From: Zhi Yong Wu <wu...@linux.vnet.ibm.com>

  Add a per-superblock workqueue and a delayed_work
to run periodic work to update map info on each superblock.

Signed-off-by: Zhi Yong Wu <wu...@linux.vnet.ibm.com>
---
 fs/hot_tracking.c            |   85 ++++++++++++++++++++++++++++++++++++++++++
 fs/hot_tracking.h            |    3 +
 include/linux/hot_tracking.h |    3 +
 3 files changed, 91 insertions(+), 0 deletions(-)

diff --git a/fs/hot_tracking.c b/fs/hot_tracking.c
index e85eaa6..552bee0 100644
--- a/fs/hot_tracking.c
+++ b/fs/hot_tracking.c
@@ -15,9 +15,12 @@
 #include <linux/module.h>
 #include <linux/spinlock.h>
 #include <linux/hardirq.h>
+#include <linux/kthread.h>
+#include <linux/freezer.h>
 #include <linux/fs.h>
 #include <linux/blkdev.h>
 #include <linux/types.h>
+#include <linux/list_sort.h>
 #include <linux/limits.h>
 #include "hot_tracking.h"
 
@@ -553,6 +556,67 @@ static void hot_map_exit(struct hot_info *root)
        }
 }
 
+/* Temperature compare function*/
+static int hot_temp_cmp(void *priv, struct list_head *a,
+                               struct list_head *b)
+{
+       struct hot_comm_item *ap =
+                       container_of(a, struct hot_comm_item, n_list);
+       struct hot_comm_item *bp =
+                       container_of(b, struct hot_comm_item, n_list);
+
+       int diff = ap->hot_freq_data.last_temp
+                               - bp->hot_freq_data.last_temp;
+       if (diff > 0)
+               return -1;
+       if (diff < 0)
+               return 1;
+       return 0;
+}
+
+/*
+ * Every sync period we update temperatures for
+ * each hot inode item and hot range item for aging
+ * purposes.
+ */
+static void hot_update_worker(struct work_struct *work)
+{
+       struct hot_info *root = container_of(to_delayed_work(work),
+                                       struct hot_info, update_work);
+       struct hot_inode_item *hi_nodes[8];
+       unsigned long ino = 0;
+       int i, n;
+
+       while (1) {
+               n = radix_tree_gang_lookup(&root->hot_inode_tree,
+                                  (void **)hi_nodes, ino,
+                                  ARRAY_SIZE(hi_nodes));
+               if (!n)
+                       break;
+
+               ino = hi_nodes[n - 1]->i_ino + 1;
+               for (i = 0; i < n; i++) {
+                       kref_get(&hi_nodes[i]->hot_inode.refs);
+                       hot_map_update(
+                               &hi_nodes[i]->hot_inode.hot_freq_data, root);
+                       hot_range_update(hi_nodes[i], root);
+                       hot_inode_item_put(hi_nodes[i]);
+               }
+       }
+
+       /* Sort temperature map info */
+       for (i = 0; i < HEAT_MAP_SIZE; i++) {
+               list_sort(NULL, &root->heat_inode_map[i].node_list,
+                       hot_temp_cmp);
+               list_sort(NULL, &root->heat_range_map[i].node_list,
+                       hot_temp_cmp);
+       }
+
+       /* Instert next delayed work */
+       queue_delayed_work(root->update_wq, &root->update_work,
+               msecs_to_jiffies(HEAT_UPDATE_DELAY * MSEC_PER_SEC));
+}
+
 /*
  * Initialize kmem cache for hot_inode_item and hot_range_item.
  */
@@ -647,9 +711,28 @@ int hot_track_init(struct super_block *sb)
        hot_inode_tree_init(root);
        hot_map_init(root);
 
+       root->update_wq = alloc_workqueue(
+               "hot_update_wq", WQ_NON_REENTRANT, 0);
+       if (!root->update_wq) {
+               printk(KERN_ERR "%s: Failed to create "
+                               "hot update workqueue\n", __func__);
+               goto failed_wq;
+       }
+
+       /* Initialize hot tracking wq and arm one delayed work */
+       INIT_DELAYED_WORK(&root->update_work, hot_update_worker);
+       queue_delayed_work(root->update_wq, &root->update_work,
+               msecs_to_jiffies(HEAT_UPDATE_DELAY * MSEC_PER_SEC));
+
        printk(KERN_INFO "VFS: Turning on hot data tracking\n");
 
        return 0;
+
+failed_wq:
+       hot_map_exit(root);
+       hot_inode_tree_exit(root);
+       kfree(root);
+       return ret;
 }
 EXPORT_SYMBOL_GPL(hot_track_init);
 
@@ -657,6 +740,8 @@ void hot_track_exit(struct super_block *sb)
 {
        struct hot_info *root = sb->s_hot_root;
 
+       cancel_delayed_work_sync(&root->update_work);
+       destroy_workqueue(root->update_wq);
        hot_map_exit(root);
        hot_inode_tree_exit(root);
        kfree(root);
diff --git a/fs/hot_tracking.h b/fs/hot_tracking.h
index 0d28e6f..6dbd27a 100644
--- a/fs/hot_tracking.h
+++ b/fs/hot_tracking.h
@@ -31,6 +31,9 @@
  */
 #define TIME_TO_KICK 300
 
+/* set how often to update temperatures (seconds) */
+#define HEAT_UPDATE_DELAY 300
+
 /* NRR/NRW heat unit = 2^X accesses */
 #define NRR_MULTIPLIER_POWER 20 /* NRR - number of reads since mount */
 #define NRR_COEFF_POWER 0
diff --git a/include/linux/hot_tracking.h b/include/linux/hot_tracking.h
index 5227e89..af49078 100644
--- a/include/linux/hot_tracking.h
+++ b/include/linux/hot_tracking.h
@@ -82,6 +82,9 @@ struct hot_info {
        /* map of range temperature */
        struct hot_map_head heat_range_map[HEAT_MAP_SIZE];
        unsigned int hot_map_nr;
+
+       struct workqueue_struct *update_wq;
+       struct delayed_work update_work;
 };
 
 extern void __init hot_cache_init(void);
-- 
1.7.6.5

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