[mvapich-discuss] MVAPICH on multi-GPU causes Segmentation fault
Yutian Li
lyt at megvii.com
Wed May 27 22:49:27 EDT 2015
Thanks.
Can I use one GPU as my "proxy GPU", accessing memory of all other GPUs
through this one using UVA. Like when I'm sending GPU1's data out, I first
set device to GPU0, then I pass the pointer to the memory in GPU1 and call
MPI_Send. Would that work?
On Wed, May 27, 2015 at 10:00 PM, khaled hamidouche <
hamidouc at cse.ohio-state.edu> wrote:
> Hi Yutian,
>
> In MVAPICH2, an MPI process cannot support multiple context (GPUs). So in
> your case you need to use multiple processes and each process using it own
> GPU.
>
> Thanks
>
> On Wed, May 27, 2015 at 1:18 AM, Yutian Li <lyt at megvii.com> wrote:
>
>> I'm using MVAPICH2 2.1 on a Debian 7 machine. It has multiple cards of
>> Tesla K40m. I am running into segmentation fault when I'm using multiple
>> GPU cards.
>> The code is as follows.
>>
>> #include <cstdio>
>> #include <cstdlib>
>> #include <ctime>
>> #include <cuda_runtime.h>
>> #include <mpi.h>
>>
>> int main(int argc, char** argv) {
>> MPI_Status status;
>> int rank;
>> MPI_Init(&argc, &argv);
>> MPI_Comm_rank(MPI_COMM_WORLD, &rank);
>> cudaSetDevice(0);
>> if (rank == 0) {
>> srand(time(0));
>> float* a;
>> float num = rand();
>> cudaMalloc(&a, sizeof(float));
>> cudaMemcpy(a, &num, sizeof(float), cudaMemcpyDefault);
>> MPI_Send(a, sizeof(float), MPI_CHAR, 1, 0, MPI_COMM_WORLD);
>> printf("sent %f\n", num);
>> } else {
>> float* a;
>> float num;
>> cudaMalloc(&a, sizeof(float));
>> MPI_Recv(a, sizeof(float), MPI_CHAR, 0, 0, MPI_COMM_WORLD,
>> &status);
>> cudaMemcpy(&num, a, sizeof(float), cudaMemcpyDefault);
>> printf("received %f\n", num);
>> }
>> cudaSetDevice(1);
>> if (rank == 0) {
>> float* a;
>> float num = rand();
>> cudaMalloc(&a, sizeof(float));
>> cudaMemcpy(a, &num, sizeof(float), cudaMemcpyDefault);
>> MPI_Send(a, sizeof(float), MPI_CHAR, 1, 0, MPI_COMM_WORLD);
>> printf("sent %f\n", num);
>> } else {
>> float* a;
>> float num;
>> cudaMalloc(&a, sizeof(float));
>> MPI_Recv(a, sizeof(float), MPI_CHAR, 0, 0, MPI_COMM_WORLD,
>> &status);
>> cudaMemcpy(&num, a, sizeof(float), cudaMemcpyDefault);
>> printf("received %f\n", num);
>> }
>> MPI_Finalize();
>> return 0;
>> }
>>
>> In short, I first set device to GPU 0, send something. Then I set device
>> to GPU 1, send something.
>>
>> The output is as follows.
>>
>> sent 1778786688.000000
>> received 1778786688.000000
>> [debian:mpi_rank_0][error_sighandler] Caught error: Segmentation
>> fault (signal 11)
>> [debian:mpispawn_0][readline] Unexpected End-Of-File on file
>> descriptor 7. MPI process died?
>> [debian:mpispawn_0][mtpmi_processops] Error while reading PMI socket.
>> MPI process died?
>> [debian:mpispawn_0][child_handler] MPI process (rank: 0, pid: 30275)
>> terminated with signal 11 -> abort job
>> [debian:mpirun_rsh][process_mpispawn_connection] mpispawn_0 from node
>> debian aborted: Error while reading a PMI socket (4)
>>
>> So the first send is OK. But as soon as I set my device to the other GPU,
>> and then MPI send, boom! I wonder why this is happening.
>>
>> Also, I built MVAPICH with the following command.
>>
>> ./configure --enable-cuda --with-cuda=/usr/local/cuda
>> --with-device=ch3:mrail --enable-rdma-cm
>>
>> I have debugging enabled and stack trace printed. Hopefully this helps..
>>
>> sent 1377447040.000000
>> received 1377447040.000000
>> [debian:mpi_rank_0][error_sighandler] Caught error: Segmentation
>> fault (signal 11)
>> [debian:mpi_rank_0][print_backtrace] 0:
>> /home/lyt/local/lib/libmpi.so.12(print_backtrace+0x1c) [0x7fba26a00b3c]
>> [debian:mpi_rank_0][print_backtrace] 1:
>> /home/lyt/local/lib/libmpi.so.12(error_sighandler+0x59) [0x7fba26a00c39]
>> [debian:mpi_rank_0][print_backtrace] 2:
>> /lib/x86_64-linux-gnu/libpthread.so.0(+0xf8d0) [0x7fba23ffe8d0]
>> [debian:mpi_rank_0][print_backtrace] 3:
>> /usr/lib/libcuda.so.1(+0x21bb30) [0x7fba26fa9b30]
>> [debian:mpi_rank_0][print_backtrace] 4:
>> /usr/lib/libcuda.so.1(+0x1f6695) [0x7fba26f84695]
>> [debian:mpi_rank_0][print_backtrace] 5:
>> /usr/lib/libcuda.so.1(+0x205586) [0x7fba26f93586]
>> [debian:mpi_rank_0][print_backtrace] 6:
>> /usr/lib/libcuda.so.1(+0x17ad88) [0x7fba26f08d88]
>> [debian:mpi_rank_0][print_backtrace] 7:
>> /usr/lib/libcuda.so.1(cuStreamWaitEvent+0x63) [0x7fba26ed72e3]
>> [debian:mpi_rank_0][print_backtrace] 8:
>> /usr/local/cuda/lib64/libcudart.so.6.5(+0xa023) [0x7fba27cff023]
>> [debian:mpi_rank_0][print_backtrace] 9:
>> /usr/local/cuda/lib64/libcudart.so.6.5(cudaStreamWaitEvent+0x1ce)
>> [0x7fba27d2cf3e]
>> [debian:mpi_rank_0][print_backtrace] 10:
>> /home/lyt/local/lib/libmpi.so.12(MPIDI_CH3_CUDAIPC_Rendezvous_push+0x17f)
>> [0x7fba269f25bf]
>> [debian:mpi_rank_0][print_backtrace] 11:
>> /home/lyt/local/lib/libmpi.so.12(MPIDI_CH3_Rendezvous_push+0xe3)
>> [0x7fba269a0233]
>> [debian:mpi_rank_0][print_backtrace] 12:
>> /home/lyt/local/lib/libmpi.so.12(MPIDI_CH3I_MRAILI_Process_rndv+0xa4)
>> [0x7fba269a0334]
>> [debian:mpi_rank_0][print_backtrace] 13:
>> /home/lyt/local/lib/libmpi.so.12(MPIDI_CH3I_Progress+0x19a) [0x7fba2699aeaa]
>> [debian:mpi_rank_0][print_backtrace] 14:
>> /home/lyt/local/lib/libmpi.so.12(MPI_Send+0x6ef) [0x7fba268d118f]
>> [debian:mpi_rank_0][print_backtrace] 15: ./bin/minimal.run()
>> [0x400c15]
>> [debian:mpi_rank_0][print_backtrace] 16:
>> /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xf5) [0x7fba23c67b45]
>> [debian:mpi_rank_0][print_backtrace] 17: ./bin/minimal.run()
>> [0x400c5c]
>> [debian:mpispawn_0][readline] Unexpected End-Of-File on file
>> descriptor 6. MPI process died?
>> [debian:mpispawn_0][mtpmi_processops] Error while reading PMI socket.
>> MPI process died?
>> [debian:mpispawn_0][child_handler] MPI process (rank: 0, pid: 355)
>> terminated with signal 11 -> abort job
>> [debian:mpirun_rsh][process_mpispawn_connection] mpispawn_0 from node
>> debian8 aborted: Error while reading a PMI socket (4)
>>
>> PS: I also uploaded the same question on Stack Overflow (
>> http://stackoverflow.com/questions/30455846/mvapich-on-multi-gpu-causes-segmentation-fault).
>> Refer to this link if you want more syntax highlighting.
>>
>> Thanks!
>>
>>
>> _______________________________________________
>> mvapich-discuss mailing list
>> mvapich-discuss at cse.ohio-state.edu
>> http://mailman.cse.ohio-state.edu/mailman/listinfo/mvapich-discuss
>>
>>
>
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