mem: improve pre-allocation

kernel/Kconfig

@@ -223,6 +223,17 @@ config MARS_MEM_PREALLOC
 	help
 	Normally ON. Switch off only for EXPERIMENTS!
 
+config MARS_MEM_MAX_RESERVE
+	bool "avoid memory fragmentation by preallocation"
+	depends on MARS_MEM_PREALLOC
+	default n
+	help
+	Higher preallocation reserve, for avoidance of
+	too frequent higher-order memory allocations on
+	highly loaded servers with a lot of resources.
+	May be enabled when encountering suchalike problems
+	(known as accurring very rare, but may happen).
+
 config MARS_FAST_FULLSYNC
 	bool "decrease network traffic at initial sync"
 	depends on MARS

kernel/brick_mem.c

@@ -735,6 +735,22 @@ int brick_mem_reserve(void)
 #endif
 EXPORT_SYMBOL_GPL(brick_mem_reserve);
 
+#ifdef CONFIG_MARS_MEM_MAX_RESERVE
+void set_brick_mem_freelist_max(int max, int order)
+{
+	if (max > brick_mem_freelist_max[order]) {
+		brick_mem_freelist_max[order] = max;
+	} else if (max < brick_mem_freelist_max[order] / 2 &&
+		   brick_mem_freelist_max[order] > 0) {
+		brick_mem_freelist_max[order]--;
+	}
+}
+#else
+void set_brick_mem_freelist_max(int max, int order)
+{
+}
+#endif
+
 void *_brick_block_alloc(loff_t pos, int len, int line)
 {
 	void *data;

kernel/brick_mem.h

@@ -244,6 +244,7 @@ extern int brick_mem_alloc_count[BRICK_MAX_ORDER+1];
 extern int brick_mem_alloc_max[BRICK_MAX_ORDER+1];
 
 extern int brick_mem_reserve(void);
+extern void set_brick_mem_freelist_max(int max, int order);
 
 #endif
 

kernel/sy_old/mars_main.c

@@ -247,12 +247,30 @@ void _crashme(int mode, bool do_sync)
 		emergency_restart();
 	}
 }
-
 #endif
 
+#define MARS_MEMRESERVE_ORDER		 5
+#define MEMRESERVE_FACTOR_5		32
+
 int nr_affected_resources;
 int tmp_nr_affected_resources;
 
+void update_brick_mem_freelist_max(void)
+{
+#ifdef CONFIG_MARS_MEM_MAX_RESERVE
+	int order;
+
+	for (order = 0; order <= BRICK_MAX_ORDER; order++) {
+		int max = 0;
+
+		if (order == MARS_MEMRESERVE_ORDER) {
+			max = nr_affected_resources * MEMRESERVE_FACTOR_5;
+		}
+		set_brick_mem_freelist_max(max, order);
+	}
+#endif
+}
+
 void invalidate_user_cache(void)
 {
 	const char *path;
@@ -7903,6 +7921,8 @@ static int _main_thread(void *data)
 
 		__make_alivelink("compat-alivelinks", compat_alivelinks, true);
 
+		update_brick_mem_freelist_max();
+
 		down_read(&rot_sem);
 		for (tmp = rot_anchor.next; tmp != &rot_anchor; tmp = tmp->next) {
 			struct mars_rotate *rot = container_of(tmp, struct mars_rotate, rot_head);
@@ -8213,7 +8233,7 @@ static int __init init_main(void)
 	DO_INIT(mars_proc);
 
 #ifdef CONFIG_MARS_MEM_PREALLOC
-	brick_pre_reserve[5] = 64;
+	brick_pre_reserve[MARS_MEMRESERVE_ORDER] = 64;
 	brick_mem_reserve();
 #endif