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mem: Comment clean-up for the snoop filter

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Merely fixing up some style issues and adding more comments.
This commit is contained in:
Andreas Hansson 2015-09-25 07:26:57 -04:00
parent 7d4e89d4e0
commit 5570aa9e9a
2 changed files with 54 additions and 39 deletions
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4
src/mem/snoop_filter.cc
View file

@ -34,12 +34,12 @@
* (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
*/
/**
* @file
* Definition of a snoop filter.
* Implementation of a snoop filter.
*/
#include "base/misc.hh"

89
src/mem/snoop_filter.hh
View file

@ -34,7 +34,7 @@
* (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
*/
/**
@ -96,8 +96,8 @@ class SnoopFilter : public SimObject {
}
/**
* 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.
*/
@ -127,7 +127,7 @@ class SnoopFilter : public SimObject {
* 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.
*/
@ -141,14 +141,15 @@ class SnoopFilter : public SimObject {
* 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.
@ -156,9 +157,9 @@ class SnoopFilter : public SimObject {
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.
@ -169,28 +170,58 @@ class SnoopFilter : public SimObject {
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:
/**
* Simple factory methods for standard return values for lookupRequest
* 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.
*/
std::pair<SnoopList, Cycles> snoopAll(Cycles latency) const
{
@ -207,24 +238,6 @@ class SnoopFilter : public SimObject {
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.
@ -244,6 +257,7 @@ class SnoopFilter : public SimObject {
* 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;
/**
@ -296,4 +310,5 @@ SnoopFilter::maskToPortList(SnoopMask port_mask) const
res.push_back(p);
return res;
}
#endif // __MEM_SNOOP_FILTER_HH__