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igl/external/embree/common/sys/sync/barrier.cpp
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// ======================================================================== //
// Copyright 2009-2014 Intel Corporation //
// //
// Licensed under the Apache License, Version 2.0 (the "License"); //
// you may not use this file except in compliance with the License. //
// You may obtain a copy of the License at //
// //
// http://www.apache.org/licenses/LICENSE-2.0 //
// //
// Unless required by applicable law or agreed to in writing, software //
// distributed under the License is distributed on an "AS IS" BASIS, //
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. //
// See the License for the specific language governing permissions and //
// limitations under the License. //
// ======================================================================== //
#include "barrier.h"
#include "condition.h"
#if defined (__WIN32__)
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
namespace embree
{
struct BarrierSysImplementation
{
__forceinline BarrierSysImplementation ()
: i(0), enterCount(0), exitCount(0), barrierSize(0)
{
events[0] = CreateEvent(NULL, TRUE, FALSE, NULL);
events[1] = CreateEvent(NULL, TRUE, FALSE, NULL);
}
__forceinline ~BarrierSysImplementation ()
{
CloseHandle(events[0]);
CloseHandle(events[1]);
}
__forceinline void init(size_t N)
{
barrierSize = N;
enterCount = N;
exitCount = N;
}
__forceinline void wait()
{
/* every thread entering the barrier decrements this count */
size_t i0 = i;
ssize_t cnt0 = atomic_add(&enterCount,-1);
/* all threads except the last one are wait in the barrier */
if (cnt0 > 1)
{
if (WaitForSingleObject(events[i0], INFINITE) != WAIT_OBJECT_0)
THROW_RUNTIME_ERROR("WaitForSingleObjects failed");
}
/* the last thread starts all threads waiting at the barrier */
else
{
i = 1-i;
enterCount = barrierSize;
if (SetEvent(events[i0]) == 0)
THROW_RUNTIME_ERROR("SetEvent failed");
}
/* every thread leaving the barrier decrements this count */
ssize_t cnt1 = atomic_add(&exitCount,-1);
/* the last thread that left the barrier resets the event again */
if (cnt1 == 1)
{
exitCount = barrierSize;
if (ResetEvent(events[i0]) == 0)
THROW_RUNTIME_ERROR("ResetEvent failed");
}
}
public:
HANDLE events[2];
volatile size_t i;
volatile atomic_t enterCount;
volatile atomic_t exitCount;
size_t barrierSize;
};
}
#else
namespace embree
{
struct BarrierSysImplementation
{
__forceinline BarrierSysImplementation ()
: count(0), barrierSize(0) {}
__forceinline void init(size_t N)
{
count = 0;
barrierSize = N;
}
__forceinline void wait()
{
mutex.lock();
count++;
if (count == barrierSize) {
count = 0;
cond.broadcast();
mutex.unlock();
return;
}
cond.wait(mutex);
mutex.unlock();
return;
}
public:
MutexSys mutex;
ConditionSys cond;
volatile size_t count;
volatile size_t barrierSize;
};
}
#endif
namespace embree
{
BarrierSys::BarrierSys () {
opaque = new BarrierSysImplementation;
}
BarrierSys::~BarrierSys () {
delete (BarrierSysImplementation*) opaque;
}
void BarrierSys::init(size_t count) {
((BarrierSysImplementation*) opaque)->init(count);
}
void BarrierSys::wait() {
((BarrierSysImplementation*) opaque)->wait();
}
LinearBarrierActive::LinearBarrierActive (size_t numThreads_i)
{
numThreads = numThreads_i;
mode = 0;
flag0 = 0;
flag1 = 0;
for (size_t i=0; i<MAX_MIC_THREADS; i++) count0[i] = 0;
for (size_t i=0; i<MAX_MIC_THREADS; i++) count1[i] = 0;
}
void LinearBarrierActive::init(size_t cntr)
{
numThreads = cntr;
mode = 0;
flag0 = 0;
flag1 = 0;
for (size_t i=0; i<cntr; i++) count0[i] = 0;
for (size_t i=0; i<cntr; i++) count1[i] = 0;
}
void LinearBarrierActive::wait (const size_t threadIndex, const size_t __threadCount)
{
waitForThreads(threadIndex,numThreads);
}
void LinearBarrierActive::waitForThreads(const size_t threadIndex, const size_t threadCount)
{
if (mode == 0)
{
if (threadIndex == 0)
{
for (size_t i=0; i<threadCount; i++)
count1[i] = 0;
for (size_t i=1; i<threadCount; i++)
{
unsigned int wait_cycles = MIN_MIC_BARRIER_WAIT_CYCLES;
while (likely(count0[i] == 0))
{
pause(wait_cycles);
}
}
mode = 1;
flag1 = 0;
__memory_barrier();
flag0 = 1;
}
else
{
count0[threadIndex] = 1;
{
unsigned int wait_cycles = MIN_MIC_BARRIER_WAIT_CYCLES;
while (likely(flag0 == 0))
{
pause(wait_cycles);
}
}
}
}
else
{
if (threadIndex == 0)
{
for (size_t i=0; i<threadCount; i++)
count0[i] = 0;
for (size_t i=1; i<threadCount; i++)
{
unsigned int wait_cycles = MIN_MIC_BARRIER_WAIT_CYCLES;
while (likely(count1[i] == 0))
{
pause(wait_cycles);
}
}
mode = 0;
flag0 = 0;
__memory_barrier();
flag1 = 1;
}
else
{
count1[threadIndex] = 1;
{
unsigned int wait_cycles = MIN_MIC_BARRIER_WAIT_CYCLES;
while (likely(flag1 == 0))
{
pause(wait_cycles);
}
}
}
}
}
void LinearBarrierActive::syncWithReduction(const size_t threadIndex,
const size_t threadCount,
void (* reductionFct)(const size_t currentThreadID,
const size_t childThreadID,
void *ptr),
void *ptr)
{
if (mode == 0)
{
if (threadIndex == 0)
{
for (size_t i=0; i<threadCount; i++)
count1[i] = 0;
for (size_t i=1; i<threadCount; i++)
{
unsigned int wait_cycles = MIN_MIC_BARRIER_WAIT_CYCLES;
while (likely(count0[i] == 0))
{
pause(wait_cycles);
}
(*reductionFct)(threadIndex,i,ptr);
}
mode = 1;
flag1 = 0;
__memory_barrier();
flag0 = 1;
}
else
{
count0[threadIndex] = 1;
{
unsigned int wait_cycles = MIN_MIC_BARRIER_WAIT_CYCLES;
while (likely(flag0 == 0))
{
pause(wait_cycles);
}
}
}
}
else
{
if (threadIndex == 0)
{
for (size_t i=0; i<threadCount; i++)
count0[i] = 0;
for (size_t i=1; i<threadCount; i++)
{
unsigned int wait_cycles = MIN_MIC_BARRIER_WAIT_CYCLES;
while (likely(count1[i] == 0))
{
pause(wait_cycles);
}
(*reductionFct)(threadIndex,i,ptr);
}
mode = 0;
flag0 = 0;
__memory_barrier();
flag1 = 1;
}
else
{
count1[threadIndex] = 1;
{
unsigned int wait_cycles = MIN_MIC_BARRIER_WAIT_CYCLES;
while (likely(flag1 == 0))
{
pause(wait_cycles);
}
}
}
}
}
void QuadTreeBarrier::CoreSyncData::init()
{
*(volatile unsigned int*)&threadState[0][0] = 0;
*(volatile unsigned int*)&threadState[1][0] = 0;
mode = 0;
data[0] = 0;
__memory_barrier();
}
void QuadTreeBarrier::CoreSyncData::pause(unsigned int &cycles) {
__pause_cpu_expfalloff(cycles,MAX_MIC_BARRIER_WAIT_CYCLES);
}
void QuadTreeBarrier::CoreSyncData::switchModeAndSendRunSignal(const unsigned int m)
{
//__memory_barrier();
mode = 1 - mode;
__memory_barrier();
*(volatile unsigned int*)&threadState[m][0] = 0;
//__memory_barrier();
}
void QuadTreeBarrier::CoreSyncData::setThreadStateToDone(const unsigned int m, const unsigned int threadID)
{
__memory_barrier();
threadState[m][threadID % 4] = 1;
__memory_barrier();
}
bool QuadTreeBarrier::CoreSyncData::allThreadsDone(const unsigned int m, const unsigned int orMask) {
return (*(volatile unsigned int*)&threadState[m][0] | orMask)== 0x01010101;
}
bool QuadTreeBarrier::CoreSyncData::threadDone(const unsigned int m, const unsigned int threadID) {
return threadState[m][threadID % 4] == 1;
}
void QuadTreeBarrier::CoreSyncData::waitForAllThreadsOnCore(const unsigned int m)
{
unsigned int count = MIN_MIC_BARRIER_WAIT_CYCLES;
while(likely(allThreadsDone(m) == false))
pause(count);
}
void QuadTreeBarrier::CoreSyncData::waitForAllOtherThreadsOnCore(const unsigned int m, const unsigned int threadID)
{
unsigned int count = MIN_MIC_BARRIER_WAIT_CYCLES;
const unsigned int orMask = (unsigned int)1 << ((threadID % 4) * 8);
while(likely(allThreadsDone(m,orMask) == false))
pause(count);
}
QuadTreeBarrier::QuadTreeBarrier()
{
assert(sizeof(CoreSyncData) == 64);
for (size_t i=0;i<MAX_MIC_CORES;i++)
{
data[i].init();
}
}
void QuadTreeBarrier::init(size_t cntr) {
}
void QuadTreeBarrier::CoreSyncData::waitForThreadReceivesRunSignal(const unsigned int m, const unsigned int threadID)
{
unsigned int count = MIN_MIC_BARRIER_WAIT_CYCLES;
while(likely(threadDone(m,threadID) == true))
pause(count);
}
void QuadTreeBarrier::wait(const size_t threadID, const size_t MAX_THREADS_SYNC)
{
if (unlikely(MAX_THREADS_SYNC == 1)) return;
const unsigned int MAX_CORES_SYNC = MAX_THREADS_SYNC >> 2;
const unsigned int coreID = threadID >> 2;
const unsigned int MODE = data[coreID].mode;
// Drain store buffer for NGO stores
//atomic_add((atomic_t*)&data[coreID].data[0],0);
//data[coreID].prefetchEx();
if (threadID == 0)
{
data[0].setThreadStateToDone(MODE,threadID);
// == wait for core 0 ==
data[0].waitForAllThreadsOnCore(MODE);
// == wait for (possible) two children cores
const unsigned int nextCoreID0 = 1;
const unsigned int nextCoreID1 = 2;
data[nextCoreID0].prefetch();
data[nextCoreID1].prefetch();
if (nextCoreID0 < MAX_CORES_SYNC) data[nextCoreID0].waitForAllThreadsOnCore(MODE);
if (nextCoreID1 < MAX_CORES_SYNC) data[nextCoreID1].waitForAllThreadsOnCore(MODE);
data[nextCoreID0].prefetchEx();
data[nextCoreID1].prefetchEx();
// == run signal to core 0 ==
data[0].switchModeAndSendRunSignal(MODE);
// == propagate run signal to core 1,2 ==
if (nextCoreID0 < MAX_CORES_SYNC) data[nextCoreID0].switchModeAndSendRunSignal(MODE);
if (nextCoreID1 < MAX_CORES_SYNC) data[nextCoreID1].switchModeAndSendRunSignal(MODE);
}
else
{
const unsigned int nextCoreID0 = 2*coreID + 1;
const unsigned int nextCoreID1 = 2*coreID + 2;
data[nextCoreID0].prefetch();
data[nextCoreID1].prefetch();
if (threadID % 4 == 0)
{
if (nextCoreID0 < MAX_CORES_SYNC) data[nextCoreID0].waitForAllThreadsOnCore(MODE);
if (nextCoreID1 < MAX_CORES_SYNC) data[nextCoreID1].waitForAllThreadsOnCore(MODE);
}
data[coreID].setThreadStateToDone(MODE,threadID % 4);
data[coreID].waitForThreadReceivesRunSignal(MODE,threadID % 4);
// == propagte run signal to the two children ==
if (threadID % 4 == 0)
{
data[nextCoreID0].prefetchEx();
data[nextCoreID1].prefetchEx();
if (nextCoreID0 < MAX_CORES_SYNC) data[nextCoreID0].switchModeAndSendRunSignal(MODE);
if (nextCoreID1 < MAX_CORES_SYNC) data[nextCoreID1].switchModeAndSendRunSignal(MODE);
}
}
}
void QuadTreeBarrier::syncWithReduction(const size_t threadID,
const size_t MAX_THREADS_SYNC,
void (* reductionFct)(const size_t currentThreadID,
const size_t childThreadID,
void *ptr),
void *ptr)
{
if (unlikely(MAX_THREADS_SYNC == 1)) return;
const unsigned int MAX_CORES_SYNC = MAX_THREADS_SYNC >> 2;
const unsigned int coreID = threadID >> 2;
const unsigned int MODE = data[coreID].mode;
// Drain store buffer for NGO stores
//atomic_add((atomic_t*)&data[coreID].data[0],0);
data[coreID].prefetchEx();
if (threadID == 0)
{
data[0].setThreadStateToDone(MODE,threadID);
// == wait for core 0 ==
data[0].waitForAllThreadsOnCore(MODE);
(*reductionFct)(threadID,threadID+1,ptr);
(*reductionFct)(threadID,threadID+2,ptr);
(*reductionFct)(threadID,threadID+3,ptr);
// == wait for (possible) two children cores
const unsigned int nextCoreID0 = 1;
const unsigned int nextCoreID1 = 2;
const unsigned int nextThreadID0 = nextCoreID0 * 4;
const unsigned int nextThreadID1 = nextCoreID1 * 4;
data[nextCoreID0].prefetch();
data[nextCoreID1].prefetch();
if (nextCoreID0 < MAX_CORES_SYNC)
{
data[nextCoreID0].waitForAllThreadsOnCore(MODE);
(*reductionFct)(threadID,nextThreadID0,ptr);
}
if (nextCoreID1 < MAX_CORES_SYNC)
{
data[nextCoreID1].waitForAllThreadsOnCore(MODE);
(*reductionFct)(threadID,nextThreadID1,ptr);
}
data[nextCoreID0].prefetchEx();
data[nextCoreID1].prefetchEx();
// == run signal to core 0 ==
data[0].switchModeAndSendRunSignal(MODE);
// == propagate run signal to core 1,2 ==
if (nextCoreID0 < MAX_CORES_SYNC) data[nextCoreID0].switchModeAndSendRunSignal(MODE);
if (nextCoreID1 < MAX_CORES_SYNC) data[nextCoreID1].switchModeAndSendRunSignal(MODE);
}
else
{
const unsigned int nextCoreID0 = 2*coreID + 1;
const unsigned int nextCoreID1 = 2*coreID + 2;
const unsigned int nextThreadID0 = nextCoreID0 * 4;
const unsigned int nextThreadID1 = nextCoreID1 * 4;
data[nextCoreID0].prefetch();
data[nextCoreID1].prefetch();
if (threadID % 4 == 0)
{
data[coreID].waitForAllOtherThreadsOnCore(MODE,threadID);
(*reductionFct)(threadID,threadID+1,ptr);
(*reductionFct)(threadID,threadID+2,ptr);
(*reductionFct)(threadID,threadID+3,ptr);
if (nextCoreID0 < MAX_CORES_SYNC)
{
data[nextCoreID0].waitForAllThreadsOnCore(MODE);
(*reductionFct)(threadID,nextThreadID0,ptr);
}
if (nextCoreID1 < MAX_CORES_SYNC)
{
data[nextCoreID1].waitForAllThreadsOnCore(MODE);
(*reductionFct)(threadID,nextThreadID1,ptr);
}
}
data[coreID].setThreadStateToDone(MODE,threadID % 4);
data[coreID].waitForThreadReceivesRunSignal(MODE,threadID % 4);
// == propagte run signal to the two children ==
if (threadID % 4 == 0)
{
data[nextCoreID0].prefetchEx();
data[nextCoreID1].prefetchEx();
if (nextCoreID0 < MAX_CORES_SYNC) data[nextCoreID0].switchModeAndSendRunSignal(MODE);
if (nextCoreID1 < MAX_CORES_SYNC) data[nextCoreID1].switchModeAndSendRunSignal(MODE);
}
}
}
}