mem: Sort memory commands and update DRAMPower

Add local variable to stores commands to be issued.
These commands are in order within a single bank but will be out
of order across banks & ranks.

A new procedure, flushCmdList, sorts commands across banks / ranks,
and flushes the sorted list, up to curTick() to DRAMPower.
This is currently called in refresh, once all previous commands are
guaranteed to have completed.  Could be called in other events like
the powerEvent as well.

By only flushing commands up to curTick(), will not get out of sync
when flushed at a periodic stats dump (done in subsequent patch).

Change-Id: I4ac65a52407f64270db1e16a1fb04cfe7f638851
Reviewed-by: Radhika Jagtap <radhika.jagtap@arm.com>

1 files changed, 38 insertions, 9 deletions

diff --git a/src/mem/dram_ctrl.hh b/src/mem/dram_ctrl.hh
index 98f47edc2..70b737652 100644
--- a/src/mem/dram_ctrl.hh
+++ b/src/mem/dram_ctrl.hh
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2012-2015 ARM Limited
+ * Copyright (c) 2012-2016 ARM Limited
  * All rights reserved
  *
  * The license below extends only to copyright in the software and shall
@@ -147,6 +147,21 @@ class DRAMCtrl : public AbstractMemory
     BusState busState;
 
     /**
+     * Simple structure to hold the values needed to keep track of
+     * commands for DRAMPower
+     */
+    struct Command {
+       Data::MemCommand::cmds type;
+       uint8_t bank;
+       Tick timeStamp;
+
+       constexpr Command(Data::MemCommand::cmds _type, uint8_t _bank,
+                         Tick time_stamp)
+            : type(_type), bank(_bank), timeStamp(time_stamp)
+        { }
+    };
+
+    /**
      * A basic class to track the bank state, i.e. what row is
      * currently open (if any), when is the bank free to accept a new
      * column (read/write) command, when can it be precharged, and
@@ -317,6 +332,14 @@ class DRAMCtrl : public AbstractMemory
         DRAMPower power;
 
         /**
+         * List of comamnds issued, to be sent to DRAMPpower at refresh
+         * and stats dump.  Keep commands here since commands to different
+         * banks are added out of order.  Will only pass commands up to
+         * curTick() to DRAMPower after sorting.
+         */
+        std::vector<Command> cmdList;
+
+        /**
          * Vector of Banks. Each rank is made of several devices which in
          * term are made from several banks.
          */
@@ -364,6 +387,14 @@ class DRAMCtrl : public AbstractMemory
          */
         void checkDrainDone();
 
+        /**
+         * Push command out of cmdList queue that are scheduled at
+         * or before curTick() to DRAMPower library
+         * All commands before curTick are guaranteed to be complete
+         * and can safely be flushed.
+         */
+        void flushCmdList();
+
         /*
          * Function to register Stats
          */
@@ -857,18 +888,16 @@ class DRAMCtrl : public AbstractMemory
     void updatePowerStats(Rank& rank_ref);
 
     /**
-     * Function for sorting commands in the command list of DRAMPower.
+     * Function for sorting Command structures based on timeStamp
      *
-     * @param a Memory Command in command list of DRAMPower library
-     * @param next Memory Command in command list of DRAMPower
-     * @return true if timestamp of Command 1 < timestamp of Command 2
+     * @param a Memory Command
+     * @param next Memory Command
+     * @return true if timeStamp of Command 1 < timeStamp of Command 2
      */
-    static bool sortTime(const Data::MemCommand& m1,
-                         const Data::MemCommand& m2) {
-        return m1.getTimeInt64() < m2.getTimeInt64();
+    static bool sortTime(const Command& cmd, const Command& cmd_next) {
+        return cmd.timeStamp < cmd_next.timeStamp;
     };
 
-
   public:
 
     void regStats() override;