[mvapich-discuss] MVAPICH on multi-GPU causes Segmentation fault
Rustico, Eugenio
eugenio.rustico at baw.de
Thu May 28 12:12:19 EDT 2015
Hi,
I think that's a very interesting idea. However, since you could in theory
access the memory of the other devices but not launch kernels on them without a
context, you should anyway use other processes to perform the computation on
them. So what would be the advantage?
Regards
Eugenio Rustico
> khaled hamidouche <hamidouc at cse.ohio-state.edu> hat am 28. Mai 2015 um 16:08
> geschrieben:
>
>
> Hi,
>
> We have not experimented with this approach. Please try it and let us know
> whether it works or not
>
> Thanks
>
> On Wed, May 27, 2015 at 10:49 PM, Yutian Li <lyt at megvii.com> wrote:
>
> > 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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