added Linux KSM support

master.c

@@ -1432,6 +1432,14 @@ healthy:
 			}
 #endif
 
+#ifdef __linux__
+#ifdef MADV_MERGEABLE
+			if (uwsgi.linux_ksm > 0 && (uwsgi.master_cycles % uwsgi.linux_ksm) == 0) {
+				uwsgi_linux_ksm_map();
+			}
+#endif
+#endif
+
 #ifdef UWSGI_UDP
 			// check for cluster nodes
 			master_check_cluster_nodes();

utils.c

@@ -717,8 +717,96 @@ void uwsgi_close_request(struct wsgi_request *wsgi_req) {
 		uwsgi.loyal = 1;
 	}
 
+#ifdef __linux__
+#ifdef MADV_MERGEABLE
+	// run the ksm mapper
+	if (uwsgi.linux_ksm > 0 && (uwsgi.workers[uwsgi.mywid].requests % uwsgi.linux_ksm) == 0) {
+		uwsgi_linux_ksm_map();
+	}
+#endif
+#endif
+
 }
 
+#ifdef __linux__
+#ifdef MADV_MERGEABLE
+
+unsigned long long *ksm_mappings_last = NULL;
+int ksm_mappings_last_lines = 0;
+unsigned long long *ksm_mappings_current = NULL;
+int ksm_mappings_current_lines = 0;
+
+void uwsgi_linux_ksm_map(void) {
+
+	char map_line_buf[1024];
+        unsigned long long start, end;
+	int dirty = 0;
+	int i;
+	int errors = 0;
+	unsigned long long *tmp_ptr;
+
+	ksm_mappings_current = NULL;
+	ksm_mappings_current_lines = 0;
+
+        FILE *process_maps = fopen("/proc/self/maps", "r");
+
+        if (process_maps) {
+        	while( fgets(map_line_buf, 1024, process_maps)) {
+                	if (fscanf(process_maps, "%llx-%llx %*s", &start, &end) == 2) {
+				ksm_mappings_current_lines+=2;
+				tmp_ptr = ksm_mappings_current;
+				ksm_mappings_current = realloc(ksm_mappings_current, sizeof(unsigned long long) * ksm_mappings_current_lines);
+				if (!ksm_mappings_current) {
+					uwsgi_error("[uwsgi-KSM] /proc/self/maps realloc()");
+					fclose(process_maps);
+					if (tmp_ptr) {
+						free(tmp_ptr);
+					}
+					return;
+				}
+				ksm_mappings_current[ksm_mappings_current_lines-2] = start;
+				ksm_mappings_current[ksm_mappings_current_lines-1] = end;
+                        }
+		}
+		fclose(process_maps);
+
+		if (ksm_mappings_last == NULL || ksm_mappings_last_lines == 0 || ksm_mappings_last_lines != ksm_mappings_current_lines) {
+			dirty = 1;
+		}
+		else {
+			for(i=0;i<ksm_mappings_current_lines;i+=2) {
+				if (ksm_mappings_current[i] != ksm_mappings_last[i]) {
+					dirty = 1;
+					break;
+				}
+				if (ksm_mappings_current[i+1] != ksm_mappings_last[i+1]) {
+					dirty = 1;
+					break;
+				}
+			}
+		}
+
+		if (dirty) {
+
+			for(i=0;i<ksm_mappings_current_lines;i+=2) {
+                		if (madvise((void *) (long) ksm_mappings_current[i], (size_t) (ksm_mappings_current[i+1]-ksm_mappings_current[i]), MADV_MERGEABLE)) {
+					errors += 2;
+                		}
+			}
+
+			free(ksm_mappings_last);
+			ksm_mappings_last = ksm_mappings_current;
+			ksm_mappings_last_lines = ksm_mappings_current_lines;
+
+			if (errors >= ksm_mappings_current_lines) {
+				uwsgi_error("[uwsgi-KSM] unable to share pages");
+			}
+		}
+	}
+}
+#endif
+#endif
+
 void wsgi_req_setup(struct wsgi_request *wsgi_req, int async_id, struct uwsgi_socket *uwsgi_sock) {
 
 	wsgi_req->poll.events = POLLIN;

uwsgi.c

@@ -176,6 +176,11 @@ static struct option long_base_options[] = {
 	{"reload-on-rss", required_argument, 0, LONG_ARGS_RELOAD_ON_RSS},
 	{"evil-reload-on-as", required_argument, 0, LONG_ARGS_EVIL_RELOAD_ON_AS},
 	{"evil-reload-on-rss", required_argument, 0, LONG_ARGS_EVIL_RELOAD_ON_RSS},
+#ifdef __linux__
+#ifdef MADV_MERGEABLE
+	{"ksm", optional_argument, 0, LONG_ARGS_KSM},
+#endif
+#endif
 	{"touch-reload", required_argument, 0, LONG_ARGS_TOUCH_RELOAD},
 	{"propagate-touch", no_argument, &uwsgi.propagate_touch, 1},
 	{"limit-post", required_argument, 0, LONG_ARGS_LIMIT_POST},
@@ -2442,6 +2447,7 @@ skipzero:
 	}
 
 
+
 	if (!uwsgi.master_process && uwsgi.numproc == 0) {
 		exit(0);
 	}
@@ -2449,6 +2455,16 @@ skipzero:
 		uwsgi_log("*** uWSGI is running in multiple interpreter mode ***\n");
 	}
 
+#ifdef __linux__
+#ifdef MADV_MERGEABLE
+	if (uwsgi.linux_ksm > 0) {
+		uwsgi_log("[uwsgi-KSM] enabled with frequency: %d\n", uwsgi.linux_ksm); 
+	}
+#endif
+#endif
+
+
+
 	if (uwsgi.master_process) {
 		if (uwsgi.is_a_reload) {
 			uwsgi_log("gracefully (RE)spawned uWSGI master process (pid: %d)\n", uwsgi.mypid);
@@ -2541,6 +2557,8 @@ skipzero:
 		}
 	}
 
+
+
 	if (getpid() == masterpid && uwsgi.master_process == 1) {
 #ifdef UWSGI_AS_SHARED_LIBRARY
 		int ml_ret = master_loop(uwsgi.argv, uwsgi.environ);
@@ -3415,6 +3433,16 @@ static int manage_base_opt(int i, char *optarg) {
 	case LONG_ARGS_LIMIT_POST:
 		uwsgi.limit_post = (int) strtol(optarg, NULL, 10);
 		return 1;
+#ifdef __linux__
+#ifdef MADV_MERGEABLE
+	case LONG_ARGS_KSM:
+		uwsgi.linux_ksm = 1;
+		if (optarg) {
+			uwsgi.linux_ksm = atoi(optarg);
+		}
+		return 1;
+#endif
+#endif
 	case LONG_ARGS_RELOAD_ON_AS:
 		uwsgi.force_get_memusage = 1;
 		uwsgi.reload_on_as = (strtoul(optarg, NULL, 10)) * 1024 * 1024;

uwsgi.h

@@ -540,6 +540,7 @@ struct uwsgi_opt {
 #define LONG_ARGS_PAUSE			17161
 #define LONG_ARGS_SIGNAL_BUFSIZE	17162
 #define LONG_ARGS_SIGNAL		17163
+#define LONG_ARGS_KSM			17164
 
 
 #define UWSGI_OK	0
@@ -1525,6 +1526,12 @@ struct uwsgi_server {
 	// subscription client
 	struct uwsgi_string_list *subscriptions;
 
+#ifdef __linux__
+#ifdef MADV_MERGEABLE
+	int linux_ksm;
+#endif
+#endif
+
 };
 
 struct uwsgi_rpc {
@@ -2459,6 +2466,12 @@ void uwsgi_add_app(int, uint8_t, char *, int);
 int uwsgi_signal_send(int, uint8_t);
 int uwsgi_remote_signal_send(char *, uint8_t); 
 
+#ifdef __linux__
+#ifdef MADV_MERGEABLE
+void uwsgi_linux_ksm_map(void);
+#endif
+#endif
+
 #ifdef UWSGI_CAP
 void uwsgi_build_cap(char *);
 #endif