PGI User Forum
 SearchSearch   MemberlistMemberlist     RegisterRegister   ProfileProfile    Log inLog in 

CUDA-x86.

thread private common block
Goto page 1, 2  Next
 
Post new topic   Reply to topic    PGI User Forum Forum Index -> Accelerator Programming
View previous topic :: View next topic  
Author Message
pilot117



Joined: 25 Jun 2012
Posts: 8
PostPosted: Wed Aug 08, 2012 2:32 pm    Post subject: thread private common block Reply with quote
If some common block is declared as thread private, could I use the openAcc to update the arrays defined in the common block?

I did some test, it seems that, whenever the common block is thread private, any updates by openAcc kernel will result in a runtime error:

Code:

line xxxx: cudaEventSynchronize returned status 4: unspecified launch failure


thanks
Back to top
View user's profile
mkcolg



Joined: 30 Jun 2004
Posts: 4996
Location: The Portland Group Inc.
PostPosted: Wed Aug 08, 2012 3:41 pm    Post subject: Reply with quote
Hi pilot117,

There's a couple of features not yet available. Threadprivate is one, host_data and device resident the others.

- Mat
Back to top
View user's profile
pilot117



Joined: 25 Jun 2012
Posts: 8
PostPosted: Wed Aug 08, 2012 4:08 pm    Post subject: Reply with quote
Hi, Mat, many thanks for the answer. What do you mean "host_data and device resident the others"?

Btw, could you explain the reason a little bit more?

From my understanding: for the thread private common block, each thread will have one copy. When I do something like this:

Code:

 subroutine mysub()
      integer N,i
      parameter (N=1048576)
      common/blk/t1(N),t2(N),t3(N)
c$omp threadprivate (/blk/)
!$acc kernels
!$acc loop
      do i=1,N
         t2(i)=t1(i)*t1(i)+t2(i)*t3(N)
      enddo
!$acc end kernels
      return
      end


will the openAcc see different copies of t2 or does the multiple copies cause the problem? It seems that reading t1, t2, t3 is ok. But its the writing that causes the problem. Even I only use 1 thread, I still got the same runtime error, which suggests that something mystery and deep inside the openAcc implementations. If you could explain it or direct me to some reference, that would be great!


mkcolg wrote:
Hi pilot117,

There's a couple of features not yet available. Threadprivate is one, host_data and device resident the others.

- Mat
Back to top
View user's profile
mkcolg



Joined: 30 Jun 2004
Posts: 4996
Location: The Portland Group Inc.
PostPosted: Fri Aug 10, 2012 9:08 am    Post subject: Reply with quote
Hi pilot117,

I didn't realize you we're meaning the OpenMP threadprivate. OpenACC also has a "threadprivate" directive but it's still in development.

I'm away at a conference so will ask one of our other application engineer to investigate using an OpenMP threadprivate variable within an OpenACC compute region. I've not tried it before.

- Mat
Back to top
View user's profile
pilot117



Joined: 25 Jun 2012
Posts: 8
PostPosted: Fri Aug 10, 2012 9:19 am    Post subject: Reply with quote
mkcolg wrote:
Hi pilot117,

I didn't realize you we're meaning the OpenMP threadprivate. OpenACC also has a "threadprivate" directive but it's still in development.

I'm away at a conference so will ask one of our other application engineer to investigate using an OpenMP threadprivate variable within an OpenACC compute region. I've not tried it before.

- Mat


Many thanks! Here I provide my example and compilation command in case you need a quick testing case:
Code:

      subroutine mysub()
      integer N,i
      parameter (N=1048576)
      common/blk/t1(N),t2(N),t3(N)
c$omp threadprivate (/blk/)
!$acc update device(t1,t2,t3)
!$acc kernels
!$acc loop
      do i=1,N
         t2(i)=t1(i)*t1(i)+t2(i)*t3(N)
      enddo
!$acc end kernels
!$acc update host(t2)
      return
      end

      program mainTest
      integer N,i
      parameter (N=1048576)
      real t1(1:N),t2(1:N),t3(1:N)
      common/blk/t1,t2,t3

!$acc mirror(t1,t2,t3)

      do i=1,N
         CALL RANDOM_NUMBER(HARVEST=X)
         t1(i)=X
         CALL RANDOM_NUMBER(HARVEST=X)
         t2(i)=X
         CALL RANDOM_NUMBER(HARVEST=X)
         t3(i)=X
      enddo
 

      do j=1,10
      call mysub()
      end do

      end program mainTest


the compile command:
Code:

pgf90 -o test -acc -mp -ta=nvidia:cc2.0,time -Minfo=accel -Mcuda -Mvect simpleTest.f


Here are from my output:
Code:

pilot@mars:~/Codes/test$ ./test
line 9: cudaEventSynchronize returned status 4: unspecified launch failure

Accelerator Kernel Timing data
/home/pilot/Codes/test/simpleTest.f
  mysub
    7: region entered 1 time
        time(us): init=0
                  data=12
        9: kernel launched 1 times
            grid: [8192]  block: [128]
            time(us): total=0 max=0 min=0 avg=0
/home/pilot/Codes/test/simpleTest.f
  mysub
    6: region entered 1 time
        time(us): init=0
                  data=3,441
/home/pilot/Codes/test/simpleTest.f
  maintest
    23: region entered 1 time
        time(us): init=135,083

Back to top
View user's profile
Display posts from previous:   
Post new topic   Reply to topic    PGI User Forum Forum Index -> Accelerator Programming All times are GMT - 7 Hours
Goto page 1, 2  Next
Page 1 of 2

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001, 2002 phpBB Group