Add hashtable-on-dram option

redis.conf

@@ -1122,3 +1122,6 @@ dynamic-threshold-max 10000
 
 # DRAM/PMEM ratio period measured in miliseconds
 memory-ratio-check-period 100
+
+# Keep hashtable structure always on DRAM
+hashtable-on-dram yes

src/config.c

@@ -335,6 +335,10 @@ void loadServerConfigFromString(char *config) {
             if (server.ratio_check_period < 1) {
                 err = "Invalid number of memory ratio check period"; goto loaderr;
             }
+        } else if (!strcasecmp(argv[0],"hashtable-on-dram") && argc == 2) {
+            if ((server.hashtable_on_dram = yesnotoi(argv[1])) == -1) {
+                err = "argument must be 'yes' or 'no'"; goto loaderr;
+            }
         } else if (!strcasecmp(argv[0],"maxmemory") && argc == 2) {
             server.maxmemory = memtoll(argv[1],NULL);
         } else if (!strcasecmp(argv[0],"maxmemory-policy") && argc == 2) {
@@ -1210,6 +1214,8 @@ void configGetCommand(client *c) {
             server.aof_rewrite_incremental_fsync);
     config_get_bool_field("aof-load-truncated",
             server.aof_load_truncated);
+    config_get_bool_field("hashtable-on-dram",
+            server.hashtable_on_dram);
 
     /* Enum values */
     config_get_enum_field("maxmemory-policy",

src/dict.c

@@ -57,6 +57,7 @@
  * the number of elements and the buckets > dict_force_resize_ratio. */
 static int dict_can_resize = 1;
 static unsigned int dict_force_resize_ratio = 5;
+static int dict_always_on_dram = 1;
 
 /* -------------------------- private prototypes ---------------------------- */
 
@@ -89,6 +90,10 @@ uint32_t dictGetHashFunctionSeed(void) {
     return dict_hash_function_seed;
 }
 
+void dictSetAllocPolicy(int policy) {
+    dict_always_on_dram = policy;
+}
+
 /* MurmurHash2, by Austin Appleby
  * Note - This code makes a few assumptions about how your machine behaves -
  * 1. We can read a 4-byte value from any address without crashing
@@ -217,7 +222,7 @@ int dictExpand(dict *d, unsigned long size)
     /* Allocate the new hash table and initialize all pointers to NULL */
     n.size = realsize;
     n.sizemask = realsize-1;
-    n.table = zcalloc_dram(realsize*sizeof(dictEntry*));
+    n.table = (dict_always_on_dram) ? zcalloc_dram(realsize*sizeof(dictEntry*)) : zcalloc(realsize*sizeof(dictEntry*));
     n.used = 0;
 
     /* Is this the first initialization? If so it's not really a rehashing
@@ -276,7 +281,7 @@ int dictRehash(dict *d, int n) {
 
     /* Check if we already rehashed the whole table... */
     if (d->ht[0].used == 0) {
-        zfree_dram(d->ht[0].table);
+        zfree(d->ht[0].table);
         d->ht[0] = d->ht[1];
         _dictReset(&d->ht[1]);
         d->rehashidx = -1;
@@ -475,7 +480,7 @@ int _dictClear(dict *d, dictht *ht, void(callback)(void *)) {
         }
     }
     /* Free the table and the allocated cache structure */
-    zfree_dram(ht->table);
+    zfree(ht->table);
     /* Re-initialize the table */
     _dictReset(ht);
     return DICT_OK; /* never fails */

src/dict.h

@@ -174,6 +174,7 @@ void dictDisableResize(void);
 int dictRehash(dict *d, int n);
 int dictRehashMilliseconds(dict *d, int ms);
 void dictSetHashFunctionSeed(unsigned int initval);
+void dictSetAllocPolicy(int policy);
 unsigned int dictGetHashFunctionSeed(void);
 unsigned long dictScan(dict *d, unsigned long v, dictScanFunction *fn, void *privdata);
 

src/server.c

@@ -1520,6 +1520,7 @@ void initServerConfig(void) {
     server.activerehashing = CONFIG_DEFAULT_ACTIVE_REHASHING;
     server.notify_keyspace_events = 0;
     server.maxclients = CONFIG_DEFAULT_MAX_CLIENTS;
+    server.hashtable_on_dram = 1;
     server.bpop_blocked_clients = 0;
     server.maxmemory = CONFIG_DEFAULT_MAXMEMORY;
     server.maxmemory_policy = CONFIG_DEFAULT_MAXMEMORY_POLICY;
@@ -2015,6 +2016,7 @@ void initServer(void) {
     slowlogInit();
     latencyMonitorInit();
     pmemThresholdInit();
+    dictSetAllocPolicy(server.hashtable_on_dram);
     bioInit();
 }
 

src/server.h

@@ -933,6 +933,7 @@ struct redisServer {
     ratioDramPmemConfig dram_pmem_ratio;      /* DRAM/Persistent Memory ratio */
     double target_pmem_dram_ratio;            /* Target PMEM/DRAM ratio */
     int ratio_check_period;                   /* Period of checking ratio in Cron*/
+    int hashtable_on_dram;                    /* Keep hashtable always on DRAM */
     /* Blocked clients */
     unsigned int bpop_blocked_clients; /* Number of clients blocked by lists */
     list *unblocked_clients; /* list of clients to unblock before next loop */