parallel-processing

问题 There is no atomic minimal operation in OpenMP, also no intrinsic in Intel MIC's instruction set. #pragmma omp critial is very insufficient in the performance. I want to know if there is a high performance implement of atomic minimal for Intel MIC. 回答1: According to the OpenMP 4.0 Specifications (Section 2.12.6), there is a lot of fast atomic minimal operations you can do by using the #pragma omp atomic construct in place of #pragma omp critical (and thereby avoid the huge overhead of its

问题 In my MPI program, I want to send and receive information to adjacent processes. But if a process ends and doesn't send anything, its neighbors will wait forever. How can I resolve this issue? Here is what I am trying to do: if (rank == 0) { // don't do anything until all slaves are done } else { while (condition) { // send info to rank-1 and rank+1 // if can receive info from rank-1, receive it, store received info locally // if cannot receive info from rank-1, use locally stored info // do

问题 Say, i have 8 processes. When i do the following, the MPU_COMM_WORLD communicator will be splitted into two communicators. The processes with even ids will belong to one communicator and the processes with odd ids will belong to another communicator. color=myid % 2; MPI_Comm_split(MPI_COMM_WORLD,color,myid,&NEW_COMM); MPI_Comm_rank( NEW_COMM, &new_id); My question is where is the handle for these two communicators. After the split the ids of processors which before were 0 1 2 3 4 5 6 7 will

问题 I have to send and receive (MPI) a chunk of a multi-dimensional array in FORTRAN 90. The line MPI_Send(x(2:5,6:8,1),12,MPI_Real,....) is not supposed to be used, as per the book "Using MPI..." by Gropp, Lusk, and Skjellum. What is the best way to do this? Do I have to create a temporary array and send it or use MPI_Type_Create_Subarray or something like that? 回答1: The reason not to use array sections with MPI_SEND is that the compiler has to create a temporary copy with some MPI

问题 My question centers on some Parallel.ForEach code that used to work without fail, and now that our database has grown to 5 times as large, it breaks almost regularly. Parallel.ForEach<Stock_ListAllResult>( lbStockList.SelectedItems.Cast<Stock_ListAllResult>(), SelectedStock => { ComputeTipDown( SelectedStock.Symbol ); } ); The ComputeTipDown() method gets all daily stock tic data for the symbol, and iterates through each day, gets yesterday's data and does a few calculations and then inserts

问题 I have seven licenses of a particular software. Therefore, I want to start 7 jobs simultaneously. I can do that using '&'. Now, 'wait' command waits till the end of all of those 7 processes to be finished to spawn the next 7. Now, I would like to write the shell script where after I start the first seven, as and when a job gets completed I would like to start another. This is because some of those 7 jobs might take very long while some others get over really quickly. I don't want to waste

问题 I'm trying to calculate the number of transitions that would be made in a run of Conway's GOL for a pxq matrix for n iterations. For instance, given 1 iteration with the initial state being 1 blinker (as below). there would be 5 transitions (2 births, 1 survival, 2 deaths from underpopulation). I've already got this working, but I'd like to convert this logic to run using CUDA. Below is what I want to port to CUDA. code: static void gol() // call this iterations x's { int[] tempGrid = new int

问题 I am using Parallel function from joblib package in Python. I would like to use this function only for handle one of my functions but unfortunately the whole code is running in parallel (apart from other functions). Example: from joblib import Parallel, delayed print ('I do not want this to be printed n times') def do_something(arg): some calculations(arg) Parallel(n_jobs=5)(delayed(do_something)(i) for i in range(0, n)) 回答1: This is a common error to miss a design direction from

问题 I wish to run random forest in parallel using caret package, and I wish to set the seeds for reproducible result as in Fully reproducible parallel models using caret. However, I don't understand line 9 in the following code taken from caret help: why do we sample 22 (plus the last model in line 12, 23) integer numbers (12 values for parameter k are evaluated)? For information, I wish to run 5-fold CV to evaluate 584 values for RF parameter 'mtry'. Any help is much appreciated. Thank you. ##

问题 I wish to run random forest in parallel using caret package, and I wish to set the seeds for reproducible result as in Fully reproducible parallel models using caret. However, I don't understand line 9 in the following code taken from caret help: why do we sample 22 (plus the last model in line 12, 23) integer numbers (12 values for parameter k are evaluated)? For information, I wish to run 5-fold CV to evaluate 584 values for RF parameter 'mtry'. Any help is much appreciated. Thank you. ##