Changeset 1011 for branches/reconfiguration/modules/vci_mem_cache/caba/source/include

Timestamp:

Aug 15, 2015, 9:02:55 PM (9 years ago)

Author:

cfuguet

Message:

reconf: introduce a scratchpad mode in the memory cache.

• Initialize the memory cache directory with all slots valid. The cache lines correspond to the lowest local memory segment (i.e. the first 256 Kbytes).

• If there is a read or write miss while in scratchpad mode, the request is dropped (black-hole behavior).

• In scratchpad mode, when a broadcast invalidate is triggered by a write, the line is not invalidated. The Read FSM needs to check in the IVT if there is a pending invalidate during a read. The same for the Cleanup FSM. This additional IVT check is only performed when in scratchpad mode.

• TODO: Support of the scratchpad mode on the CAS FSM. But probably not needed because the distributed bootloader initializes the Local, Remote and Dirty flags to 1 before enabling the MMU.

Location:

branches/reconfiguration/modules/vci_mem_cache/caba/source/include

Files:

• mem_cache_directory.h (modified) (2 diffs)
• vci_mem_cache.h (modified) (6 diffs)

branches/reconfiguration/modules/vci_mem_cache/caba/source/include/mem_cache_directory.h

@@ -305 +305 @@
                const DirectoryEntry &entry)
     {
-        assert((set < m_sets) && "Cache Directory write : The set index is invalid");
-        assert((way < m_ways) && "Cache Directory write : The way index is invalid");
-
-        // update Directory
-        m_dir_tab[set][way].copy(entry);
+        write_neutral(set, way, entry);
 
         // update LRU bits
@@ -326 +322 @@
         }
     } // end write()
+
+    /////////////////////////////////////////////////////////////////////
+    // The write_neutral function writes a new entry,
+    // without changing the LRU.
+    // Arguments :
+    // - set : the set of the entry
+    // - way : the way of the entry
+    // - entry : the entry value
+    /////////////////////////////////////////////////////////////////////
+    void write_neutral(const size_t &set,
+                       const size_t &way,
+                       const DirectoryEntry &entry)
+    {
+        assert((set < m_sets) && "Cache Directory write : The set index is invalid");
+        assert((way < m_ways) && "Cache Directory write : The way index is invalid");
+
+        // update Directory
+        m_dir_tab[set][way].copy(entry);
+    } // end write_neutral()
 
     /////////////////////////////////////////////////////////////////////

branches/reconfiguration/modules/vci_mem_cache/caba/source/include/vci_mem_cache.h

@@ -202 +202 @@
         READ_TRT_LOCK,
         READ_TRT_SET,
-        READ_TRT_REQ
+        READ_TRT_REQ,
+        READ_IVT_LOCK
       };
 
@@ -367 +368 @@
         ALLOC_IVT_CLEANUP,
         ALLOC_IVT_CAS,
-        ALLOC_IVT_CONFIG
+        ALLOC_IVT_CONFIG,
+        ALLOC_IVT_READ
       };
 
@@ -540 +542 @@
       private:
 
+      void scratchpad_reset();
       void transition();
       void genMoore();
@@ -644 +647 @@
       //////////////////////////////////////////////////
 
-      sc_signal<int>         r_tgt_cmd_fsm;
+      sc_signal<int>      r_tgt_cmd_fsm;
 
       ///////////////////////////////////////////////////////
@@ -668 +671 @@
       sc_signal<size_t>   r_config_trt_index;         // selected entry in TRT
       sc_signal<size_t>   r_config_ivt_index;         // selected entry in IVT
+      sc_signal<bool>     r_config_scratchpad;        // enable scratchpad mode
 
       // Buffer between CONFIG fsm and IXR_CMD fsm
@@ -820 +824 @@
       sc_signal<size_t>   r_cleanup_next_ptr;      // next pointer to the heap
       sc_signal<tag_t>    r_cleanup_tag;           // cache line tag (in directory)
+      sc_signal<bool>     r_cleanup_valid;         // valid bit (in directory)
       sc_signal<bool>     r_cleanup_is_cnt;        // inst bit (in directory)
       sc_signal<bool>     r_cleanup_lock;          // lock bit (in directory)