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snooping.py
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snooping.py
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from collections import defaultdict
from constants import INVALID, SHARED, SHARED_CLEAN, SHARED_MODIFIED, MODIFIED, EXCLUSIVE
class Snooping:
def __init__(self, caches):
self.caches = caches
self.shared_cache = defaultdict(set)
self.exclusive_cache = {}
self.data_traffic = 0
self.bus_updates = 0
self.invalidations = 0
self.stall_cycle = 0
self.add_caches()
def add_caches(self):
for cache in self.caches:
cache.set_common_snooping(self)
def add_shared_cache(self, block_index, core_num):
self.shared_cache[block_index].add(core_num)
self.exclusive_cache[block_index] = False if len(self.shared_cache[block_index]) > 1 else True
def remove_shared_cache(self, block_index, core_num):
if block_index in self.shared_cache:
if core_num in self.shared_cache[block_index]:
self.shared_cache[block_index].remove(core_num)
self.exclusive_cache[block_index] = False if len(self.shared_cache[block_index]) > 1 else True
if len(self.shared_cache[block_index]) == 0:
self.shared_cache.pop(block_index)
self.exclusive_cache.pop(block_index)
def is_cache_shared(self, block_index):
return (block_index in self.shared_cache)
def is_cache_exclusive(self, block_index):
return self.exclusive_cache.get(block_index, False)
#Snooping gets busy when transfering a cache block from one processor to another
def is_busy(self):
if self.stall_cycle <= 1:
self.stall_cycle = 0
return False
else:
self.stall_cycle -= 1
return True
def set_cycle_busy(self, cycles):
self.stall_cycle = cycles
def snoop_caches(self, core_num, instr_type, snoop_action, block_index, set_index, tag):
if snoop_action is None:
return
self.data_traffic += 1
is_private_access = is_public_access = False
for cache in self.caches:
if cache.core_num == core_num:
continue
cache_state = cache.snooping_next_state_transtion(instr_type, snoop_action, block_index, set_index, tag)
if cache_state == MODIFIED or cache_state == EXCLUSIVE:
is_private_access = True
elif cache_state == SHARED or cache_state == SHARED_CLEAN or cache_state == SHARED_MODIFIED:
is_public_access = True
if is_private_access:
self.caches[core_num].private_data_access += 1
if is_public_access:
self.caches[core_num].public_data_access += 1