* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
- * Authors: Stephan Diestelhorst <stephan.diestelhorst@arm.com>
+ * Authors: Stephan Diestelhorst
*/
/**
}
/**
- * Init a new snoop filter and tell it about all the
- * slave ports of the enclosing bus.
+ * Init a new snoop filter and tell it about all the slave ports
+ * of the enclosing bus.
*
* @param slave_ports Slave ports that the bus is attached to.
*/
* call finishRequest once it is known if the request needs to
* retry or not.
*
- * @param cpkt Pointer to the request packet. Not changed.
+ * @param cpkt Pointer to the request packet. Not changed.
* @param slave_port Slave port where the request came from.
* @return Pair of a vector of snoop target ports and lookup latency.
*/
* reqLookupResult.
*
* @param will_retry This request will retry on this bus / snoop filter
- * @param cpkt Request packet, merely for sanity checking
+ * @param cpkt Request packet, merely for sanity checking
*/
void finishRequest(bool will_retry, const Packet* cpkt);
/**
- * Handle an incoming snoop from below (the master port). These can upgrade the
- * tracking logic and may also benefit from additional steering thanks to the
- * snoop filter.
+ * Handle an incoming snoop from below (the master port). These
+ * can upgrade the tracking logic and may also benefit from
+ * additional steering thanks to the snoop filter.
+ *
* @param cpkt Pointer to const Packet containing the snoop.
* @return Pair with a vector of SlavePorts that need snooping and a lookup
* latency.
std::pair<SnoopList, Cycles> lookupSnoop(const Packet* cpkt);
/**
- * Let the snoop filter see any snoop responses that turn into request responses
- * and indicate cache to cache transfers. These will update the corresponding
- * state in the filter.
+ * Let the snoop filter see any snoop responses that turn into
+ * request responses and indicate cache to cache transfers. These
+ * will update the corresponding state in the filter.
*
* @param cpkt Pointer to const Packet holding the snoop response.
* @param rsp_port SlavePort that sends the response.
const SlavePort& req_port);
/**
- * Pass snoop responses that travel downward through the snoop filter and let
- * them update the snoop filter state. No additional routing happens.
+ * Pass snoop responses that travel downward through the snoop
+ * filter and let them update the snoop filter state. No
+ * additional routing happens.
*
* @param cpkt Pointer to const Packet holding the snoop response.
* @param rsp_port SlavePort that sends the response.
- * @param req_port MasterPort through which the response leaves this cluster.
+ * @param req_port MasterPort through which the response is forwarded.
*/
void updateSnoopForward(const Packet *cpkt, const SlavePort& rsp_port,
const MasterPort& req_port);
/**
- * Update the snoop filter with a response from below (outer / other cache,
- * or memory) and update the tracking information in the snoop filter.
+ * Update the snoop filter with a response from below (outer /
+ * other cache, or memory) and update the tracking information in
+ * the snoop filter.
*
* @param cpkt Pointer to const Packet holding the snoop response.
- * @param slave_port SlavePort that made the original request and is the target
- * of this response.
+ * @param slave_port SlavePort that made the original request and
+ * is the target of this response.
*/
void updateResponse(const Packet *cpkt, const SlavePort& slave_port);
+ virtual void regStats();
+
+ protected:
+
+ /**
+ * The underlying type for the bitmask we use for tracking. This
+ * limits the number of snooping ports supported per crossbar. For
+ * the moment it is an uint64_t to offer maximum
+ * scalability. However, it is possible to use e.g. a uint16_t or
+ * uint32_to slim down the footprint of the hash map (and
+ * ultimately improve the simulation performance).
+ */
+ typedef uint64_t SnoopMask;
+
+ /**
+ * Per cache line item tracking a bitmask of SlavePorts who have an
+ * outstanding request to this line (requested) or already share a
+ * cache line with this address (holder).
+ */
+ struct SnoopItem {
+ SnoopMask requested;
+ SnoopMask holder;
+ };
+ /**
+ * HashMap of SnoopItems indexed by line address
+ */
+ typedef m5::hash_map<Addr, SnoopItem> SnoopFilterCache;
+
/**
- * Simple factory methods for standard return values for lookupRequest
+ * Simple factory methods for standard return values.
*/
std::pair<SnoopList, Cycles> snoopAll(Cycles latency) const
{
return std::make_pair(empty , latency);
}
- virtual void regStats();
-
- protected:
- typedef uint64_t SnoopMask;
- /**
- * Per cache line item tracking a bitmask of SlavePorts who have an
- * outstanding request to this line (requested) or already share a cache line
- * with this address (holder).
- */
- struct SnoopItem {
- SnoopMask requested;
- SnoopMask holder;
- };
- /**
- * HashMap of SnoopItems indexed by line address
- */
- typedef m5::hash_map<Addr, SnoopItem> SnoopFilterCache;
-
/**
* Convert a single port to a corresponding, one-hot bitmask
* @param port SlavePort that should be converted.
* Removes snoop filter items which have no requesters and no holders.
*/
void eraseIfNullEntry(SnoopFilterCache::iterator& sf_it);
+
/** Simple hash set of cached addresses. */
SnoopFilterCache cachedLocations;
/**
res.push_back(p);
return res;
}
+
#endif // __MEM_SNOOP_FILTER_HH__
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