queue.hh

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#ifndef __MEM_CACHE_QUEUE_HH__
#define __MEM_CACHE_QUEUE_HH__
 
#include <cassert>
#include <string>
#include <type_traits>
 
#include "base/logging.hh"
#include "base/named.hh"
#include "base/trace.hh"
#include "base/types.hh"
#include "debug/Drain.hh"
#include "mem/cache/queue_entry.hh"
#include "mem/packet.hh"
#include "sim/cur_tick.hh"
#include "sim/drain.hh"
 
namespace gem5
{
 
template<class Entry>
class Queue : public Drainable, public Named
{
    static_assert(std::is_base_of_v<QueueEntry, Entry>,
        "Entry must be derived from QueueEntry");
 
  protected:
    const std::string label;
 
    const int numEntries;
 
    const int numReserve;
 
    std::vector<Entry> entries;
    typename Entry::List allocatedList;
    typename Entry::List readyList;
    typename Entry::List freeList;
 
    typename Entry::Iterator addToReadyList(Entry* entry)
    {
        if (readyList.empty() ||
            readyList.back()->readyTime <= entry->readyTime) {
            return readyList.insert(readyList.end(), entry);
        }
 
        for (auto i = readyList.begin(); i != readyList.end(); ++i) {
            if ((*i)->readyTime > entry->readyTime) {
                return readyList.insert(i, entry);
            }
        }
        panic("Failed to add to ready list.");
    }
 
    int _numInService;
 
    int allocated;
 
  public:
 
    Queue(const std::string &_label, int num_entries, int reserve,
            const std::string &name) :
        Named(name),
        label(_label), numEntries(num_entries + reserve),
        numReserve(reserve), entries(numEntries, name + ".entry"),
        _numInService(0), allocated(0)
    {
        for (int i = 0; i < numEntries; ++i) {
            freeList.push_back(&entries[i]);
        }
    }
 
    bool isEmpty() const
    {
        return allocated == 0;
    }
 
    bool isFull() const
    {
        return (allocated >= numEntries - numReserve);
    }
 
    int numInService() const
    {
        return _numInService;
    }
 
    Entry* findMatch(Addr blk_addr, bool is_secure,
                     bool ignore_uncacheable = true) const
    {
        for (const auto& entry : allocatedList) {
            // we ignore any entries allocated for uncacheable
            // accesses and simply ignore them when matching, in the
            // cache we never check for matches when adding new
            // uncacheable entries, and we do not want normal
            // cacheable accesses being added to an WriteQueueEntry
            // serving an uncacheable access
            if (!(ignore_uncacheable && entry->isUncacheable()) &&
                entry->matchBlockAddr(blk_addr, is_secure)) {
                return entry;
            }
        }
        return nullptr;
    }
 
    bool trySatisfyFunctional(PacketPtr pkt)
    {
        pkt->pushLabel(label);
        for (const auto& entry : allocatedList) {
            if (entry->matchBlockAddr(pkt) &&
                entry->trySatisfyFunctional(pkt)) {
                pkt->popLabel();
                return true;
            }
        }
        pkt->popLabel();
        return false;
    }
 
    Entry* findPending(const QueueEntry* entry) const
    {
        for (const auto& ready_entry : readyList) {
            if (ready_entry->conflictAddr(entry)) {
                return ready_entry;
            }
        }
        return nullptr;
    }
 
    Entry* getNext() const
    {
        if (readyList.empty() || readyList.front()->readyTime > curTick()) {
            return nullptr;
        }
        return readyList.front();
    }
 
    Tick nextReadyTime() const
    {
        return readyList.empty() ? MaxTick : readyList.front()->readyTime;
    }
 
    virtual void
    deallocate(Entry *entry)
    {
        allocatedList.erase(entry->allocIter);
        freeList.push_front(entry);
        allocated--;
        if (entry->inService) {
            _numInService--;
        } else {
            readyList.erase(entry->readyIter);
        }
        entry->deallocate();
        if (drainState() == DrainState::Draining && allocated == 0) {
            // Notify the drain manager that we have completed
            // draining if there are no other outstanding requests in
            // this queue.
            DPRINTF(Drain, "Queue now empty, signalling drained\n");
            signalDrainDone();
        }
    }
 
    DrainState drain() override
    {
        return allocated == 0 ? DrainState::Drained : DrainState::Draining;
    }
};
 
} // namespace gem5
 
#endif //__MEM_CACHE_QUEUE_HH__