Hello, what is Threshold constant in code for? I wanted to try your code,
but with Threshold 1 it take all of 16GB RAM I have and crash on sigkill.
When I use Threshold 8 it seems ok, but when I use 64, it again take a lot
of RAM... I thought it's count of Threads that program will use, while
running on CPU. But it does give unexpected or strange results.
Dátum: štvrtok 14. apríla 2011, čas: 14:55:09 UTC+2, odosielateľ: Dmitry
Vyukov
> Hi,
>
> I want to create a parallel matrix multiplication benchmark for Go. I used
> to fork-join style parallelism, so I implemented it as follows:
>
> type Matrix [][]float64
>
> func matrix_make(n int) Matrix {
> M := make([][]float64, n);
> for i := 0; i != n; i += 1 {
> M[i] = make([]float64, n)
> }
> return M
> }
>
> const (Threshold = 8)
>
> func matmult_pimpl (sync chan int, A Matrix, B Matrix, C Matrix, i0 int,
> i1 int, j0 int, j1 int, k0 int, k1 int) {
> di := i1 - i0
> dj := j1 - j0
> dk := k1 - k0
> if (di >= dj && di >= dk && di >= Threshold) {
> mi := i0 + di / 2
> sync0 := make(chan int, 1)
> go matmult_pimpl(sync0, A, B, C, i0, mi, j0, j1, k0, k1)
> matmult_pimpl(nil, A, B, C, mi, i1, j0, j1, k0, k1)
> <- sync0
> } else if (dj >= dk && dj >= Threshold) {
> mj := j0 + dj / 2
> sync0 := make(chan int, 1)
> go matmult_pimpl(sync0, A, B, C, i0, i1, j0, mj, k0, k1)
> matmult_pimpl(nil, A, B, C, i0, i1, mj, j1, k0, k1)
> <- sync0
> } else if (dk >= Threshold) {
> mk := k0 + dk / 2
> matmult_pimpl(nil, A, B, C, i0, i1, j0, j1, k0, mk)
> matmult_pimpl(nil, A, B, C, i0, i1, j0, j1, mk, k1)
> } else {
> for i := i0; i < i1; i += 1 {
> for j := j0; j < j1; j += 1 {
> for k := k0; k < k1; k += 1 {
> C[i][j] += A[i][k] * B[k][j];
> }
> }
> }
> }
> if sync != nil {
> sync <- 0
> }
> }
>
> func matmult_parallel(A Matrix, B Matrix) Matrix {
> n := len(A)
> C := matrix_make(n)
> matmult_pimpl(nil, A, B, C, 0, n, 0, n, 0, n)
> return C
> }
>
> Is it a good implementation for Go? Is it enough "Go-ish"? What would be a
> "canonical" way?
> TIA
>
>
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