Hi all, I'm writing an opencl kernel to find maximal cliques. The kernel
selects a node by the thread gid and finds the max subgraph containing that
node. Unfortunately, around 10000 nodes, I get an out of memory error. The
program is for one of my math professors and tests a conjecture of his, so
I can't post the code in it's entirety, but I'll give a simplified example.
I've tried cutting down the size of the static arrays in the functions that
have them. Is there anything else I can do other than get a card with more
memory?
Thanks for your time,
Tyler
#!/usr/bin/python2.7
import pyopencl as cl
import numpy
def max_clique(nodes_list, resid_list):
resid_list.append(0)
num_nodes = numpy.int32(len(nodes_list))
num_resid = numpy.int32(len(resid_list))
nodes_arr = numpy.array(nodes_list, dtype='i4')
resid_arr = numpy.array(resid_list, dtype='i4')
ctx = cl.create_some_context()
queue = cl.CommandQueue(ctx)
mf = cl.mem_flags
nodes_buf = cl.Buffer(ctx, mf.READ_ONLY | mf.COPY_HOST_PTR,
hostbuf=nodes_arr)
resid_buf = cl.Buffer(ctx, mf.READ_ONLY | mf.COPY_HOST_PTR,
hostbuf=resid_arr)
dest_buf = cl.Buffer(ctx, mf.WRITE_ONLY, nodes_arr.nbytes)
prg = cl.Program(ctx, """
bool adj(int node1, int node2, __global int *adj)
{
// are node1 and node2 adjacent?
}
// checks if node is adj to all nodes in chain
bool adj_all(int* nodes, int* G, int chain_len, int node, __global
int* adj){
// is node adjacent to to all nodes in G?
}
#define MAX_NODES 64
int chain(int num_nodes, int* nodes, __global int* connect)
{
int cur[MAX_NODES];
// Find max clique in G
}
__kernel void max_clique(__global int *nodes,
__global int *resid,
__global int *out,
int num_nodes,
int num_resid)
{
int gid = get_global_id(0);
int G[constant];
// find subgraph around nodes[gid], we call it G, store
// it's nodes in G
out[gid] = // max clique of G;
}
""").build()
prg.max_clique(queue, nodes_arr.shape, None, nodes_buf,
resid_buf,
dest_buf,
num_nodes,
num_resid)
cliques = numpy.empty_like(nodes_arr)
cl.enqueue_copy(queue, cliques, dest_buf)
return max(cliques)
print max_clique(range(0, 10000), range(1, 10))
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