Re: Defining block size during runtime

From: Gary Funck (gary_at_intrepid_dot_com)
Date: Wed Jul 22 2009 - 22:19:13 PDT

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    On 07/23/09 02:00:02, sainath l wrote:
    >    I am very much interested in knowing any workaround, if possible, for
    >    dynamically allocating an array with variable block size at runtime.
    >    Lets say I want to know if it is possible to create the following array
    >    dynamically where N and M are some variables. If yes then how can we do
    >    it.
    >    shared [M] int A[N][M];
    I'm not sure if this is what you're asking about, but attached is
    a program that uses a "trick" to ensure that each row of the array
    has affinity to a single thread, in a thread-cyclic fashion.
    The trick is that by placing the row vector 'y' inside of
    struct, we ensure that y is allocated contiguously on a
    given thread.  And for each a[i+1] (based upon UPC's
    indexing rules) we know that it will be allocated on
    the next thread (in cyclic order) after thread 'i'.
    $ upc alloc_row_struct.upc -o alloc_row_struct
    $ alloc_row_struct -n 4 4 5
    threadof a[0].y[0] = 0
    threadof a[0].y[1] = 0
    threadof a[0].y[2] = 0
    threadof a[0].y[3] = 0
    threadof a[0].y[4] = 0
    threadof a[1].y[0] = 1
    threadof a[1].y[1] = 1
    threadof a[1].y[2] = 1
    threadof a[1].y[3] = 1
    threadof a[1].y[4] = 1
    threadof a[2].y[0] = 2
    threadof a[2].y[1] = 2
    threadof a[2].y[2] = 2
    threadof a[2].y[3] = 2
    threadof a[2].y[4] = 2
    threadof a[3].y[0] = 3
    threadof a[3].y[1] = 3
    threadof a[3].y[2] = 3
    threadof a[3].y[3] = 3
    threadof a[3].y[4] = 3
    Above '-n 4' indicates that the program will run on 4 threads.
    That number was chosen to agree with the value of N (also 4)
    given above, but in fact could be any number.
    Whether this is the best method, or even a recommended practice,
    for accomplishing your objective, I'm not sure.  Perhaps others
    on the list can offer some comment or suggest alternative
    - Gary

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