ++offset) {
A[0][offset] = (x < Nx / 2) ? x / float(Nx) : y / float(Ny);
A[1][offset] = 0;
vsq[offset] = x*y*z / float(Nx * Ny * Nz);
}
}
int main() {
ensureTargetISAIsSupported();
extern void TasksInit();
TasksInit();
int Nx = 256, Ny = 256, Nz = 256;
int width = 4;
float *Aserial[2], *Aispc[2];
Aserial[0] = new float [Nx * Ny * Nz];
Aserial[1] = new float [Nx * Ny * Nz];
Aispc[0] = new float [Nx * Ny * Nz];
Aispc[1] = new float [Nx * Ny * Nz];
float *vsq = new float [Nx * Ny * Nz];
float coeff[4] = { 0.5, -.25, .125, -.0625 };
InitData(Nx, Ny, Nz, Aispc, vsq);
//
// Compute the image using the ispc implementation; report the minimum
// time of three runs.
//
double minISPC = 1e30;
for (int i = 0; i < 3; ++i) {
reset_and_start_timer();
loop_stencil_ispc(0, 6, width, Nx - width, width, Ny - width,
width, Nz - width, Nx, Ny, Nz, coeff, vsq,
Aispc[0], Aispc[1]);
double dt = get_elapsed_mcycles();
minISPC = std::min(minISPC, dt);
}
printf("[stencil ispc]:\t\t\t[%.3f] million cycles\n", minISPC);
InitData(Nx, Ny, Nz, Aserial, vsq);
//
// And run the serial implementation 3 times, again reporting the
// minimum time.
//
double minSerial = 1e30;
for (int i = 0; i < 3; ++i) {
reset_and_start_timer();
loop_stencil_serial(0, 6, width, Nx-width, width, Ny - width,
width, Nz - width, Nx, Ny, Nz, coeff, vsq,
Aserial[0], Aserial[1]);
double dt = get_elapsed_mcycles();
minSerial = std::min(minSerial, dt);
}
printf("[stencil serial]:\t\t[%.3f] millon cycles\n", minSerial);
printf("\t\t\t\t(%.2fx speedup from ISPC)\n", minSerial/minISPC);
// Check for agreement
int offset = 0;
for (int z = 0; z < Nz; ++z)
for (int y = 0; y < Ny; ++y)
for (int x = 0; x < Nx; ++x, ++offset) {
float error = fabsf((Aserial[1][offset] - Aispc[1][offset]) /
Aserial[1][offset]);
if (error > 1e-4)
printf("Error @ (%d,%d,%d): ispc = %f, serial = %f\n",
x, y, z, Aispc[1][offset], Aserial[1][offset]);
}
return 0;
}

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/*
Copyright (c) 2010-2011, Intel Corporation
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:
* Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
* Neither the name of Intel Corporation nor the names of its
contributors may be used to endorse or promote products derived from
this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
static task void
stencil_step(uniform int x0, uniform int x1,
uniform int y0, uniform int y1,
uniform int z0, uniform int z1,
uniform int Nx, uniform int Ny, uniform int Nz,
uniform const float coef[4], uniform const float vsq[],
uniform const float Ain[], uniform float Aout[]) {
const uniform int Nxy = Nx * Ny;
for (uniform int z = z0; z < z1; ++z) {
for (uniform int y = y0; y < y1; ++y) {
// Assumes that (x1-x0) % programCount == 0
for (uniform int x = x0; x < x1; x += programCount) {
int index = (z * Nxy) + (y * Nx) + x + programIndex;
#define A_cur(x, y, z) Ain[index + (x) + ((y) * Nx) + ((z) * Nxy)]
#define A_next(x, y, z) Aout[index + (x) + ((y) * Nx) + ((z) * Nxy)]
float div = coef[0] * A_cur(0, 0, 0) +
coef[1] * (A_cur(+1, 0, 0) + A_cur(-1, 0, 0) +
A_cur(0, +1, 0) + A_cur(0, -1, 0) +
A_cur(0, 0, +1) + A_cur(0, 0, -1)) +
coef[2] * (A_cur(+2, 0, 0) + A_cur(-2, 0, 0) +
A_cur(0, +2, 0) + A_cur(0, -2, 0) +
A_cur(0, 0, +2) + A_cur(0, 0, -2)) +
coef[3] * (A_cur(+3, 0, 0) + A_cur(-3, 0, 0) +
A_cur(0, +3, 0) + A_cur(0, -3, 0) +
A_cur(0, 0, +3) + A_cur(0, 0, -3));
A_next(0, 0, 0) = 2 * A_cur(0, 0, 0) - A_next(0, 0, 0) +
vsq[index] * div;
}
}
}
}
export void loop_stencil_ispc(uniform int t0, uniform int t1,
uniform int x0, uniform int x1,
uniform int y0, uniform int y1,
uniform int z0, uniform int z1,
uniform int Nx, uniform int Ny, uniform int Nz,
uniform const float coef[4],
uniform const float vsq[],
uniform float Aeven[], uniform float Aodd[])
{
for (uniform int t = t0; t < t1; ++t) {
// Parallelize across cores as well: each task will work on a slice
// of "dz" in the z extent of the volume. (dz=1 seems to work
// better than any larger values.)
uniform int dz = 1;
for (uniform int z = z0; z < z1; z += dz) {
if ((t & 1) == 0)
launch < stencil_step(x0, x1, y0, y1, z, z+dz, Nx, Ny, Nz, coef, vsq,
Aeven, Aodd) >;
else
launch < stencil_step(x0, x1, y0, y1, z, z+dz, Nx, Ny, Nz, coef, vsq,
Aodd, Aeven) >;
}
// We need to wait for all of the launched tasks to finish before
// starting the next iteration.
sync;
}
}

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/*
Copyright (c) 2010-2011, Intel Corporation
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:
* Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
* Neither the name of Intel Corporation nor the names of its
contributors may be used to endorse or promote products derived from
this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
static void
stencil_step(int x0, int x1,
int y0, int y1,
int z0, int z1,
int Nx, int Ny, int Nz,
const float coef[4], const float vsq[],
const float Ain[], float Aout[]) {
int Nxy = Nx * Ny;
for (int z = z0; z < z1; ++z) {
for (int y = y0; y < y1; ++y) {
for (int x = x0; x < x1; ++x) {
int index = (z * Nxy) + (y * Nx) + x;
#define A_cur(x, y, z) Ain[index + (x) + ((y) * Nx) + ((z) * Nxy)]
#define A_next(x, y, z) Aout[index + (x) + ((y) * Nx) + ((z) * Nxy)]
float div = coef[0] * A_cur(0, 0, 0) +
coef[1] * (A_cur(+1, 0, 0) + A_cur(-1, 0, 0) +
A_cur(0, +1, 0) + A_cur(0, -1, 0) +
A_cur(0, 0, +1) + A_cur(0, 0, -1)) +
coef[2] * (A_cur(+2, 0, 0) + A_cur(-2, 0, 0) +
A_cur(0, +2, 0) + A_cur(0, -2, 0) +
A_cur(0, 0, +2) + A_cur(0, 0, -2)) +
coef[3] * (A_cur(+3, 0, 0) + A_cur(-3, 0, 0) +
A_cur(0, +3, 0) + A_cur(0, -3, 0) +
A_cur(0, 0, +3) + A_cur(0, 0, -3));
A_next(0, 0, 0) = 2 * A_cur(0, 0, 0) - A_next(0, 0, 0) +
vsq[index] * div;
}
}
}
}
void loop_stencil_serial(int t0, int t1,
int x0, int x1,
int y0, int y1,
int z0, int z1,
int Nx, int Ny, int Nz,
const float coef[4],
const float vsq[],
float Aeven[], float Aodd[])
{
for (int t = t0; t < t1; ++t) {
if ((t & 1) == 0)
stencil_step(x0, x1, y0, y1, z0, z1, Nx, Ny, Nz, coef, vsq,
Aeven, Aodd);
else
stencil_step(x0, x1, y0, y1, z0, z1, Nx, Ny, Nz, coef, vsq,
Aodd, Aeven);
}
}

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/*
Copyright (c) 2010-2011, Intel Corporation
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:
* Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
* Neither the name of Intel Corporation nor the names of its
contributors may be used to endorse or promote products derived from
this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/* Simple task system implementation for ispc based on Microsoft's
Concurrency Runtime. */
#include <windows.h>
#include <concrt.h>
using namespace Concurrency;
#include <stdint.h>
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
// ispc expects these functions to have C linkage / not be mangled
extern "C" {
void ISPCLaunch(void *f, void *data);
void ISPCSync();
void *ISPCMalloc(int64_t size, int32_t alignment);
void ISPCFree(void *ptr);
}
typedef void (*TaskFuncType)(void *, int, int);
struct TaskInfo {
TaskFuncType ispcFunc;
void *ispcData;
};
// This is a simple implementation that just aborts if more than MAX_TASKS
// are launched. It could easily be extended to be more general...
#define MAX_TASKS 4096
static int taskOffset;
static TaskInfo taskInfo[MAX_TASKS];
static event *events[MAX_TASKS];
static CRITICAL_SECTION criticalSection;
static bool initialized = false;
void
TasksInit() {
InitializeCriticalSection(&criticalSection);
for (int i = 0; i < MAX_TASKS; ++i)
events[i] = new event;
initialized = true;
}
void __cdecl
lRunTask(LPVOID param) {
TaskInfo *ti = (TaskInfo *)param;
// Actually run the task.
// FIXME: like the tasks_gcd.cpp implementation, this is passing bogus
// values for the threadIndex and threadCount builtins, which in turn
// will cause bugs in code that uses those. FWIW this example doesn't
// use them...
int threadIndex = 0;
int threadCount = 1;
ti->ispcFunc(ti->ispcData, threadIndex, threadCount);
// Signal the event that this task is done
int taskNum = ti - &taskInfo[0];
events[taskNum]->set();
}
void
ISPCLaunch(void *func, void *data) {
if (!initialized) {
fprintf(stderr, "You must call TasksInit() before launching tasks.\n");
exit(1);
}
// Get a TaskInfo struct for this task
EnterCriticalSection(&criticalSection);
TaskInfo *ti = &taskInfo[taskOffset++];
assert(taskOffset < MAX_TASKS);
LeaveCriticalSection(&criticalSection);
// And pass it on to the Concurrency Runtime...
ti->ispcFunc = (TaskFuncType)func;
ti->ispcData = data;
CurrentScheduler::ScheduleTask(lRunTask, ti);
}
void ISPCSync() {
if (!initialized) {
fprintf(stderr, "You must call TasksInit() before launching tasks.\n");
exit(1);
}
event::wait_for_multiple(&events[0], taskOffset, true,
COOPERATIVE_TIMEOUT_INFINITE);
for (int i = 0; i < taskOffset; ++i)
events[i]->reset();
taskOffset = 0;
}
void *ISPCMalloc(int64_t size, int32_t alignment) {
return _aligned_malloc(size, alignment);
}
void ISPCFree(void *ptr) {
_aligned_free(ptr);
}

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/*
Copyright (c) 2010-2011, Intel Corporation
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:
* Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
* Neither the name of Intel Corporation nor the names of its
contributors may be used to endorse or promote products derived from
this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/* A simple task system for ispc programs based on Apple's Grand Central
Dispatch. */
#include <dispatch/dispatch.h>
#include <stdio.h>
#include <stdlib.h>
static bool initialized = false;
static dispatch_queue_t gcdQueue;
static dispatch_group_t gcdGroup;
// ispc expects these functions to have C linkage / not be mangled
extern "C" {
void ISPCLaunch(void *f, void *data);
void ISPCSync();
}
struct TaskInfo {
void *func;
void *data;
};
void
TasksInit() {
gcdQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
gcdGroup = dispatch_group_create();
initialized = true;
}
static void
lRunTask(void *ti) {
typedef void (*TaskFuncType)(void *, int, int);
TaskInfo *taskInfo = (TaskInfo *)ti;
TaskFuncType func = (TaskFuncType)(taskInfo->func);
// FIXME: these are bogus values; may cause bugs in code that depends
// on them having unique values in different threads.
int threadIndex = 0;
int threadCount = 1;
// Actually run the task
func(taskInfo->data, threadIndex, threadCount);
// FIXME: taskInfo leaks...
}
void ISPCLaunch(void *func, void *data) {
if (!initialized) {
fprintf(stderr, "You must call TasksInit() before launching tasks.\n");
exit(1);
}
TaskInfo *ti = new TaskInfo;
ti->func = func;
ti->data = data;
dispatch_group_async_f(gcdGroup, gcdQueue, ti, lRunTask);
}
void ISPCSync() {
if (!initialized) {
fprintf(stderr, "You must call TasksInit() before launching tasks.\n");
exit(1);
}
// Wait for all of the tasks in the group to complete before returning
dispatch_group_wait(gcdGroup, DISPATCH_TIME_FOREVER);
}

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/*
Copyright (c) 2010-2011, Intel Corporation
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:
* Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
* Neither the name of Intel Corporation nor the names of its
contributors may be used to endorse or promote products derived from
this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <pthread.h>
#include <semaphore.h>
#include <string.h>
#include <unistd.h>
#include <assert.h>
#include <stdio.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/param.h>
#include <sys/sysctl.h>
#include <stdint.h>
#include <stdlib.h>
#include <errno.h>
#include <vector>
// ispc expects these functions to have C linkage / not be mangled
extern "C" {
void ISPCLaunch(void *f, void *data);
void ISPCSync();
}
static int nThreads;
static pthread_t *threads;
static pthread_mutex_t taskQueueMutex;
static std::vector<std::pair<void *, void *> > taskQueue;
static sem_t *workerSemaphore;
static uint32_t numUnfinishedTasks;
static pthread_mutex_t tasksRunningConditionMutex;
static pthread_cond_t tasksRunningCondition;
static void *lTaskEntry(void *arg);
/** Figure out how many CPU cores there are in the system
*/
static int
lNumCPUCores() {
#if defined(__linux__)
return sysconf(_SC_NPROCESSORS_ONLN);
#else
// Mac
int mib[2];
mib[0] = CTL_HW;
size_t length = 2;
if (sysctlnametomib("hw.logicalcpu", mib, &length) == -1) {
fprintf(stderr, "sysctlnametomib() filed. Guessing 2 cores.");
return 2;
}
assert(length == 2);
int nCores = 0;
size_t size = sizeof(nCores);
if (sysctl(mib, 2, &nCores, &size, NULL, 0) == -1) {
fprintf(stderr, "sysctl() to find number of cores present failed. Guessing 2.");
return 2;
}
return nCores;
#endif
}
void
TasksInit() {
nThreads = lNumCPUCores();
threads = new pthread_t[nThreads];
int err;
if ((err = pthread_mutex_init(&taskQueueMutex, NULL)) != 0) {
fprintf(stderr, "Error creating mutex: %s\n", strerror(err));
exit(1);
}
char name[32];
sprintf(name, "mandelbrot.%d", (int)getpid());
workerSemaphore = sem_open(name, O_CREAT, S_IRUSR|S_IWUSR, 0);
if (!workerSemaphore) {
fprintf(stderr, "Error creating semaphore: %s\n", strerror(err));
exit(1);
}
if ((err = pthread_cond_init(&tasksRunningCondition, NULL)) != 0) {
fprintf(stderr, "Error creating condition variable: %s\n", strerror(err));
exit(1);
}
if ((err = pthread_mutex_init(&tasksRunningConditionMutex, NULL)) != 0) {
fprintf(stderr, "Error creating mutex: %s\n", strerror(err));
exit(1);
}
for (int i = 0; i < nThreads; ++i) {
err = pthread_create(&threads[i], NULL, &lTaskEntry, reinterpret_cast<void *>(i));
if (err != 0) {
fprintf(stderr, "Error creating pthread %d: %s\n", i, strerror(err));
exit(1);
}
}
}
void
ISPCLaunch(void *f, void *d) {
if (threads == NULL) {
fprintf(stderr, "You must call TasksInit() before launching tasks.\n");
exit(1);
}
//
// Acquire mutex, add task
//
int err;
if ((err = pthread_mutex_lock(&taskQueueMutex)) != 0) {
fprintf(stderr, "Error from pthread_mutex_lock: %s\n", strerror(err));
exit(1);
}
taskQueue.push_back(std::make_pair(f, d));
if ((err = pthread_mutex_unlock(&taskQueueMutex)) != 0) {
fprintf(stderr, "Error from pthread_mutex_unlock: %s\n", strerror(err));
exit(1);
}
//
// Update count of number of tasks left to run
//
if ((err = pthread_mutex_lock(&tasksRunningConditionMutex)) != 0) {
fprintf(stderr, "Error from pthread_mutex_lock: %s\n", strerror(err));
exit(1);
}
++numUnfinishedTasks;
if ((err = pthread_mutex_unlock(&tasksRunningConditionMutex)) != 0) {
fprintf(stderr, "Error from pthread_mutex_lock: %s\n", strerror(err));
exit(1);
}
//
// Post to the worker semaphore to wake up worker threads that are
// sleeping waiting for tasks to show up
//
if ((err = sem_post(workerSemaphore)) != 0) {
fprintf(stderr, "Error from sem_post: %s\n", strerror(err));
exit(1);
}
}
static void *
lTaskEntry(void *arg) {
int threadIndex = int(reinterpret_cast<int64_t>(arg));
int threadCount = nThreads;
while (true) {
int err;
if ((err = sem_wait(workerSemaphore)) != 0) {
fprintf(stderr, "Error from sem_wait: %s\n", strerror(err));
exit(1);
}
std::pair<void *, void *> myTask;
//
// Acquire mutex, get task
//
if ((err = pthread_mutex_lock(&taskQueueMutex)) != 0) {
fprintf(stderr, "Error from pthread_mutex_lock: %s\n", strerror(err));
exit(1);
}
if (taskQueue.size() == 0) {
//
// Task queue is empty, go back and wait on the semaphore
//
if ((err = pthread_mutex_unlock(&taskQueueMutex)) != 0) {
fprintf(stderr, "Error from pthread_mutex_unlock: %s\n", strerror(err));
exit(1);
}
continue;
}
myTask = taskQueue.back();
taskQueue.pop_back();
if ((err = pthread_mutex_unlock(&taskQueueMutex)) != 0) {
fprintf(stderr, "Error from pthread_mutex_unlock: %s\n", strerror(err));
exit(1);
}
//
// Do work for _myTask_
//
typedef void (*TaskFunType)(void *, int, int);
TaskFunType func = (TaskFunType)myTask.first;
func(myTask.second, threadIndex, threadCount);
//
// Decrement the number of unfinished tasks counter
//
if ((err = pthread_mutex_lock(&tasksRunningConditionMutex)) != 0) {
fprintf(stderr, "Error from pthread_mutex_lock: %s\n", strerror(err));
exit(1);
}
int unfinished = --numUnfinishedTasks;
if (unfinished == 0) {
//
// Signal the "no more tasks are running" condition if all of
// them are done.
//
int err;
if ((err = pthread_cond_signal(&tasksRunningCondition)) != 0) {
fprintf(stderr, "Error from pthread_cond_signal: %s\n", strerror(err));
exit(1);
}
}
if ((err = pthread_mutex_unlock(&tasksRunningConditionMutex)) != 0) {
fprintf(stderr, "Error from pthread_mutex_lock: %s\n", strerror(err));
exit(1);
}
}
pthread_exit(NULL);
return 0;
}
void ISPCSync() {
if (threads == NULL) {
fprintf(stderr, "You must call TasksInit() before launching tasks.\n");
exit(1);
}
int err;
if ((err = pthread_mutex_lock(&tasksRunningConditionMutex)) != 0) {
fprintf(stderr, "Error from pthread_mutex_lock: %s\n", strerror(err));
exit(1);
}
// As long as there are tasks running, wait on the condition variable;
// doing so causes this thread to go to sleep until someone signals on
// the tasksRunningCondition condition variable.
while (numUnfinishedTasks > 0) {
if ((err = pthread_cond_wait(&tasksRunningCondition,
&tasksRunningConditionMutex)) != 0) {
fprintf(stderr, "Error from pthread_cond_wait: %s\n", strerror(err));
exit(1);
}
}
// We acquire ownership of the condition variable mutex when the above
// pthread_cond_wait returns.
// FIXME: is there a lurking issue here if numUnfinishedTasks gets back
// to zero by the time we get to ISPCSync() and thence we're trying to
// unlock a mutex we don't have a lock on?
if ((err = pthread_mutex_unlock(&tasksRunningConditionMutex)) != 0) {
fprintf(stderr, "Error from pthread_mutex_lock: %s\n", strerror(err));
exit(1);
}
}