Hardware not working as intended

Hi all,

I am stuck with a problem since many days and I am unable to debug.

Any help is appreciated.

I have a OpenCL FPGA kernel which is a part of larger program.

it has something like

if(tid <numVertices{

do-some floating point ops

}

In the host code i want to call the function in a loop after setting arguments;

for(int i=0;i<100;i++){

// some operations

err = clEnqueueNDRangeKernel(command_queue, kernel[3], 1, NULL,

workSize_4, localWorkSize_4, 0, NULL, &clContext.events[1]);

clFinish(command_queue);

ExitError(checkErr(err, "Failed to execute kernel4!"));

//some more operations

}

---------------

Everything works fine (as intended) in emulation and also on CPU.

The problem comes when I execute it on Altera FPGA (both Intel Harp and Nallatech) with the generated respective aocx files

When the numVertices is "even"(multiple of 2), the code exits normally and the output is as intended, but when numVertices is "odd" the process enters into sleep state and stays there forever. No error is shown.

When I try to debug using GDB, SIG INT 44 is shown. I tried to use pstack but was not able to find the exact problem.

Thank you.

Regards,

Sharat

The kernel (not yest optimized) which fails to execute is as shown below:

----------------------------# define KNOB_COMPUTE_UNITS_1 1# define KNOB_SIMD_1 1# define KNOB_NUM_WORK_ITEMS_1 256

/* kernel 4*/ # ifdef ALTERA_CL

__attribute__ ((reqd_work_group_size(KNOB_NUM_WORK_ITEMS_1,1,1)))

__attribute__ ((num_simd_work_items(KNOB_SIMD_1)))

__attribute__ ((num_compute_units(KNOB_COMPUTE_UNITS_1)))# endif

__kernel void kernel4(__global double* restrict newpr,

__global double* restrict w,

unsigned int numVertices

) { //numVertices private variable

__private size_t tid = get_global_id(0);

if(tid< numVertices){

newpr[tid] += w[0] * (1/(double)numVertices);

}

}