From d6cb1de320b36257e60144a513beaf9a96b87700 Mon Sep 17 00:00:00 2001
From: Lukas Steiner <lsteiner@rhrk.uni-kl.de>
Date: Fri, 18 Sep 2020 15:01:24 +0200
Subject: [PATCH] Improve FR-FCFS scheduler.

---
 .../controller/scheduler/SchedulerFrFcfs.cpp  | 25 ++++++++-----------
 .../controller/scheduler/SchedulerFrFcfs.h    |  3 ++-
 2 files changed, 13 insertions(+), 15 deletions(-)

diff --git a/DRAMSys/library/src/controller/scheduler/SchedulerFrFcfs.cpp b/DRAMSys/library/src/controller/scheduler/SchedulerFrFcfs.cpp
index 48ecad08..b29bcb73 100644
--- a/DRAMSys/library/src/controller/scheduler/SchedulerFrFcfs.cpp
+++ b/DRAMSys/library/src/controller/scheduler/SchedulerFrFcfs.cpp
@@ -41,9 +41,13 @@ using namespace tlm;
 
 SchedulerFrFcfs::SchedulerFrFcfs()
 {
-    buffer = std::vector<std::list<tlm_generic_payload *>>
+    buffer = std::vector<std::vector<tlm_generic_payload *>>
             (Configuration::getInstance().memSpec->numberOfBanks);
     requestBufferSize = Configuration::getInstance().requestBufferSize;
+    lastRequest = std::vector<std::vector<tlm::tlm_generic_payload *>::iterator>
+            (Configuration::getInstance().memSpec->numberOfBanks);
+    for (auto it : buffer)
+        it.reserve(requestBufferSize);
 }
 
 bool SchedulerFrFcfs::hasBufferSpace()
@@ -63,15 +67,7 @@ void SchedulerFrFcfs::storeRequest(tlm_generic_payload *payload)
 void SchedulerFrFcfs::removeRequest(tlm_generic_payload *payload)
 {
     unsigned bankID = DramExtension::getBank(payload).ID();
-    for (auto it = buffer[bankID].begin(); it != buffer[bankID].end(); it++)
-    {
-        if (*it == payload)
-        {
-            buffer[bankID].erase(it);
-            return;
-        }
-    }
-    SC_REPORT_FATAL("SchedulerFrFcfs", "removeRequest failed!");
+    buffer[bankID].erase(lastRequest[bankID]);
 }
 
 tlm_generic_payload *SchedulerFrFcfs::getNextRequest(BankMachine *bankMachine)
@@ -86,10 +82,14 @@ tlm_generic_payload *SchedulerFrFcfs::getNextRequest(BankMachine *bankMachine)
             for (auto it = buffer[bankID].begin(); it != buffer[bankID].end(); it++)
             {
                 if (DramExtension::getRow(*it) == openRow)
+                {
+                    lastRequest[bankID] = it;
                     return *it;
+                }
             }
         }
         // No row hit found or bank precharged
+        lastRequest[bankID] = buffer[bankID].begin();
         return buffer[bankID].front();
     }
     return nullptr;
@@ -112,8 +112,5 @@ bool SchedulerFrFcfs::hasFurtherRowHit(Bank bank, Row row)
 
 bool SchedulerFrFcfs::hasFurtherRequest(Bank bank)
 {
-    if (buffer[bank.ID()].size() >= 2)
-        return true;
-    else
-        return false;
+    return (buffer[bank.ID()].size() >= 2);
 }
diff --git a/DRAMSys/library/src/controller/scheduler/SchedulerFrFcfs.h b/DRAMSys/library/src/controller/scheduler/SchedulerFrFcfs.h
index 5d5347a4..b8174752 100644
--- a/DRAMSys/library/src/controller/scheduler/SchedulerFrFcfs.h
+++ b/DRAMSys/library/src/controller/scheduler/SchedulerFrFcfs.h
@@ -53,9 +53,10 @@ public:
     virtual bool hasFurtherRowHit(Bank, Row) override;
     virtual bool hasFurtherRequest(Bank) override;
 private:
-    std::vector<std::list<tlm::tlm_generic_payload *>> buffer;
+    std::vector<std::vector<tlm::tlm_generic_payload *>> buffer;
     unsigned requestBufferSize;
     unsigned lastBankID;
+    std::vector<std::vector<tlm::tlm_generic_payload *>::iterator> lastRequest;
 };
 
 #endif // SCHEDULERFRFCFS_H