[PATCH v19 08/40] dept: add a mechanism to refill the internal memory pools on running out

@@ -75,6 +75,9 @@
 #include <linux/dept.h>
 #include <linux/utsname.h>
 #include <linux/kernel.h>
+#include <linux/workqueue.h>
+#include <linux/irq_work.h>
+#include <linux/vmalloc.h>
 #include "dept_internal.h"
 
 static int dept_stop;

@@ -143,9 +146,11 @@ static inline struct dept_task *dept_task(void)
 		}							\
 	})
 
-#define DEPT_INFO_ONCE(s...) pr_warn_once("DEPT_INFO_ONCE: " s)
+#define DEPT_INFO_ONCE(s...)	pr_warn_once("DEPT_INFO_ONCE: " s)
+#define DEPT_INFO(s...)		pr_warn("DEPT_INFO: " s)
 
 static arch_spinlock_t dept_spin = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
+static arch_spinlock_t dept_pool_spin = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
 
 /*
  * The DEPT internal engine should be cautious when using external functions

@@ -268,6 +273,7 @@ static bool valid_key(struct dept_key *k)
 
 #define OBJECT(id, nr)							\
 static struct dept_##id spool_##id[nr];					\
+static struct dept_##id rpool_##id[nr];					\
 static DEFINE_PER_CPU(struct llist_head, lpool_##id);
 	#include "dept_object.h"
 #undef OBJECT

@@ -276,14 +282,74 @@ struct dept_pool dept_pool[OBJECT_NR] = {
 #define OBJECT(id, nr) {						\
 	.name = #id,							\
 	.obj_sz = sizeof(struct dept_##id),				\
-	.obj_nr = ATOMIC_INIT(nr),					\
+	.obj_nr = nr,							\
+	.tot_nr = nr,							\
+	.acc_sz = ATOMIC_INIT(sizeof(spool_##id) + sizeof(rpool_##id)), \
 	.node_off = offsetof(struct dept_##id, pool_node),		\
 	.spool = spool_##id,						\
+	.rpool = rpool_##id,						\
 	.lpool = &lpool_##id, },
 	#include "dept_object.h"
 #undef OBJECT
 };
 
+static void dept_wq_work_fn(struct work_struct *work)
+{
+	int i;
+
+	for (i = 0; i < OBJECT_NR; i++) {
+		struct dept_pool *p = dept_pool + i;
+		int sz = p->tot_nr * p->obj_sz;
+		void *rpool;
+		bool need;
+
+		local_irq_disable();
+		arch_spin_lock(&dept_pool_spin);
+		need = !p->rpool;
+		arch_spin_unlock(&dept_pool_spin);
+		local_irq_enable();
+
+		if (!need)
+			continue;
+
+		rpool = vmalloc(sz);
+
+		if (!rpool) {
+			DEPT_STOP("Failed to extend internal resources.\n");
+			break;
+		}
+
+		local_irq_disable();
+		arch_spin_lock(&dept_pool_spin);
+		if (!p->rpool) {
+			p->rpool = rpool;
+			rpool = NULL;
+			atomic_add(sz, &p->acc_sz);
+		}
+		arch_spin_unlock(&dept_pool_spin);
+		local_irq_enable();
+
+		if (rpool)
+			vfree(rpool);
+		else
+			DEPT_INFO("Dept object(%s) just got refilled successfully.\n", p->name);
+	}
+}
+
+static DECLARE_WORK(dept_wq_work, dept_wq_work_fn);
+
+static void dept_irq_work_fn(struct irq_work *w)
+{
+	schedule_work(&dept_wq_work);
+}
+
+static DEFINE_IRQ_WORK(dept_irq_work, dept_irq_work_fn);
+
+static void request_rpool_refill(void)
+{
+	irq_work_queue(&dept_irq_work);
+}
+
 /*
  * We can use llist regardless of whether CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
  * is enabled, because NMI and other contexts on the same CPU never run

@@ -319,19 +385,31 @@ static void *from_pool(enum object_t t)
 	/*
 	 * Try static pool.
 	 */
-	if (atomic_read(&p->obj_nr) > 0) {
-		int idx = atomic_dec_return(&p->obj_nr);
+	arch_spin_lock(&dept_pool_spin);
+
+	if (!p->obj_nr) {
+		p->spool = p->rpool;
+		p->obj_nr = p->rpool ? p->tot_nr : 0;
+		p->rpool = NULL;
+		request_rpool_refill();
+	}
+
+	if (p->obj_nr) {
+		void *ret;
+
+		p->obj_nr--;
+		ret = p->spool + (p->obj_nr * p->obj_sz);
+		arch_spin_unlock(&dept_pool_spin);
 
-		if (idx >= 0)
-			return p->spool + (idx * p->obj_sz);
+		return ret;
 	}
+	arch_spin_unlock(&dept_pool_spin);
 
-	DEPT_INFO_ONCE("---------------------------------------------\n"
-		"  Some of Dept internal resources are run out.\n"
-		"  Dept might still work if the resources get freed.\n"
-		"  However, the chances are Dept will suffer from\n"
-		"  the lack from now. Needs to extend the internal\n"
-		"  resource pools. Ask max.byungchul.park@gmail.com\n");
+	DEPT_INFO("------------------------------------------\n"
+		"  Dept object(%s) is run out.\n"
+		"  Dept is trying to refill the object.\n"
+		"  Nevertheless, if it fails, Dept will stop.\n",
+		p->name);
 	return NULL;
 }
 

@@ -2957,8 +3035,8 @@ void __init dept_init(void)
 	pr_info("... DEPT_MAX_ECXT_HELD  : %d\n", DEPT_MAX_ECXT_HELD);
 	pr_info("... DEPT_MAX_SUBCLASSES : %d\n", DEPT_MAX_SUBCLASSES);
 #define OBJECT(id, nr)							\
-	pr_info("... memory used by %s: %zu KB\n",			\
-	       #id, B2KB(sizeof(struct dept_##id) * nr));
+	pr_info("... memory initially used by %s: %zu KB\n",		\
+	       #id, B2KB(sizeof(spool_##id) + sizeof(rpool_##id)));
 	#include "dept_object.h"
 #undef OBJECT
 #define HASH(id, bits)							\

@@ -2966,6 +3044,6 @@ void __init dept_init(void)
 	       #id, B2KB(sizeof(struct hlist_head) * (1 << (bits))));
 	#include "dept_hash.h"
 #undef HASH
-	pr_info("... total memory used by objects and hashs: %zu KB\n", B2KB(mem_total));
+	pr_info("... total memory initially used by objects and hashs: %zu KB\n", B2KB(mem_total));
 	pr_info("... per task memory footprint: %zu bytes\n", sizeof(struct dept_task));
 }

@@ -26,9 +26,19 @@ struct dept_pool {
 	size_t				obj_sz;
 
 	/*
-	 * the number of the static array
+	 * the remaining number of the object in spool
 	 */
-	atomic_t			obj_nr;
+	int				obj_nr;
+
+	/*
+	 * the number of the object in spool
+	 */
+	int				tot_nr;
+
+	/*
+	 * accumulated amount of memory used by the object in byte
+	 */
+	atomic_t			acc_sz;
 
 	/*
 	 * offset of ->pool_node

@@ -38,9 +48,10 @@ struct dept_pool {
 	/*
 	 * pointer to the pool
 	 */
-	void				*spool;
+	void				*spool; /* static pool */
+	void				*rpool; /* reserved pool */
 	struct llist_head		boot_pool;
-	struct llist_head __percpu	*lpool;
+	struct llist_head __percpu	*lpool; /* local pool */
 };
 
 struct dept_ecxt;

@@ -6,8 +6,8 @@
  * nr: # of the object that should be kept in the pool.
  */
 
-OBJECT(dep, 1024 * 8)
-OBJECT(class, 1024 * 8)
-OBJECT(stack, 1024 * 32)
-OBJECT(ecxt, 1024 * 16)
-OBJECT(wait, 1024 * 32)
+OBJECT(dep, 1024 * 4 * 2)
+OBJECT(class, 1024 * 4)
+OBJECT(stack, 1024 * 4 * 8)
+OBJECT(ecxt, 1024 * 4 * 2)
+OBJECT(wait, 1024 * 4 * 4)

@@ -74,12 +74,10 @@ static int dept_stats_show(struct seq_file *m, void *v)
 {
 	int r;
 
-	seq_puts(m, "Availability in the static pools:\n\n");
+	seq_puts(m, "Accumulated amount of memory used by pools:\n\n");
 #define OBJECT(id, nr)							\
-	r = atomic_read(&dept_pool[OBJECT_##id].obj_nr);		\
-	if (r < 0)							\
-		r = 0;							\
-	seq_printf(m, "%s\t%d/%d(%d%%)\n", #id, r, nr, (r * 100) / (nr));
+	r = atomic_read(&dept_pool[OBJECT_##id].acc_sz);		\
+	seq_printf(m, "%s\t%d KB\n", #id, r / 1024);
 	#include "dept_object.h"
 #undef  OBJECT