private static void ReplacementPolicyUpdate(Event aEvent)
{
// increase the lru value of all tags held in the MMU
for (int j = 0; j < MAX_TAG_VALUE; j++)
{
if (memoryManagementUnit[j].citizen)
{
memoryManagementUnit[j].lruValue++;
}
}
// set the lru value of the tag we just hit to 0
memoryManagementUnit[aEvent._trDataTags].lruValue = 0;
}
//Prints event info
private static void PrintMsg(string state, Event aEvent)
{
Console.WriteLine(state + (aEvent._eventId + 1) + " at tClk " + tCurrentClock +
" with plans to end at " + aEvent._tClockEnd);
}
// Parses the traffic csv file, and initializes all of the
// device events.
private static void ParseTrafficFile(string filePath)
{
TextFieldParser parser = new TextFieldParser(filePath);
parser.SetDelimiters(",");
// Skip over header line.
parser.ReadLine();
int i = 0;
while (!parser.EndOfData)
{
string[] fields = parser.ReadFields();
// allocate the memory for the event and add it to the list.
Event eventToAdd = new Event(
ulong.Parse(fields[(int)FieldTypes.TIME]),
fields[(int)FieldTypes.OPERATION],
int.Parse(fields[(int)FieldTypes.DEVICE]),
int.Parse(fields[(int)FieldTypes.TS]),
int.Parse(fields[(int)FieldTypes.TR_DATA_TAG]),
i
);
_listOfEvents.Add(eventToAdd);
i++;
}
numEvents = i;
}
// ************** GET DATA FROM DATA CENTER ***************
// Starts a sat downlink event to grab a tag from the data center.
private static ulong GetFromDataCenter(Event aEvent)
{
ulong additionalLatency = 0;
Event pullDown = new Event(
tCurrentClock,
"REQUEST",
SATELLITE_UPLINK_ID, // because we add 4 to requests in the main loop
aEvent._transactionSize,
aEvent._trDataTags,
++numEvents
);
_listOfEvents.Add(pullDown);
devices[SATELLITE_DOWNLINK_ID].linkOccupiedBy = numEvents;
additionalLatency = devices[SATELLITE_DOWNLINK_ID].CalculateLatency(aEvent._transactionSize);
pullDown._tClockEnd = tCurrentClock + additionalLatency;
PrintMsg("Pulling from Datacenter ", pullDown);
return additionalLatency;
}
// ****************** EVICT A TAG FROM MEMORY *****************
private static ulong Evict(int ts)
{
ulong additionalLatency;
// memory is full, satellite uplink is available, start evicting
int tagToEvict = ExecuteReplacementPolicy(ts);
// start an event to transfer the memory out to the data center
// using the satellite hub
Event eviction = new Event(
tCurrentClock,
"SEND",
SATELLITE_UPLINK_ID,
memoryManagementUnit[tagToEvict].size,
tagToEvict,
++numEvents
);
// once the eviction has started, the block is no longer valid.
// but we must wait until the eviction event is finished before
memoryManagementUnit[tagToEvict].citizen = false;
memoryManagementUnit[tagToEvict].tClkFinish = 0;
_listOfEvents.Add(eviction);
devices[SATELLITE_UPLINK_ID].linkOccupiedBy = numEvents;
additionalLatency = devices[SATELLITE_UPLINK_ID].CalculateLatency(memoryManagementUnit[tagToEvict].size);
eviction._tClockEnd = tCurrentClock + additionalLatency;
PrintMsg("Eviction ", eviction);
return additionalLatency;
}
// ************* MEMORYALLOCATE **************
// Check if we can allocate memory for the queued transaction
// Returns true if we can, otherwise returns false
// Takes in additional latency by reference and will
// add any additional latencies the allocation results in
// (for example, if we evict memory to make room, the latency of the
// of the eviction process will be added to additionalLatency)
//
private static bool AllocateMemory(Event aEvent, int maxTotalMemory, ref ulong additionalLatency)
{
//additionalLatency = 0;
bool success = false;
// if the event is a send
if (aEvent._operation == "SEND")
{
// check if we have available memory
if (maxTotalMemory - allocatedMemory >= aEvent._transactionSize)
{
allocatedMemory += aEvent._transactionSize;
success = true;
}
else if (devices[SATELLITE_UPLINK_ID].linkOccupiedBy == -1)
{
// No room, but the sat uplink is available
additionalLatency += Evict(aEvent._transactionSize);
success = true;
}
// memory is full, satellite uplink is unavailable, stall device
//PrintMsg("Stall SEND device, Mem full, sat busy ", aEvent);
}
else
{
// if the event is a request
// check if the tag is in our memory
if(memoryManagementUnit[aEvent._trDataTags].citizen)
{
// it is, we are successful
if (memoryManagementUnit[aEvent._trDataTags].tClkFinish <= tCurrentClock)
{
success = true;
}
}
else if (devices[SATELLITE_DOWNLINK_ID].linkOccupiedBy == -1 && !memoryManagementUnit[aEvent._trDataTags].incoming)
{
// If the data is not coming from a device later, we can get it from the data center
// as well as if we have memory to recieve it
if(maxTotalMemory - allocatedMemory >= aEvent._transactionSize)
{
// wonderful, we have space, we can first get it from the satellite.
additionalLatency += GetFromDataCenter(aEvent);
success = true;
}
else if (devices[SATELLITE_UPLINK_ID].linkOccupiedBy == -1)
{
// ungh... this is where things get complicat
// We need to evict things to make room for what we want from the data center.
// The uplink is free, so we can go ahead and do that, allowing us to request
// the data from the satellite.
// Having this in here makes me think there is still a logically simplier way.
additionalLatency += Evict(aEvent._transactionSize);
additionalLatency += GetFromDataCenter(aEvent);
success = true;
}
// PrintMsg("Stall REQUEST device, Mem full, sat busy ", aEvent);
// Both satellite links are busy.
// Memory is full.
// Stall initiating transfer
// success is still false from initialzation.
}
}
return success;
}
