mem: Use STL deque in favour of list for DRAM queues

This patch changes the data structure used for the DRAM read, write
and response queues from an STL list to deque. This optimisation is
based on the observation that the size is small (and fixed), and that
the structures are frequently iterated over in a linear fashion.

diff --git a/src/mem/simple_dram.cc b/src/mem/simple_dram.cc
index e8c1dfbcd93bcbd348b9ab18223cf91b7a5b24a3..033ccbb26443e3f9da894531a35b32fbf490b180 100644 (file)
--- a/src/mem/simple_dram.cc
+++ b/src/mem/simple_dram.cc
@@ -310,8 +310,7 @@ SimpleDRAM::addToReadQueue(PacketPtr pkt, unsigned int pktCount)
         // First check write buffer to see if the data is already at
         // the controller
         bool foundInWrQ = false;
-        list<DRAMPacket*>::const_iterator i;
-        for (i = writeQueue.begin(); i != writeQueue.end(); ++i) {
+        for (auto i = writeQueue.begin(); i != writeQueue.end(); ++i) {
             // check if the read is subsumed in the write entry we are
             // looking at
             if ((*i)->addr <= addr &&
@@ -662,19 +661,16 @@ SimpleDRAM::printParams() const
 
 void
 SimpleDRAM::printQs() const {
-
-    list<DRAMPacket*>::const_iterator i;
-
     DPRINTF(DRAM, "===READ QUEUE===\n\n");
-    for (i = readQueue.begin() ;  i != readQueue.end() ; ++i) {
+    for (auto i = readQueue.begin() ;  i != readQueue.end() ; ++i) {
         DPRINTF(DRAM, "Read %lu\n", (*i)->addr);
     }
     DPRINTF(DRAM, "\n===RESP QUEUE===\n\n");
-    for (i = respQueue.begin() ;  i != respQueue.end() ; ++i) {
+    for (auto i = respQueue.begin() ;  i != respQueue.end() ; ++i) {
         DPRINTF(DRAM, "Response %lu\n", (*i)->addr);
     }
     DPRINTF(DRAM, "\n===WRITE QUEUE===\n\n");
-    for (i = writeQueue.begin() ;  i != writeQueue.end() ; ++i) {
+    for (auto i = writeQueue.begin() ;  i != writeQueue.end() ; ++i) {
         DPRINTF(DRAM, "Write %lu\n", (*i)->addr);
     }
 }
@@ -829,7 +825,7 @@ SimpleDRAM::chooseNextWrite()
     if (memSchedPolicy == Enums::fcfs) {
         // Do nothing, since the correct request is already head
     } else if (memSchedPolicy == Enums::frfcfs) {
-        list<DRAMPacket*>::iterator i = writeQueue.begin();
+        auto i = writeQueue.begin();
         bool foundRowHit = false;
         while (!foundRowHit && i != writeQueue.end()) {
             DRAMPacket* dram_pkt = *i;
@@ -870,8 +866,7 @@ SimpleDRAM::chooseNextRead()
         // Do nothing, since the request to serve is already the first
         // one in the read queue
     } else if (memSchedPolicy == Enums::frfcfs) {
-        for (list<DRAMPacket*>::iterator i = readQueue.begin();
-             i != readQueue.end() ; ++i) {
+        for (auto i = readQueue.begin(); i != readQueue.end() ; ++i) {
             DRAMPacket* dram_pkt = *i;
             const Bank& bank = dram_pkt->bank_ref;
             // Check if it is a row hit
@@ -1153,7 +1148,7 @@ SimpleDRAM::moveToRespQ()
         schedule(respondEvent, dram_pkt->readyTime);
     } else {
         bool done = false;
-        list<DRAMPacket*>::iterator i = respQueue.begin();
+        auto i = respQueue.begin();
         while (!done && i != respQueue.end()) {
             if ((*i)->readyTime > dram_pkt->readyTime) {
                 respQueue.insert(i, dram_pkt);

diff --git a/src/mem/simple_dram.hh b/src/mem/simple_dram.hh
index 9473f010fd83dc11d0bc94b171e1d6eabe8a10c5..abc64c3cd3794ea5ba82e94acbd4878512dd1753 100644 (file)
--- a/src/mem/simple_dram.hh
+++ b/src/mem/simple_dram.hh
@@ -406,8 +406,8 @@ class SimpleDRAM : public AbstractMemory
     /**
      * The controller's main read and write queues
      */
-    std::list<DRAMPacket*> readQueue;
-    std::list<DRAMPacket*> writeQueue;
+    std::deque<DRAMPacket*> readQueue;
+    std::deque<DRAMPacket*> writeQueue;
 
     /**
      * Response queue where read packets wait after we're done working
@@ -417,7 +417,7 @@ class SimpleDRAM : public AbstractMemory
      * as sizing the read queue, this and the main read queue need to
      * be added together.
      */
-    std::list<DRAMPacket*> respQueue;
+    std::deque<DRAMPacket*> respQueue;
 
     /**
      * If we need to drain, keep the drain manager around until we're