Cuda 如何在多个内核启动之间同步全局内存?
我想在FOR循环(伪)中多次启动以下内核:Cuda 如何在多个内核启动之间同步全局内存?,cuda,Cuda,我想在FOR循环(伪)中多次启动以下内核: \uuuu全局\uuuuu无效内核(t\u dev是全局mem中的输入数组){ __共享预处理tt[块尺寸]; if(thid
\uuuu全局\uuuuu无效内核(t\u dev是全局mem中的输入数组){
__共享预处理tt[块尺寸];
if(thid
从概念上讲,我所做的是从t_dev读取值。修改它们,并再次向global mem写信!然后我再次启动同一个内核
为什么我显然需要u threadfence或u syncthread
否则结果会出错,因为当同一内核再次启动时,内存写入没有完成。这里就是这样,我的GTX580启用了设备重叠
但是为什么在下一个内核启动时全局mem写入没有完成。。。这是因为设备重叠还是因为它总是这样?我想,当我们一个接一个地启动内核时,mem的写入/读取在一个内核之后完成…:-)
谢谢你的回答
一些代码:
for(int kernelAIdx = 0; kernelAIdx < loops; kernelAIdx++){
proxGPU::sorProxContactOrdered_1threads_StepA_kernelWrap<PREC,SorProxSettings1>(
mu_dev,x_new_dev,T_dev,x_old_dev,d_dev,
t_dev,
kernelAIdx,
pConvergedFlag_dev,
m_absTOL,m_relTOL);
proxGPU::sorProx_StepB_kernelWrap<PREC,SorProxSettings1>(
t_dev,
T_dev,
x_new_dev,
kernelAIdx
);
}
for(int-kernelAIdx=0;kernelAIdx
这是循环中的两个内核,t_dev和x_new_dev,从步骤A移动到步骤B
内核A如下所示:
template<typename PREC, int THREADS_PER_BLOCK, int BLOCK_DIM, int PROX_PACKAGES, typename TConvexSet>
__global__ void sorProxContactOrdered_1threads_StepA_kernel(
utilCuda::Matrix<PREC> mu_dev,
utilCuda::Matrix<PREC> y_dev,
utilCuda::Matrix<PREC> T_dev,
utilCuda::Matrix<PREC> x_old_dev,
utilCuda::Matrix<PREC> d_dev,
utilCuda::Matrix<PREC> t_dev,
int kernelAIdx,
int maxNContacts,
bool * convergedFlag_dev,
PREC _absTOL, PREC _relTOL){
//__threadfence() HERE OR AT THE END; THEN IT WORKS???? WHY
// Assumend 1 Block, with THREADS_PER_BLOCK Threads and Column Major Matrix T_dev
int thid = threadIdx.x;
int m = min(maxNContacts*PROX_PACKAGE_SIZE, BLOCK_DIM); // this is the actual size of the diagonal block!
int i = kernelAIdx * BLOCK_DIM;
int ii = i + thid;
//First copy x_old_dev in shared
__shared__ PREC xx[BLOCK_DIM]; // each thread writes one element, if its in the limit!!
__shared__ PREC tt[BLOCK_DIM];
if(thid < m){
xx[thid] = x_old_dev.data[ii];
tt[thid] = t_dev.data[ii];
}
__syncthreads();
PREC absTOL = _absTOL;
PREC relTOL = _relTOL;
int jj;
//PREC T_iijj;
//Offset the T_dev_ptr to the start of the Block
PREC * T_dev_ptr = PtrElem_ColM(T_dev,i,i);
PREC * mu_dev_ptr = &mu_dev.data[PROX_PACKAGES*kernelAIdx];
__syncthreads();
for(int j_t = 0; j_t < m ; j_t+=PROX_PACKAGE_SIZE){
//Select the number of threads we need!
// Here we process one [m x PROX_PACKAGE_SIZE] Block
// First Normal Direction ==========================================================
jj = i + j_t;
__syncthreads();
if( ii == jj ){ // select thread on the diagonal ...
PREC x_new_n = (d_dev.data[ii] + tt[thid]);
//Prox Normal!
if(x_new_n <= 0.0){
x_new_n = 0.0;
}
/* if( !checkConverged(x_new,xx[thid],absTOL,relTOL)){
*convergedFlag_dev = 0;
}*/
xx[thid] = x_new_n;
tt[thid] = 0.0;
}
// all threads not on the diagonal fall into this sync!
__syncthreads();
// Select only m threads!
if(thid < m){
tt[thid] += T_dev_ptr[thid] * xx[j_t];
}
// ====================================================================================
// wee need to syncronize here because one threads finished lambda_t2 with shared mem tt, which is updated from another thread!
__syncthreads();
// Second Tangential Direction ==========================================================
jj++;
__syncthreads();
if( ii == jj ){ // select thread on diagonal, one thread finishs T1 and T2 directions.
// Prox tangential
PREC lambda_T1 = (d_dev.data[ii] + tt[thid]);
PREC lambda_T2 = (d_dev.data[ii+1] + tt[thid+1]);
PREC radius = (*mu_dev_ptr) * xx[thid-1];
PREC absvalue = sqrt(lambda_T1*lambda_T1 + lambda_T2*lambda_T2);
if(absvalue > radius){
lambda_T1 = (lambda_T1 * radius ) / absvalue;
lambda_T2 = (lambda_T2 * radius ) / absvalue;
}
/*if( !checkConverged(lambda_T1,xx[thid],absTOL,relTOL)){
*convergedFlag_dev = 0;
}
if( !checkConverged(lambda_T2,xx[thid+1],absTOL,relTOL)){
*convergedFlag_dev = 0;
}*/
//Write the two values back!
xx[thid] = lambda_T1;
tt[thid] = 0.0;
xx[thid+1] = lambda_T2;
tt[thid+1] = 0.0;
}
// all threads not on the diagonal fall into this sync!
__syncthreads();
T_dev_ptr = PtrColOffset_ColM(T_dev_ptr,1,T_dev.outerStrideBytes);
__syncthreads();
if(thid < m){
tt[thid] += T_dev_ptr[thid] * xx[j_t+1];
}
__syncthreads();
T_dev_ptr = PtrColOffset_ColM(T_dev_ptr,1,T_dev.outerStrideBytes);
__syncthreads();
if(thid < m){
tt[thid] += T_dev_ptr[thid] * xx[j_t+2];
}
// ====================================================================================
__syncthreads();
// move T_dev_ptr 1 column
T_dev_ptr = PtrColOffset_ColM(T_dev_ptr,1,T_dev.outerStrideBytes);
// move mu_ptr to nex contact
__syncthreads();
mu_dev_ptr = &mu_dev_ptr[1];
__syncthreads();
}
__syncthreads();
// Write back the results, dont need to syncronize because
// do it anyway to be safe for testing first!
if(thid < m){
y_dev.data[ii] = xx[thid]; THIS IS UPDATED IN KERNEL B
t_dev.data[ii] = tt[thid]; THIS IS UPDATED IN KERNEL B
}
//__threadfence(); /// THIS STUPID THREADFENCE MAKES IT WORKING!
模板
__全局线程\uuuuuuuuuuuuuuuu1有序线程\uuStepa\u内核(
utilCuda::Matrix mu_dev,
utilCuda::Matrix y_dev,
utilCuda::Matrix T_dev,
utilCuda::矩阵x_old_dev,
utilCuda::Matrix d_dev,
utilCuda::Matrix t_dev,
int-kernelAIdx,
int MAXN联系人,
bool*聚合滞后(dev),
预抽,预抽){
//__threadfence()在这里或末端;然后它就可以工作了???为什么
//假设1个块,每个块的线程数和列主矩阵T\u dev
int thid=threadIdx.x;
int m=min(maxNContacts*PROX\u PACKAGE\u SIZE,BLOCK\u DIM);//这是对角块的实际大小!
int i=内核aidx*块尺寸;
int ii=i+thid;
//共享中的第一份x_old_dev
__shared_uuu PREC xx[BLOCK_DIM];//如果每个线程在限制内,则每个线程写入一个元素!!
__共享预处理tt[块尺寸];
if(thid
我将最后的解决方案与CPU进行比较,在这里,我将同步线程放在所有我能放的地方,只是为了安全,首先!(这段代码做了gauss seidel的东西)
但是,如果没有结尾或开头的线栅栏,它根本就不起作用,因为它没有意义
很抱歉有这么多的代码,但也许你可以猜到问题出在哪里,因为我已经有点力不从心了,请解释为什么会发生这种情况?
我们多次检查算法,没有内存错误(Nsight报告)或错误
其他东西,一切正常…内核A只启动一个块!如果启动连续的i
template<typename PREC, int THREADS_PER_BLOCK, int BLOCK_DIM, int PROX_PACKAGES, typename TConvexSet>
__global__ void sorProxContactOrdered_1threads_StepA_kernel(
utilCuda::Matrix<PREC> mu_dev,
utilCuda::Matrix<PREC> y_dev,
utilCuda::Matrix<PREC> T_dev,
utilCuda::Matrix<PREC> x_old_dev,
utilCuda::Matrix<PREC> d_dev,
utilCuda::Matrix<PREC> t_dev,
int kernelAIdx,
int maxNContacts,
bool * convergedFlag_dev,
PREC _absTOL, PREC _relTOL){
//__threadfence() HERE OR AT THE END; THEN IT WORKS???? WHY
// Assumend 1 Block, with THREADS_PER_BLOCK Threads and Column Major Matrix T_dev
int thid = threadIdx.x;
int m = min(maxNContacts*PROX_PACKAGE_SIZE, BLOCK_DIM); // this is the actual size of the diagonal block!
int i = kernelAIdx * BLOCK_DIM;
int ii = i + thid;
//First copy x_old_dev in shared
__shared__ PREC xx[BLOCK_DIM]; // each thread writes one element, if its in the limit!!
__shared__ PREC tt[BLOCK_DIM];
if(thid < m){
xx[thid] = x_old_dev.data[ii];
tt[thid] = t_dev.data[ii];
}
__syncthreads();
PREC absTOL = _absTOL;
PREC relTOL = _relTOL;
int jj;
//PREC T_iijj;
//Offset the T_dev_ptr to the start of the Block
PREC * T_dev_ptr = PtrElem_ColM(T_dev,i,i);
PREC * mu_dev_ptr = &mu_dev.data[PROX_PACKAGES*kernelAIdx];
__syncthreads();
for(int j_t = 0; j_t < m ; j_t+=PROX_PACKAGE_SIZE){
//Select the number of threads we need!
// Here we process one [m x PROX_PACKAGE_SIZE] Block
// First Normal Direction ==========================================================
jj = i + j_t;
__syncthreads();
if( ii == jj ){ // select thread on the diagonal ...
PREC x_new_n = (d_dev.data[ii] + tt[thid]);
//Prox Normal!
if(x_new_n <= 0.0){
x_new_n = 0.0;
}
/* if( !checkConverged(x_new,xx[thid],absTOL,relTOL)){
*convergedFlag_dev = 0;
}*/
xx[thid] = x_new_n;
tt[thid] = 0.0;
}
// all threads not on the diagonal fall into this sync!
__syncthreads();
// Select only m threads!
if(thid < m){
tt[thid] += T_dev_ptr[thid] * xx[j_t];
}
// ====================================================================================
// wee need to syncronize here because one threads finished lambda_t2 with shared mem tt, which is updated from another thread!
__syncthreads();
// Second Tangential Direction ==========================================================
jj++;
__syncthreads();
if( ii == jj ){ // select thread on diagonal, one thread finishs T1 and T2 directions.
// Prox tangential
PREC lambda_T1 = (d_dev.data[ii] + tt[thid]);
PREC lambda_T2 = (d_dev.data[ii+1] + tt[thid+1]);
PREC radius = (*mu_dev_ptr) * xx[thid-1];
PREC absvalue = sqrt(lambda_T1*lambda_T1 + lambda_T2*lambda_T2);
if(absvalue > radius){
lambda_T1 = (lambda_T1 * radius ) / absvalue;
lambda_T2 = (lambda_T2 * radius ) / absvalue;
}
/*if( !checkConverged(lambda_T1,xx[thid],absTOL,relTOL)){
*convergedFlag_dev = 0;
}
if( !checkConverged(lambda_T2,xx[thid+1],absTOL,relTOL)){
*convergedFlag_dev = 0;
}*/
//Write the two values back!
xx[thid] = lambda_T1;
tt[thid] = 0.0;
xx[thid+1] = lambda_T2;
tt[thid+1] = 0.0;
}
// all threads not on the diagonal fall into this sync!
__syncthreads();
T_dev_ptr = PtrColOffset_ColM(T_dev_ptr,1,T_dev.outerStrideBytes);
__syncthreads();
if(thid < m){
tt[thid] += T_dev_ptr[thid] * xx[j_t+1];
}
__syncthreads();
T_dev_ptr = PtrColOffset_ColM(T_dev_ptr,1,T_dev.outerStrideBytes);
__syncthreads();
if(thid < m){
tt[thid] += T_dev_ptr[thid] * xx[j_t+2];
}
// ====================================================================================
__syncthreads();
// move T_dev_ptr 1 column
T_dev_ptr = PtrColOffset_ColM(T_dev_ptr,1,T_dev.outerStrideBytes);
// move mu_ptr to nex contact
__syncthreads();
mu_dev_ptr = &mu_dev_ptr[1];
__syncthreads();
}
__syncthreads();
// Write back the results, dont need to syncronize because
// do it anyway to be safe for testing first!
if(thid < m){
y_dev.data[ii] = xx[thid]; THIS IS UPDATED IN KERNEL B
t_dev.data[ii] = tt[thid]; THIS IS UPDATED IN KERNEL B
}
//__threadfence(); /// THIS STUPID THREADFENCE MAKES IT WORKING!