mpi

问题 I've found that MPI_Probe is used to find the message size, and MPI_Get_count to find the message length. What's the difference between message length and message size? Aren't they both same? Moreover what's the count parameter in the MPI_Send or MPI_Recv signifies? Does it implies the no of times the same message will be sent/recieve from Process x to process y? 回答1: While MPI_Probe may be used to find the size of a message you have to use MPI_Get_count to get that size. MPI_Probe returns a

问题 I've found that MPI_Probe is used to find the message size, and MPI_Get_count to find the message length. What's the difference between message length and message size? Aren't they both same? Moreover what's the count parameter in the MPI_Send or MPI_Recv signifies? Does it implies the no of times the same message will be sent/recieve from Process x to process y? 回答1: While MPI_Probe may be used to find the size of a message you have to use MPI_Get_count to get that size. MPI_Probe returns a

问题 I Wrote this code in order to trace and inspect the communication in MPI model. the idea here is that, if there are for example 8 proceccors, the node-0- will communicate with itself and node-4-. also node-4- communicate with node-6- and node-2- on the other side of tree communicate with node-3-. here is the image of this scheme. so i wrote the code below to see how nodes pass an Array of elements to each other. the line 31 to 33 doese calculate the parameters of each node. just like binary

问题 Why do Merge() and Disconnect() freeze when I try to use mpi4py on CentOS 7? I'm using Python 2.7.5, mpi4py 2.0.0, and I had to load the openmpi/gnu/1.8.8 module. I had trouble doing this under CentOS 6, and the only version of MPI that worked for me was openmpi/gnu/1.6.5 . Unfortunately, I don't see that version in the yum repositories for CentOS 7. Is there a way to trace what's happening in mpi4py or MPI? Is there a way to get the older version of MPI on CentOS 7? Here's the code I'm

问题 Why do Merge() and Disconnect() freeze when I try to use mpi4py on CentOS 7? I'm using Python 2.7.5, mpi4py 2.0.0, and I had to load the openmpi/gnu/1.8.8 module. I had trouble doing this under CentOS 6, and the only version of MPI that worked for me was openmpi/gnu/1.6.5 . Unfortunately, I don't see that version in the yum repositories for CentOS 7. Is there a way to trace what's happening in mpi4py or MPI? Is there a way to get the older version of MPI on CentOS 7? Here's the code I'm

问题 if I have this code: int main(void) { int result=0; int num[6] = {1, 2, 4, 3, 7, 1}; if (my_rank != 0) { MPI_Reduce(num, &result, 6, MPI_INT, MPI_MIN, 0, MPI_COMM_WORLD); } else { MPI_Reduce(num, &result, 6, MPI_INT, MPI_MIN, 0, MPI_COMM_WORLD) printf("result = %d\n", result); } } the result print is 1 ; But if the num[0]=9 ; then the result is 9 I read to solve this problem I must to define the variable num as array. I can't understand how the function MPI_Reduce works with MPI_MIN . Why, if

问题 if I have this code: int main(void) { int result=0; int num[6] = {1, 2, 4, 3, 7, 1}; if (my_rank != 0) { MPI_Reduce(num, &result, 6, MPI_INT, MPI_MIN, 0, MPI_COMM_WORLD); } else { MPI_Reduce(num, &result, 6, MPI_INT, MPI_MIN, 0, MPI_COMM_WORLD) printf("result = %d\n", result); } } the result print is 1 ; But if the num[0]=9 ; then the result is 9 I read to solve this problem I must to define the variable num as array. I can't understand how the function MPI_Reduce works with MPI_MIN . Why, if

问题 I am trying to calculate the position of some bodies that is based in their previous positions. So in every k loop I need every C array to be updated with the new coordinates (x,y,z) of the bodies that is calculated and stored in the Cw arrays. I tried MPI_Allgather but I can't find the right syntax to achieve it. I've checked the output with the serial version of the problem for k=1 and the values of F,V and Cw arrays are right so the only problem is the MPI_Allgather. The dt variable for

问题 A seemingly silly question but I can't seem to find a definitive answer one way or the other. The basic questions is do I need to have a corresponding MPI::Irecv for an MPI::Isend? That is, even though the message sending is non-blocking, as long as I wait on the sends to complete before reusing the send buffers, do I need to use non-blocking receives & waits to receive the sent buffers? My point is, I want to use non-blocking sends to “do other stuff” while the message is being sent but the

问题 i implemented Parallel Merge sort in this code using the tree Structural scheme. but it doesn't sort the Array! could you take look at it and tell me what wrong is ? for communication among the processor i used the normal MPI_send() and MPI_recv(). however i used numbers -0- and -1- and -2- as tags for the fifth argument of MPI_recv() . for 8 processors the tree structural scheme gives the Array to the processor with rank-0- then it splits the array in half an gives the right half to