Re: [PATCH 3/3] plist: shrink plist_head

[Lai Jiangshan]

On 12/16/2010 06:23 PM, Lai Jiangshan wrote:
> struct plist_head is too big, and the field prio_list
> in the struct plist_head is used seldom. So it can be
> removed and we use the first plist_node's prio_list
> when needed.
> 
> The size of struct rtmutex and struct task_struct will
> also decreased after struct plist_head shrinked.
> 
> Signed-off-by:  Lai Jiangshan <laijs@xxxxxxxxxxxxxx>
> ---
>  include/linux/plist.h |   47 ++++++++++++++++++++++---------------------
>  lib/plist.c           |   54 ++++++++++++++++++++++++++++++++------------------
>  2 files changed, 59 insertions(+), 42 deletions(-)
> 
> diff --git a/include/linux/plist.h b/include/linux/plist.h
> index 7254eda..c9b9f32 100644
> --- a/include/linux/plist.h
> +++ b/include/linux/plist.h
> @@ -31,15 +31,17 @@
>   *
>   * Simple ASCII art explanation:
>   *
> - * |HEAD          |
> - * |              |
> - * |prio_list.prev|<------------------------------------|
> - * |prio_list.next|<->|pl|<->|pl|<--------------->|pl|<-|
> - * |10            |   |10|   |21|   |21|   |21|   |40|   (prio)
> - * |              |   |  |   |  |   |  |   |  |   |  |
> - * |              |   |  |   |  |   |  |   |  |   |  |
> - * |node_list.next|<->|nl|<->|nl|<->|nl|<->|nl|<->|nl|<-|
> - * |node_list.prev|<------------------------------------|
> + * pl:prio_list (only for plist_node)
> + * nl:node_list
> + *   HEAD|             NODE(S)
> + *       |
> + *       ||------------------------------------|
> + *       ||->|pl|<->|pl|<--------------->|pl|<-|
> + *       |   |10|   |21|   |21|   |21|   |40|   (prio)
> + *       |   |  |   |  |   |  |   |  |   |  |
> + *       |   |  |   |  |   |  |   |  |   |  |
> + * |->|nl|<->|nl|<->|nl|<->|nl|<->|nl|<->|nl|<-|
> + * |-------------------------------------------|
>   *

This is the test code for this new plist.
After my careful review and the tests, I trust this plist.

Subject: [PATCH] plist: test for plist

Add test code for checking plist when kernel is booting.

Signed-off-by:  Lai Jiangshan <laijs@xxxxxxxxxxxxxx>
---
diff --git a/lib/plist.c b/lib/plist.c
index 8c614d0..0ae7e64 100644
--- a/lib/plist.c
+++ b/lib/plist.c
@@ -28,6 +28,8 @@
 
 #ifdef CONFIG_DEBUG_PI_LIST
 
+static struct plist_head test_head;
+
 static void plist_check_prev_next(struct list_head *t, struct list_head *p,
 				  struct list_head *n)
 {
@@ -54,7 +56,7 @@ static void plist_check_list(struct list_head *top)
 
 static void plist_check_head(struct plist_head *head)
 {
-	WARN_ON(!head->rawlock && !head->spinlock);
+	WARN_ON(head != &test_head && !head->rawlock && !head->spinlock);
 	if (head->rawlock)
 		WARN_ON_SMP(!raw_spin_is_locked(head->rawlock));
 	if (head->spinlock)
@@ -135,3 +137,80 @@ void plist_del(struct plist_node *node, struct plist_head *head)
 
 	plist_check_head(head);
 }
+
+#ifdef CONFIG_DEBUG_PI_LIST
+#include <linux/sched.h>
+#include <linux/module.h>
+#include <linux/init.h>
+
+static struct plist_node __initdata test_node[241];
+
+static void __init plist_test_check(int nr_expect)
+{
+	struct plist_node *first, *prio_pos, *node_pos;
+
+	if (plist_head_empty(&test_head)) {
+		BUG_ON(nr_expect != 0);
+		return;
+	}
+
+	prio_pos = first = plist_first(&test_head);
+	plist_for_each(node_pos, &test_head) {
+		if (nr_expect-- < 0)
+			break;
+		if (node_pos == first)
+			continue;
+		if (node_pos->prio == prio_pos->prio) {
+			BUG_ON(!list_empty(&node_pos->prio_list));
+			continue;
+		}
+
+		BUG_ON(prio_pos->prio > node_pos->prio);
+		BUG_ON(prio_pos->prio_list.next != &node_pos->prio_list);
+		prio_pos = node_pos;
+	}
+
+	BUG_ON(nr_expect != 0);
+	BUG_ON(prio_pos->prio_list.next != &first->prio_list);
+}
+
+static int  __init plist_test(void)
+{
+	int nr_expect = 0, i, loop;
+	unsigned int r = local_clock();
+
+	printk(KERN_INFO "start plist test\n");
+	plist_head_init(&test_head, NULL);
+	for (i = 0; i < ARRAY_SIZE(test_node); i++)
+		plist_node_init(test_node + i, 0);
+
+	for (loop = 0; loop < 1000; loop++) {
+		r = r * 193939 % 47629;
+		i = r % ARRAY_SIZE(test_node);
+		if (plist_node_empty(test_node + i)) {
+			r = r * 193939 % 47629;
+			test_node[i].prio = r % 99;
+			plist_add(test_node + i, &test_head);
+			nr_expect++;
+		} else {
+			plist_del(test_node + i, &test_head);
+			nr_expect--;
+		}
+		plist_test_check(nr_expect);
+	}
+
+	for (i = 0; i < ARRAY_SIZE(test_node); i++) {
+		if (plist_node_empty(test_node + i))
+			continue;
+		plist_del(test_node + i, &test_head);
+		nr_expect--;
+		plist_test_check(nr_expect);
+	}
+
+	printk(KERN_INFO "end plist test\n");
+	return 0;
+}
+
+module_init(plist_test);
+
+#endif
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