// This function gets the last accelerator that
// was PR'ed on this particular slave
Huint get_last_accelerator(Huint slave_num) {
if (!check_valid_slave_num(slave_num)){
#ifdef DEBUG_DISPATCH
printf("ERROR (get_last_accelerator)!\n");
#endif
while(1);
}
return _hwti_get_last_accelerator((Huint)hwti_array[slave_num]);
}
// -------------------------------------------------------------- //
// Determine if we use HW, PR if necessary //
// -------------------------------------------------------------- //
Hbool useHW(Huint accelerator_type, Huint size) {
// Grab the VHWTI base
Huint vhwti_base = 0;
getpvr(1,vhwti_base);
// Get currently loaded accelerator
Huint current_accelerator = _hwti_get_last_accelerator(vhwti_base);
// Determine whether this slave has PR
Hbool has_PR = (Huint) _hwti_get_PR_flag(vhwti_base);
// Immediately return 0 if slave has no PR, and has no
// access to the specified "accelerator_type"
if (has_PR != PR_FLAG) {
if(current_accelerator != accelerator_type)
return 0;
}
// Update the first used accelerator (slaves init this to NO_ACC)
if (_hwti_get_first_accelerator(vhwti_base) == NO_ACC)
_hwti_set_first_accelerator(vhwti_base, accelerator_type);
// if the loaded accelerator matches the specified accelerator, return 1
// Hardware is always faster given the accelerators we currently have
if (current_accelerator == accelerator_type) {
return 1;
}
#ifdef PR
// Does this processor have PR capabilities?
if (has_PR) {
// Get tuning table pointer.
tuning_table_t (*tuning_table)[NUM_ACCELERATORS][(BRAM_SIZE/BRAM_GRANULARITY_SIZE)] = (void *) _hwti_get_tuning_table_ptr(vhwti_base);
// Get Hardware execution time for this size
unsigned char slave_num;
getpvr(0, slave_num);
float hw_time, sw_time;
if (accelerator_type != MATRIXMUL) {
hw_time = tuning_table[slave_num][accelerator_type][size/BRAM_GRANULARITY_SIZE].hw_time;
sw_time = tuning_table[slave_num][accelerator_type][size/BRAM_GRANULARITY_SIZE].sw_time;
}
else {
// Matrix Multiplication entries are insertted in a different way than others
hw_time = tuning_table[slave_num][accelerator_type][size].hw_time;
sw_time = tuning_table[slave_num][accelerator_type][size].sw_time;
}
// Calculate if PR is worth it by indexing appropriately
// into the table and evaluating the software and hardware
// execution times, taking into account PR overhead.
if ((hw_time + PR_OVERHEAD + HW_SW_THRESHOLD) < sw_time) {
// ----Begin loading the accelerator----//
// If performing PR failed, fallback to software
// execution. So return false.
// Perform PR (which updates last used accelerator)
if (perform_PR(slave_num, accelerator_type) != SUCCESS) {
return 0;
}
// Increment PR counter
Huint pr_counter = _hwti_get_accelerator_pr_counter( vhwti_base );
_hwti_set_accelerator_pr_counter( vhwti_base, ++pr_counter);
// Return immediately indicating to use HW/accelerator
return 1;
}
else
return 0;
}
#endif
// As a default, always return 0
// indicating to run in software.
return 0;
}
