13 Replies Latest reply on Sep 28, 2010 2:34 PM by himanshu.gautam

    why only one GPU is working

    ThomasUCF
      four GPU installed correctly,only one working

         Hi all, I installed two HD 5970s in my computer, that is equal to four HD5870s. When I run the Nbody simulation in the ATI stream sample, only one is working. How can I make them work together? 

         Thanks a lot!

        • why only one GPU is working
          himanshu.gautam

          ThomasUCF,

          In SDK version 2.2 only a few samples run on all available GPUs including SimpleMultiDevice,MandelBrot. All other samples run by default on the 0th device. 

          In version 2.3 you will have the option of choosing the gpu(on which you want to run the sample) in multigpu systems.

          I hope the doubt is cleared.

            • why only one GPU is working
              ThomasUCF

               Thank you so much, it's a great help.

               Here I have another, when I change all device[0] in the sample code  to device[1], it's not working right. Do you have any ideas?

                • why only one GPU is working
                  himanshu.gautam

                  ThomasUCF,

                  Send a test case.

                    • why only one GPU is working
                      ThomasUCF

                       Hi Himanshu:

                      For example, the Nbody problem, when I change device[0] in the sample code to device[1], I can nolonger see all the particles moving, I can only see one particle in the center.

                       Any explanations on this?

                       

                       Thanks a lot.

                      Thomas

                        • why only one GPU is working
                          nou

                          this may be bug related to that second core of 5970 return garbage results. do you have windows? on linux there are posibility that 5970 working correctly.

                            • why only one GPU is working
                              himanshu.gautam

                              Please post the output of SimpleMultiDevice sample.

                                • why only one GPU is working
                                  ThomasUCF

                                  ----------------------------------------------------------
                                  CPU + GPU Test 1 : Single context Single Thread
                                  ----------------------------------------------------------
                                  Total time : 59.0422
                                  Time of CPU : 54.4086
                                  Time of GPU : 5.24897
                                  ----------------------------------------------------------
                                  CPU + GPU Test 2 : Multiple context Single Thread
                                  ----------------------------------------------------------
                                  Total time : 59.0422
                                  Time of CPU : 56.7377
                                  Time of GPU : 2.00775
                                  ----------------------------------------------------------
                                  CPU + GPU Test 3 : Multiple context Multiple Thread
                                  ----------------------------------------------------------
                                  Total time : 59.7269
                                  Time of CPU : 59.2351
                                  Time of GPU : 2.00951
                                  ----------------------------------------------------------
                                  Multi GPU Test 1 : Single context Single Thread
                                  ----------------------------------------------------------
                                  Total time : 41.9174
                                  Time of GPU0 : 4.61716
                                  Time of GPU1 : 3.12945
                                  Time of GPU2 : 3.16599
                                  Time of GPU3 : 2.01411
                                  ----------------------------------------------------------
                                  Multi GPU Test 2 : Multiple context Single Thread
                                  ----------------------------------------------------------
                                  Total time : 39.2678
                                  Time of GPU0 : 4.6637
                                  Time of GPU1 : 3.12808
                                  Time of GPU2 : 3.13052
                                  Time of GPU3 : 3.15125
                                  ----------------------------------------------------------
                                  Multi GPU Test 3 : Multiple context Multiple Thread
                                  ----------------------------------------------------------
                                  Total time : 40.339
                                  Time of GPU0 : 4.57501
                                  Time of GPU1 : 3.20865
                                  Time of GPU2 : 3.12312
                                  Time of GPU3 : 3.17568
                                  Press any key to continue . . .

                                  Above is the test result for SimpleMultiDevice.

                                  My main concern is to use all four GPUs for computing, now I  simply change the "device[0]" to "device[1]" to see if this works. It turns out not working. So here is my question:

                                  1): Is there any driver to combine the four GPUs to make them act as a more powerful one?

                                  2): If not, can you point a way how I should harness them to imporve the computation power?

                                   Thanks again, I really appreciate it.

                                  Thomas

                                    • why only one GPU is working
                                      himanshu.gautam

                                      ThomasUCF,

                                      Please run the sample SimpleMultiDevice with -e option. If you get a Pass Message for every GPU,then all your GPUs are working properly.In that case you can definitely use them.

                                        • why only one GPU is working
                                          ThomasUCF

                                          Hi Humanshu:

                                           

                                            yeah,it says passed. Thanks a lot.

                                          Thomas

                                            • why only one GPU is working
                                              n0thing

                                              SDK 2.2 Developer release notes -

                                               

                                              The ATI Radeon™ HD 5970 GPU is currently supported in single-GPU mode only. It is recommended users only access the first device on an ATI Radeon™ HD 5970 GPU for GPU compute.



                                                • why only one GPU is working
                                                  sergey_ilich

                                                  When I can work on second GPU on 5970 ?

                                                  I saw test with options  there is veryfying results on gpu0-gpu3, and you say that it is working only device[0]

                                                  ----------------------------------------------------------
                                                  CPU + GPU Test 1 : Single context Single Thread
                                                  ----------------------------------------------------------
                                                  Total time : 63.9546
                                                  Time of CPU : 59.64
                                                  Time of GPU : 3.22437
                                                  Verifying results for CPU : Passed!
                                                  Verifying results for GPU : Passed!
                                                  ----------------------------------------------------------
                                                  CPU + GPU Test 2 : Multiple context Single Thread
                                                  ----------------------------------------------------------
                                                  Total time : 63.9546
                                                  Time of CPU : 53.0936
                                                  Time of GPU : 3.08569
                                                  Verifying results for CPU : Passed!
                                                  Verifying results for GPU : Passed!
                                                  ----------------------------------------------------------
                                                  CPU + GPU Test 3 : Multiple context Multiple Thread
                                                  ----------------------------------------------------------
                                                  Total time : 51.6011
                                                  Time of CPU : 49.377
                                                  Time of GPU : 3.06322
                                                  Verifying results for CPU : Passed!
                                                  Verifying results for GPU : Passed!
                                                  ----------------------------------------------------------
                                                  Multi GPU Test 1 : Single context Single Thread
                                                  ----------------------------------------------------------
                                                  Total time : 27.2769
                                                  Time of GPU0 : 3.04458
                                                  Time of GPU1 : 2.94096
                                                  Time of GPU2 : 3.07542
                                                  Time of GPU3 : 3.07895
                                                  Verifying results for GPU0 : Passed!
                                                  Verifying results for GPU1 : Passed!
                                                  Verifying results for GPU2 : Passed!
                                                  Verifying results for GPU3 : Passed!
                                                  ----------------------------------------------------------
                                                  Multi GPU Test 2 : Multiple context Single Thread
                                                  ----------------------------------------------------------
                                                  Total time : 30.2896
                                                  Time of GPU0 : 3.07658
                                                  Time of GPU1 : 2.91558
                                                  Time of GPU2 : 3.01686
                                                  Time of GPU3 : 3.05854
                                                  Verifying results for GPU0 : Passed!
                                                  Verifying results for GPU1 : Passed!
                                                  Verifying results for GPU2 : Passed!
                                                  Verifying results for GPU3 : Passed!
                                                  ----------------------------------------------------------
                                                  Multi GPU Test 3 : Multiple context Multiple Thread
                                                  ----------------------------------------------------------
                                                  Total time : 30.5671
                                                  Time of GPU0 : 3.05937
                                                  Time of GPU1 : 3.04916
                                                  Time of GPU2 : 3.02367
                                                  Time of GPU3 : 3.18991
                                                  Verifying results for GPU0 : Passed!
                                                  Verifying results for GPU1 : Passed!
                                                  Verifying results for GPU2 : Passed!
                                                  Verifying results for GPU3 : Passed!

                                        • why only one GPU is working
                                          ThomasUCF

                                           Thanks, yes I am using windows 7. I have two 5970s, so I have device[0],device[1],device[2],device[3], but only device[0] give the right result. Can you explain that?

                                           Thanks again.