VFS hot tracking

index f09b908..9d7c2af 100644
@@ -37,6 +37,7 @@
 #include <linux/rculist_bl.h>
 #include <linux/prefetch.h>
 #include <linux/ratelimit.h>
+#include <linux/hot_tracking.h>
 #include "internal.h"
 #include "mount.h"
 

@@ -3094,4 +3095,5 @@ void __init vfs_caches_init(unsigned long mempages)
 	mnt_init();
 	bdev_cache_init();
 	chrdev_init();
+	hot_cache_init();
 }

209 lines not on this page · raw message

new file mode 100644
index 0000000..a2ee95f
@@ -0,0 +1,17 @@
+/*
+ * fs/hot_tracking.h
+ *
+ * Copyright (C) 2013 IBM Corp. All rights reserved.
+ * Written by Zhi Yong Wu <[email protected]>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License v2 as published by the Free Software Foundation.
+ */
+
+#ifndef __HOT_TRACKING__
+#define __HOT_TRACKING__
+
+#include <linux/hot_tracking.h>
+
+#endif /* __HOT_TRACKING__ */

index 43db02e..ee2c54f 100644
@@ -27,6 +27,7 @@
 #include <linux/lockdep.h>
 #include <linux/percpu-rwsem.h>
 #include <linux/blk_types.h>
+#include <linux/hot_tracking.h>
 
 #include <asm/byteorder.h>
 #include <uapi/linux/fs.h>

@@ -1322,6 +1323,9 @@ struct super_block {
 
 	/* Being remounted read-only */
 	int s_readonly_remount;
+
+	/* Hot data tracking*/
+	struct hot_info *s_hot_root;
 };
 
 /* superblock cache pruning functions */

103 lines not on this page · raw message

index 7ab90f5..6cb0598 100644
@@ -38,6 +38,7 @@
 #include <linux/atomic.h>
 #include <linux/prefetch.h>
 #include <linux/aio.h>
+#include "hot_tracking.h"
 
 /*
  * How many user pages to map in one call to get_user_pages().  This determines

@@ -1295,6 +1296,10 @@ __blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,
 	prefetch(bdev->bd_queue);
 	prefetch((char *)bdev->bd_queue + SMP_CACHE_BYTES);
 
+	/* Hot data tracking */
+	hot_update_freqs(inode, offset, iov_length(iov, nr_segs),
+			rw & WRITE);
+
 	return do_blockdev_direct_IO(rw, iocb, inode, bdev, iov, offset,
 				     nr_segs, get_block, end_io,
 				     submit_io, flags);

318 lines not on this page · raw message

index a2ee95f..bb4cb16 100644
@@ -14,4 +14,8 @@
 
 #include <linux/hot_tracking.h>
 
+/* size of sub-file ranges */
+#define RANGE_BITS 20
+#define FREQ_POWER 4
+
 #endif /* __HOT_TRACKING__ */

index 85e40d1..2eec542 100644
@@ -3394,6 +3394,8 @@ int vfs_unlink(struct inode *dir, struct dentry *dentry)
 	if (!dir->i_op->unlink)
 		return -EPERM;
 
+	hot_inode_item_delete(dentry->d_inode);
+
 	mutex_lock(&dentry->d_inode->i_mutex);
 	if (d_mountpoint(dentry))
 		error = -EBUSY;

index fa99439..3c0cf57 100644
@@ -67,6 +67,8 @@ struct hot_inode_item {
 	struct hot_comm_item hot_inode; /* node in hot_inode_tree */
 	struct rb_root hot_range_tree;	/* tree of ranges */
 	spinlock_t i_lock;		/* protect above tree */
+	struct hot_info *hot_root;	/* associated hot_info */
+	u64 i_ino;			/* inode number from inode */
 };
 
 /*

@@ -76,6 +78,9 @@ struct hot_inode_item {
 struct hot_range_item {
 	struct hot_comm_item hot_range;
 	struct hot_inode_item *hot_inode;	/* associated hot_inode_item */
+	loff_t start;				/* offset in bytes */
+	size_t len;				/* length in bytes */
+	int storage_type;			/* type of storage */
 };
 
 struct hot_info {

@@ -89,6 +94,13 @@ extern void __init hot_cache_init(void);
 extern int hot_track_init(struct super_block *sb);
 extern void hot_track_exit(struct super_block *sb);
 extern void hot_comm_item_put(struct hot_comm_item *ci);
+extern void hot_update_freqs(struct inode *inode, loff_t start,
+				size_t len, int rw);
+extern struct hot_inode_item *hot_inode_item_lookup(struct hot_info *root,
+						u64 ino, int alloc);
+extern struct hot_range_item *hot_range_item_lookup(struct hot_inode_item *he,
+						loff_t start, int alloc);
+extern void hot_inode_item_delete(struct inode *inode);
 
 static inline u64 hot_shift(u64 counter, u32 bits, bool dir)
 {

@@ -98,6 +110,11 @@ static inline u64 hot_shift(u64 counter, u32 bits, bool dir)
 		return counter >> bits;
 }
 
+static inline void hot_comm_item_get(struct hot_comm_item *ci)
+{
+	kref_get(&ci->refs);
+}
+
 #endif /* __KERNEL__ */
 
 #endif  /* _LINUX_HOTTRACK_H */

index 7905fe7..eb64c49 100644
@@ -33,6 +33,7 @@
 #include <linux/hardirq.h> /* for BUG_ON(!in_atomic()) only */
 #include <linux/memcontrol.h>
 #include <linux/cleancache.h>
+#include <linux/hot_tracking.h>
 #include "internal.h"
 
 #define CREATE_TRACE_POINTS

@@ -1242,6 +1243,11 @@ readpage:
 		 * PG_error will be set again if readpage fails.
 		 */
 		ClearPageError(page);
+
+		/* Hot data tracking */
+		hot_update_freqs(inode, (loff_t)page->index << PAGE_CACHE_SHIFT,
+				PAGE_CACHE_SIZE, 0);
+
 		/* Start the actual read. The read will unlock the page. */
 		error = mapping->a_ops->readpage(filp, page);
 

index 4514ad7..4bbca3a 100644
@@ -36,6 +36,7 @@
 #include <linux/pagevec.h>
 #include <linux/timer.h>
 #include <linux/sched/rt.h>
+#include <linux/hot_tracking.h>
 #include <trace/events/writeback.h>
 
 /*

@@ -1921,13 +1922,24 @@ EXPORT_SYMBOL(generic_writepages);
 int do_writepages(struct address_space *mapping, struct writeback_control *wbc)
 {
 	int ret;
+	loff_t start = 0;
+	size_t count = 0;
 
 	if (wbc->nr_to_write <= 0)
 		return 0;
+
+	start = mapping->writeback_index << PAGE_CACHE_SHIFT;
+	count = wbc->nr_to_write;
+
 	if (mapping->a_ops->writepages)
 		ret = mapping->a_ops->writepages(mapping, wbc);
 	else
 		ret = generic_writepages(mapping, wbc);
+
+	/* Hot data tracking */
+	hot_update_freqs(mapping->host, start,
+			(count - wbc->nr_to_write) * PAGE_CACHE_SIZE, 1);
+
 	return ret;
 }
 

index daed28d..901396b 100644
@@ -19,6 +19,7 @@
 #include <linux/pagemap.h>
 #include <linux/syscalls.h>
 #include <linux/file.h>
+#include <linux/hot_tracking.h>
 
 /*
  * Initialise a struct file's readahead state.  Assumes that the caller has

@@ -115,6 +116,11 @@ static int read_pages(struct address_space *mapping, struct file *filp,
 	unsigned page_idx;
 	int ret;
 
+	/* Hot data tracking */
+	hot_update_freqs(mapping->host,
+			list_to_page(pages)->index << PAGE_CACHE_SHIFT,
+			(size_t)nr_pages * PAGE_CACHE_SIZE, 0);
+
 	blk_start_plug(&plug);
 
 	if (mapping->a_ops->readpages) {

index cc899f4..2742d9e 100644
@@ -29,7 +29,9 @@ static void hot_inode_item_free(struct kref *kref);
 static void hot_comm_item_init(struct hot_comm_item *ci, int type)
 {
 	kref_init(&ci->refs);
+	clear_bit(HOT_IN_LIST, &ci->delete_flag);
 	clear_bit(HOT_DELETING, &ci->delete_flag);
+	INIT_LIST_HEAD(&ci->track_list);
 	memset(&ci->hot_freq_data, 0, sizeof(struct hot_freq_data));
 	ci->hot_freq_data.avg_delta_reads = (u64) -1;
 	ci->hot_freq_data.avg_delta_writes = (u64) -1;

@@ -86,12 +88,21 @@ void hot_comm_item_put(struct hot_comm_item *ci)
 EXPORT_SYMBOL_GPL(hot_comm_item_put);
 
 /*
- * root->t_lock or he->i_lock is acquired in this function
+ * root->t_lock or he->i_lock, and root->m_lock
+ * are acquired in this function
  */
 static void hot_comm_item_unlink(struct hot_info *root,
 				struct hot_comm_item *ci)
 {
 	if (!test_and_set_bit(HOT_DELETING, &ci->delete_flag)) {
+		if (test_and_clear_bit(HOT_IN_LIST, &ci->delete_flag)) {
+			spin_lock(&root->m_lock);
+			list_del_rcu(&ci->track_list);
+			spin_unlock(&root->m_lock);
+
+			hot_comm_item_put(ci);
+		}
+
 		if (ci->hot_freq_data.flags == TYPE_RANGE) {
 			struct hot_range_item *hr = container_of(ci,
 					struct hot_range_item, hot_range);

@@ -343,6 +354,274 @@ static void hot_freq_update(struct hot_info *root,
 }
 
 /*
+ * hot_temp_calc() is responsible for distilling the six heat
+ * criteria down into a single temperature value for the data,
+ * which is an integer between 0 and HEAT_MAX_VALUE.
+ *
+ * With the six values, we first do some very rudimentary
+ * "normalizations" to each metric such that they affect the
+ * final temperature calculation exactly the right way. It's
+ * important to note that we still weren't really sure that
+ * these six adjustments were exactly right.
+ * They could definitely use more tweaking and adjustment,
+ * especially in terms of the memory footprint they consume.
+ *
+ * Next, we take the adjusted values and shift them down to
+ * a manageable size, whereafter they are weighted using the
+ * the *_COEFF_POWER values and combined to a single temperature
+ * value.
+ */
+static u32 hot_temp_calc(struct hot_comm_item *ci)
+{
+	u32 result = 0;
+	struct hot_freq_data *freq_data = &ci->hot_freq_data;
+
+	struct timespec ckt = current_kernel_time();
+	u64 cur_time = timespec_to_ns(&ckt);
+	u32 nrr_heat, nrw_heat;
+	u64 ltr_heat, ltw_heat, avr_heat, avw_heat;
+
+	nrr_heat = (u32)hot_shift((u64)freq_data->nr_reads,
+					NRR_MULTIPLIER_POWER, true);
+	nrw_heat = (u32)hot_shift((u64)freq_data->nr_writes,
+					NRW_MULTIPLIER_POWER, true);
+
+	ltr_heat =
+	hot_shift((cur_time - timespec_to_ns(&freq_data->last_read_time)),
+			LTR_DIVIDER_POWER, false);
+	ltw_heat =
+	hot_shift((cur_time - timespec_to_ns(&freq_data->last_write_time)),
+			LTW_DIVIDER_POWER, false);
+
+	avr_heat =
+	hot_shift((((u64) -1) - freq_data->avg_delta_reads),
+			AVR_DIVIDER_POWER, false);
+	avw_heat =
+	hot_shift((((u64) -1) - freq_data->avg_delta_writes),
+			AVW_DIVIDER_POWER, false);
+
+	/* ltr_heat is now guaranteed to be u32 safe */
+	if (ltr_heat >= hot_shift((u64) 1, 32, true))
+		ltr_heat = 0;
+	else
+		ltr_heat = hot_shift((u64) 1, 32, true) - ltr_heat;
+
+	/* ltw_heat is now guaranteed to be u32 safe */
+	if (ltw_heat >= hot_shift((u64) 1, 32, true))
+		ltw_heat = 0;
+	else
+		ltw_heat = hot_shift((u64) 1, 32, true) - ltw_heat;
+
+	/* avr_heat is now guaranteed to be u32 safe */
+	if (avr_heat >= hot_shift((u64) 1, 32, true))
+		avr_heat = (u32) -1;
+
+	/* avw_heat is now guaranteed to be u32 safe */
+	if (avw_heat >= hot_shift((u64) 1, 32, true))
+		avw_heat = (u32) -1;
+
+	nrr_heat = (u32)hot_shift((u64)nrr_heat,
+		(3 - NRR_COEFF_POWER), false);
+	nrw_heat = (u32)hot_shift((u64)nrw_heat,
+		(3 - NRW_COEFF_POWER), false);
+	ltr_heat = hot_shift(ltr_heat, (3 - LTR_COEFF_POWER), false);
+	ltw_heat = hot_shift(ltw_heat, (3 - LTW_COEFF_POWER), false);
+	avr_heat = hot_shift(avr_heat, (3 - AVR_COEFF_POWER), false);
+	avw_heat = hot_shift(avw_heat, (3 - AVW_COEFF_POWER), false);
+
+	result = nrr_heat + nrw_heat + (u32) ltr_heat +
+		(u32) ltw_heat + (u32) avr_heat + (u32) avw_heat;
+
+	return result;
+}
+
+static bool hot_is_obsolete(struct hot_comm_item *ci)
+{
+	int ret = 0;
+	struct timespec ckt = current_kernel_time();
+	struct hot_freq_data *freq_data = &ci->hot_freq_data;
+	u64 last_read_ns, last_write_ns;
+	u64 cur_time = timespec_to_ns(&ckt);
+	u64 kick_ns =  HOT_AGE_INTERVAL * NSEC_PER_SEC;
+
+	last_read_ns =
+		(cur_time - timespec_to_ns(&freq_data->last_read_time));
+	last_write_ns =
+		(cur_time - timespec_to_ns(&freq_data->last_write_time));
+
+	if ((last_read_ns > kick_ns) && (last_write_ns > kick_ns))
+		ret = 1;
+
+	return ret;
+}
+
+static void hot_comm_item_link_cb(struct rcu_head *head)
+{
+	struct hot_comm_item *ci = container_of(head,
+				struct hot_comm_item, c_rcu);
+	struct hot_info *root;
+	u32 cur_temp = ci->hot_freq_data.last_temp;
+
+	if (ci->hot_freq_data.flags == TYPE_RANGE) {
+		struct hot_range_item *hr = container_of(ci,
+				struct hot_range_item, hot_range);
+		root = hr->hot_inode->hot_root;
+	} else {
+		struct hot_inode_item *he = container_of(ci,
+				struct hot_inode_item, hot_inode);
+		root = he->hot_root;
+
+	}
+
+	spin_lock(&root->m_lock);
+	if (test_bit(HOT_DELETING, &ci->delete_flag)) {
+		spin_unlock(&root->m_lock);
+		return;
+	}
+	list_add_tail_rcu(&ci->track_list,
+		&root->hot_map[ci->hot_freq_data.flags][cur_temp]);
+	spin_unlock(&root->m_lock);
+}
+
+/*
+ * Calculate a new temperature and, if necessary,
+ * move the list_head corresponding to this inode or range
+ * to the proper list with the new temperature.
+ */
+static int hot_map_update(struct hot_info *root,
+			struct hot_comm_item *ci)
+{
+	u32 temp = hot_temp_calc(ci);
+	u8 cur_temp, prev_temp;
+	int flag = false;
+
+	cur_temp = (u8)hot_shift((u64)temp,
+				(32 - MAP_BITS), false);
+	prev_temp = (u8)hot_shift((u64)ci->hot_freq_data.last_temp,
+				(32 - MAP_BITS), false);
+
+	if (cur_temp != prev_temp) {
+		if (test_and_set_bit(HOT_IN_LIST, &ci->delete_flag)) {
+			spin_lock(&root->m_lock);
+			list_del_rcu(&ci->track_list);
+			spin_unlock(&root->m_lock);
+			flag = true;
+		}
+
+		ci->hot_freq_data.last_temp = temp;
+
+		if (flag)
+			call_rcu(&ci->c_rcu, hot_comm_item_link_cb);
+			if (test_bit(HOT_DELETING, &ci->delete_flag))
+				return 1;
+		else {
+			u32 flags = ci->hot_freq_data.flags;
+
+			hot_comm_item_get(ci);
+
+			spin_lock(&root->m_lock);
+			if (test_bit(HOT_DELETING, &ci->delete_flag)) {
+				spin_unlock(&root->m_lock);
+				return 1;
+			}
+			list_add_tail_rcu(&ci->track_list,
+					&root->hot_map[flags][cur_temp]);
+			spin_unlock(&root->m_lock);
+		}
+	}
+
+	return 0;
+}
+
+/*
+ * Update temperatures for each range item for aging purposes.
+ * If one hot range item is old, it will be aged out.
+ */
+static void hot_range_update(struct hot_inode_item *he,
+				struct hot_info *root)
+{
+	struct rb_node *node;
+	struct hot_comm_item *ci;
+	bool obsolete;
+
+	rcu_read_lock();
+	node = rb_first(&he->hot_range_tree);
+	while (node) {
+		ci = rb_entry(node, struct hot_comm_item, rb_node);
+		node = rb_next(node);
+		if (test_bit(HOT_DELETING, &ci->delete_flag) ||
+			hot_map_update(root, ci)) {
+			continue;
+		}
+		obsolete = hot_is_obsolete(ci);
+		if (obsolete)
+			hot_comm_item_unlink(root, ci);
+	}
+	rcu_read_unlock();
+}
+
+/* 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, track_list);
+	struct hot_comm_item *bp = container_of(b,
+			struct hot_comm_item, track_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 rb_node *node;
+	struct hot_comm_item *ci;
+	struct hot_inode_item *he;
+	int i, j;
+
+	rcu_read_lock();
+	node = rb_first(&root->hot_inode_tree);
+	while (node) {
+		ci = rb_entry(node, struct hot_comm_item, rb_node);
+		node = rb_next(node);
+		if (test_bit(HOT_DELETING, &ci->delete_flag) ||
+			hot_map_update(root, ci)) {
+			continue;
+		}
+		he = container_of(ci,
+			struct hot_inode_item, hot_inode);
+		hot_range_update(he, root);
+	}
+	rcu_read_unlock();
+
+	/* Sort temperature map info based on last temperature*/
+	for (i = 0; i < MAP_SIZE; i++) {
+		for (j = 0; j < MAX_TYPES; j++) {
+			spin_lock(&root->m_lock);
+			list_sort(NULL, &root->hot_map[j][i], hot_temp_cmp);
+			spin_unlock(&root->m_lock);
+		}
+	}
+
+	/* Instert next delayed work */
+	queue_delayed_work(root->update_wq, &root->update_work,
+		msecs_to_jiffies(HOT_UPDATE_INTERVAL * MSEC_PER_SEC));
+}
+
+/*
  * Initialize kmem cache for hot_inode_item and hot_range_item.
  */
 void __init hot_cache_init(void)

@@ -433,6 +712,20 @@ static struct hot_info *hot_tree_init(struct super_block *sb)
 			INIT_LIST_HEAD(&root->hot_map[j][i]);
 	}
 
+	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__);
+		kfree(root);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	/* 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(HOT_UPDATE_INTERVAL * MSEC_PER_SEC));
+
 	return root;
 }
 

@@ -444,6 +737,9 @@ static void hot_tree_exit(struct hot_info *root)
 	struct rb_node *node;
 	struct hot_comm_item *ci;
 
+	cancel_delayed_work_sync(&root->update_work);
+	destroy_workqueue(root->update_wq);
+
 	rcu_read_lock();
 	node = rb_first(&root->hot_inode_tree);
 	while (node) {

index bb4cb16..8a53c2d 100644
@@ -12,10 +12,35 @@
 #ifndef __HOT_TRACKING__
 #define __HOT_TRACKING__
 
+#include <linux/workqueue.h>
 #include <linux/hot_tracking.h>
 
+#define HOT_UPDATE_INTERVAL 150
+#define HOT_AGE_INTERVAL 300
+
 /* size of sub-file ranges */
 #define RANGE_BITS 20
 #define FREQ_POWER 4
 
+/* NRR/NRW heat unit = 2^X accesses */
+#define NRR_MULTIPLIER_POWER 20 /* NRR - number of reads since mount */
+#define NRR_COEFF_POWER 0
+#define NRW_MULTIPLIER_POWER 20 /* NRW - number of writes since mount */
+#define NRW_COEFF_POWER 0
+
+/* LTR/LTW heat unit = 2^X ns of age */
+#define LTR_DIVIDER_POWER 30 /* LTR - time elapsed since last read(ns) */
+#define LTR_COEFF_POWER 1
+#define LTW_DIVIDER_POWER 30 /* LTW - time elapsed since last write(ns) */
+#define LTW_COEFF_POWER 1
+
+/*
+ * AVR/AVW cold unit = 2^X ns of average delta
+ * AVR/AVW heat unit = HEAT_MAX_VALUE - cold unit
+ */
+#define AVR_DIVIDER_POWER 40 /* AVR - average delta between recent reads(ns) */
+#define AVR_COEFF_POWER 0
+#define AVW_DIVIDER_POWER 40 /* AVW - average delta between recent writes(ns) */
+#define AVW_COEFF_POWER 0
+
 #endif /* __HOT_TRACKING__ */

index 3c0cf57..c32197b 100644
@@ -35,6 +35,7 @@ enum {
 
 enum {
 	HOT_DELETING,
+	HOT_IN_LIST,
 };
 
 /*

@@ -60,6 +61,7 @@ struct hot_comm_item {
 	struct rb_node rb_node;			/* rbtree index */
 	unsigned long delete_flag;
 	struct rcu_head c_rcu;
+	struct list_head track_list;		/* link to *_map[] */
 };
 
 /* An item representing an inode and its access frequency */

@@ -88,6 +90,8 @@ struct hot_info {
 	spinlock_t t_lock;				/* protect above tree */
 	struct list_head hot_map[MAX_TYPES][MAP_SIZE];	/* map of inode temp */
 	spinlock_t m_lock;
+	struct workqueue_struct *update_wq;
+	struct delayed_work update_work;
 };
 
 extern void __init hot_cache_init(void);

index 2742d9e..af4498c 100644
@@ -100,6 +100,7 @@ static void hot_comm_item_unlink(struct hot_info *root,
 			list_del_rcu(&ci->track_list);
 			spin_unlock(&root->m_lock);
 
+			atomic_dec(&root->hot_map_nr);
 			hot_comm_item_put(ci);
 		}
 

@@ -517,6 +518,7 @@ static int hot_map_update(struct hot_info *root,
 		else {
 			u32 flags = ci->hot_freq_data.flags;
 
+			atomic_inc(&root->hot_map_nr);
 			hot_comm_item_get(ci);
 
 			spin_lock(&root->m_lock);

@@ -642,6 +644,55 @@ void __init hot_cache_init(void)
 }
 EXPORT_SYMBOL_GPL(hot_cache_init);
 
+static void hot_prune_map(struct hot_info *root, long nr)
+{
+	int i;
+
+	for (i = 0; i < MAP_SIZE; i++) {
+		struct hot_comm_item *ci;
+		unsigned long prev_nr;
+
+		rcu_read_lock();
+		if (list_empty(&root->hot_map[TYPE_INODE][i])) {
+			rcu_read_unlock();
+			continue;
+		}
+
+		list_for_each_entry_rcu(ci, &root->hot_map[TYPE_INODE][i],
+					track_list) {
+			prev_nr = atomic_read(&root->hot_map_nr);
+			hot_comm_item_unlink(root, ci);
+			nr -= (prev_nr - atomic_read(&root->hot_map_nr));
+			if (nr <= 0)
+				break;
+		}
+		rcu_read_unlock();
+
+		if (nr <= 0)
+			break;
+	}
+
+	return;
+}
+
+/* The shrinker callback function */
+static int hot_track_prune(struct shrinker *shrink,
+			struct shrink_control *sc)
+{
+	struct hot_info *root =
+		container_of(shrink, struct hot_info, hot_shrink);
+
+	if (sc->nr_to_scan == 0)
+		return atomic_read(&root->hot_map_nr) / 2;
+
+	if (!(sc->gfp_mask & __GFP_FS))
+		return -1;
+
+	hot_prune_map(root, sc->nr_to_scan);
+
+	return atomic_read(&root->hot_map_nr);
+}
+
 /*
  * Main function to update i/o access frequencies, and it will be called
  * from read/writepages() hooks, which are read_pages(), do_writepages(),

@@ -706,6 +757,7 @@ static struct hot_info *hot_tree_init(struct super_block *sb)
 	root->hot_inode_tree = RB_ROOT;
 	spin_lock_init(&root->t_lock);
 	spin_lock_init(&root->m_lock);
+	atomic_set(&root->hot_map_nr, 0);
 
 	for (i = 0; i < MAP_SIZE; i++) {
 		for (j = 0; j < MAX_TYPES; j++)

@@ -726,6 +778,11 @@ static struct hot_info *hot_tree_init(struct super_block *sb)
 	queue_delayed_work(root->update_wq, &root->update_work,
 		msecs_to_jiffies(HOT_UPDATE_INTERVAL * MSEC_PER_SEC));
 
+	/* Register a shrinker callback */
+	root->hot_shrink.shrink = hot_track_prune;
+	root->hot_shrink.seeks = DEFAULT_SEEKS;
+	register_shrinker(&root->hot_shrink);
+
 	return root;
 }
 

@@ -737,6 +794,7 @@ static void hot_tree_exit(struct hot_info *root)
 	struct rb_node *node;
 	struct hot_comm_item *ci;
 
+	unregister_shrinker(&root->hot_shrink);
 	cancel_delayed_work_sync(&root->update_work);
 	destroy_workqueue(root->update_wq);
 

index c32197b..a78b4fc 100644
@@ -90,8 +90,10 @@ struct hot_info {
 	spinlock_t t_lock;				/* protect above tree */
 	struct list_head hot_map[MAX_TYPES][MAP_SIZE];	/* map of inode temp */
 	spinlock_t m_lock;
+	atomic_t hot_map_nr;
 	struct workqueue_struct *update_wq;
 	struct delayed_work update_work;
+	struct shrinker hot_shrink;
 };
 
 extern void __init hot_cache_init(void);

index 8089e35..a3fa055 100644
@@ -218,6 +218,11 @@ static inline void list_splice_init_rcu(struct list_head *list,
 	at->prev = last;
 }
 
+#define __list_for_each_rcu(pos, head)				\
+	for (pos = rcu_dereference(list_next_rcu(head));	\
+	     pos != head;						\
+	     pos = rcu_dereference(list_next_rcu(pos)))
+
 /**
  * list_entry_rcu - get the struct for this entry
  * @ptr:        the &struct list_head pointer.

index 774c1eb..301caa7 100644
@@ -795,6 +795,43 @@ struct list_head *seq_list_next(void *v, struct list_head *head, loff_t *ppos)
 }
 EXPORT_SYMBOL(seq_list_next);
 
+struct list_head *seq_list_start_rcu(struct list_head *head, loff_t pos)
+{
+	struct list_head *lh;
+
+	__list_for_each_rcu(lh, head)
+		if (pos-- == 0)
+			return lh;
+
+	return NULL;
+}
+EXPORT_SYMBOL(seq_list_start_rcu);
+
+struct list_head *seq_list_start_head_rcu(struct list_head *head, loff_t pos)
+{
+	if (!pos)
+		return head;
+
+	return seq_list_start_rcu(head, pos - 1);
+}
+EXPORT_SYMBOL(seq_list_start_head_rcu);
+
+struct list_head *seq_list_next_rcu(void *v, struct list_head *head,
+					loff_t *ppos)
+{
+	struct list_head *lh;
+
+	++*ppos;
+	rcu_read_lock();
+	lh = rcu_dereference(((struct list_head *)v)->next);
+	if (lh == head)
+		lh = NULL;
+	rcu_read_unlock();
+
+	return lh;
+}
+EXPORT_SYMBOL(seq_list_next_rcu);
+
 /**
  * seq_hlist_start - start an iteration of a hlist
  * @head: the head of the hlist

index 2da29ac..7e391c9 100644
@@ -155,6 +155,13 @@ extern struct list_head *seq_list_start_head(struct list_head *head,
 extern struct list_head *seq_list_next(void *v, struct list_head *head,
 		loff_t *ppos);
 
+extern struct list_head *seq_list_start_rcu(struct list_head *head,
+		loff_t pos);
+extern struct list_head *seq_list_start_head_rcu(struct list_head *head,
+		loff_t pos);
+extern struct list_head *seq_list_next_rcu(void *v, struct list_head *head,
+		loff_t *ppos);
+
 /*
  * Helpers for iteration over hlist_head-s in seq_files
  */

index af4498c..cea3675 100644
@@ -17,9 +17,12 @@
 #include <linux/fs.h>
 #include <linux/types.h>
 #include <linux/list_sort.h>
+#include <linux/debugfs.h>
 #include <linux/limits.h>
 #include "hot_tracking.h"
 
+static struct dentry *hot_debugfs_root;
+
 /* kmem_cache pointers for slab caches */
 static struct kmem_cache *hot_inode_item_cachep __read_mostly;
 static struct kmem_cache *hot_range_item_cachep __read_mostly;

@@ -623,6 +626,444 @@ static void hot_update_worker(struct work_struct *work)
 		msecs_to_jiffies(HOT_UPDATE_INTERVAL * MSEC_PER_SEC));
 }
 
+static void *hot_range_seq_start(struct seq_file *seq, loff_t *pos)
+	__acquires(rcu)
+{
+	struct hot_info *root = seq->private;
+	struct rb_node *node_he, *node_hr;
+	struct hot_comm_item *ci_he, *ci_hr;
+	struct hot_inode_item *he;
+	struct hot_range_item *hr;
+	loff_t l = *pos;
+
+	rcu_read_lock();
+	node_he = rb_first(&root->hot_inode_tree);
+	while (node_he) {
+		ci_he = rb_entry(node_he, struct hot_comm_item, rb_node);
+		he = container_of(ci_he, struct hot_inode_item, hot_inode);
+		node_hr = rb_first(&he->hot_range_tree);
+		while (node_hr) {
+			if (!l--) {
+				ci_hr = rb_entry(node_hr,
+					struct hot_comm_item, rb_node);
+				hr = container_of(ci_hr,
+					struct hot_range_item, hot_range);
+				return hr;
+			}
+			node_hr = rb_next(node_hr);
+		}
+		node_he = rb_next(node_he);
+	}
+
+	return NULL;
+}
+
+static void *hot_range_seq_next(struct seq_file *seq,
+				void *v, loff_t *pos)
+{
+	struct rb_node *node_he, *node_hr;
+	struct hot_comm_item *ci_he, *ci_hr;
+	struct hot_range_item *hr_next = NULL, *hr = v;
+	struct hot_inode_item *he_next;
+
+	(*pos)++;
+	node_hr = rb_next(&hr->hot_range.rb_node);
+	if (node_hr) {
+		ci_hr = rb_entry(node_hr, struct hot_comm_item, rb_node);
+		hr_next = container_of(ci_hr, struct hot_range_item, hot_range);
+
+		return hr_next;
+	}
+
+	node_he = rb_next(&hr->hot_inode->hot_inode.rb_node);
+loop_he:
+	if (node_he) {
+		ci_he = rb_entry(node_he, struct hot_comm_item, rb_node);
+		he_next = container_of(ci_he, struct hot_inode_item, hot_inode);
+		node_hr = rb_first(&he_next->hot_range_tree);
+		if (node_hr) {
+			ci_hr = rb_entry(node_hr,
+					struct hot_comm_item, rb_node);
+			hr_next = container_of(ci_hr,
+					struct hot_range_item, hot_range);
+		} else {
+			node_he = rb_next(node_he);
+			goto loop_he;
+		}
+	}
+
+	return hr_next;
+}
+
+static void hot_range_seq_stop(struct seq_file *seq, void *v)
+	__releases(rcu)
+{
+	rcu_read_unlock();
+}
+
+static int hot_range_seq_show(struct seq_file *seq, void *v)
+{
+	struct hot_range_item *hr = v;
+	struct hot_inode_item *he = hr->hot_inode;
+	struct hot_freq_data *freq_data;
+
+	freq_data = &hr->hot_range.hot_freq_data;
+	seq_printf(seq, "inode %llu, extent %llu+%llu, " \
+			"reads %u, writes %u, temp %u, " \
+			"storage type %s\n",
+			he->i_ino, (unsigned long long)hr->start,
+			(unsigned long long)hr->len,
+			freq_data->nr_reads,
+			freq_data->nr_writes,
+			(u8)hot_shift((u64)freq_data->last_temp,
+					(32 - MAP_BITS), false),
+			(hr->storage_type == 1) ? "nonrot" : "rot");
+
+	return 0;
+}
+
+static void *hot_inode_seq_start(struct seq_file *seq, loff_t *pos)
+	__acquires(rcu)
+{
+	struct hot_info *root = seq->private;
+	struct rb_node *node;
+	struct hot_comm_item *ci;
+	struct hot_inode_item *he = NULL;
+	loff_t l = *pos;
+
+	rcu_read_lock();
+	node = rb_first(&root->hot_inode_tree);
+	while (node) {
+		if (!l--) {
+			ci = rb_entry(node, struct hot_comm_item, rb_node);
+			he = container_of(ci, struct hot_inode_item, hot_inode);
+			break;
+		}
+		node = rb_next(node);
+	}
+
+	return he;
+}
+
+static void *hot_inode_seq_next(struct seq_file *seq, void *v, loff_t *pos)
+{
+	struct hot_inode_item *he_next = NULL, *he = v;
+	struct rb_node *node;
+	struct hot_comm_item *ci;
+
+	(*pos)++;
+	node = rb_next(&he->hot_inode.rb_node);
+	if (node) {
+		ci = rb_entry(node, struct hot_comm_item, rb_node);
+		he_next = container_of(ci, struct hot_inode_item, hot_inode);
+	}
+
+	return he_next;
+}
+
+static void hot_inode_seq_stop(struct seq_file *seq, void *v)
+	__releases(rcu)
+{
+	rcu_read_unlock();
+}
+
+static int hot_inode_seq_show(struct seq_file *seq, void *v)
+{
+	struct hot_inode_item *he = v;
+	struct hot_freq_data *freq_data = &he->hot_inode.hot_freq_data;
+
+	seq_printf(seq, "inode %llu, reads %u, writes %u, temp %d\n",
+		he->i_ino,
+		freq_data->nr_reads,
+		freq_data->nr_writes,
+		(u8)hot_shift((u64)freq_data->last_temp,
+				(32 - MAP_BITS), false));
+
+	return 0;
+}
+
+static struct hot_comm_item *hot_spot_seq_start(struct hot_info *root,
+					loff_t *pos, int type)
+	__acquires(rcu)
+{
+	struct hot_comm_item *ci;
+	struct list_head *track_list;
+	int i;
+
+	rcu_read_lock();
+	for (i = MAP_SIZE - 1; i >= 0; i--) {
+		track_list = seq_list_start_rcu(&root->hot_map[type][i], *pos);
+		if (track_list) {
+			ci = container_of(track_list,
+				struct hot_comm_item, track_list);
+			return ci;
+		}
+	}
+
+	return NULL;
+}
+
+static struct hot_comm_item *hot_spot_seq_next(struct hot_info *root,
+					struct hot_comm_item *ci,
+					loff_t *pos, int type)
+{
+	struct hot_comm_item *ci_next = NULL;
+	struct list_head *track_list;
+	int i;
+
+	i = (int)hot_shift(ci->hot_freq_data.last_temp,
+			(32 - MAP_BITS), false);
+
+	track_list = seq_list_next_rcu(&ci->track_list,
+				&root->hot_map[type][i], pos);
+next:
+	if (track_list)
+		ci_next = container_of(track_list,
+				struct hot_comm_item, track_list);
+	else if (--i >= 0) {
+		track_list = seq_list_next_rcu(&root->hot_map[type][i],
+					&root->hot_map[type][i], pos);
+		goto next;
+	}
+
+	return ci_next;
+}
+
+static void *hot_spot_range_seq_start(struct seq_file *seq, loff_t *pos)
+{
+	struct hot_info *root = seq->private;
+	struct hot_range_item *hr = NULL;
+	struct hot_comm_item *ci;
+
+	ci =  hot_spot_seq_start(root, pos, TYPE_RANGE);
+	if (ci)
+		hr = container_of(ci, struct hot_range_item, hot_range);
+
+	return hr;
+}
+
+static void *hot_spot_range_seq_next(struct seq_file *seq, void *v, loff_t *pos)
+{
+	struct hot_info *root = seq->private;
+	struct hot_range_item *hr_next = NULL, *hr = v;
+	struct hot_comm_item *ci_next;
+
+	ci_next = hot_spot_seq_next(root, &hr->hot_range, pos, TYPE_RANGE);
+	if (ci_next)
+		hr_next = container_of(ci_next,
+				struct hot_range_item, hot_range);
+
+	return hr_next;
+}
+
+static void *hot_spot_inode_seq_start(struct seq_file *seq, loff_t *pos)
+{
+	struct hot_info *root = seq->private;
+	struct hot_inode_item *he = NULL;
+	struct hot_comm_item *ci;
+
+	ci = hot_spot_seq_start(root, pos, TYPE_INODE);
+	if (ci)
+		he = container_of(ci, struct hot_inode_item, hot_inode);
+
+	return he;
+}
+
+static void *hot_spot_inode_seq_next(struct seq_file *seq, void *v, loff_t *pos)
+{
+	struct hot_info *root = seq->private;
+	struct hot_inode_item *he_next = NULL, *he = v;
+	struct hot_comm_item *ci_next;
+
+	ci_next = hot_spot_seq_next(root, &he->hot_inode, pos, TYPE_INODE);
+	if (ci_next)
+		he_next = container_of(ci_next,
+				struct hot_inode_item, hot_inode);
+
+	return he_next;
+}
+
+static const struct seq_operations hot_range_seq_ops = {
+	.start = hot_range_seq_start,
+	.next = hot_range_seq_next,
+	.stop = hot_range_seq_stop,
+	.show = hot_range_seq_show
+};
+
+static const struct seq_operations hot_inode_seq_ops = {
+	.start = hot_inode_seq_start,
+	.next = hot_inode_seq_next,
+	.stop = hot_inode_seq_stop,
+	.show = hot_inode_seq_show
+};
+
+static const struct seq_operations hot_spot_range_seq_ops = {
+	.start = hot_spot_range_seq_start,
+	.next = hot_spot_range_seq_next,
+	.stop = hot_range_seq_stop,
+	.show = hot_range_seq_show
+};
+
+static const struct seq_operations hot_spot_inode_seq_ops = {
+	.start = hot_spot_inode_seq_start,
+	.next = hot_spot_inode_seq_next,
+	.stop = hot_inode_seq_stop,
+	.show = hot_inode_seq_show
+};
+
+static int hot_range_seq_open(struct inode *inode, struct file *file)
+{
+	int ret = seq_open_private(file, &hot_range_seq_ops, 0);
+	if (ret == 0) {
+		struct seq_file *seq = file->private_data;
+		seq->private = inode->i_private;
+	}
+	return ret;
+}
+
+static int hot_inode_seq_open(struct inode *inode, struct file *file)
+{
+	int ret = seq_open_private(file, &hot_inode_seq_ops, 0);
+	if (ret == 0) {
+		struct seq_file *seq = file->private_data;
+		seq->private = inode->i_private;
+	}
+	return ret;
+}
+
+static int hot_spot_range_seq_open(struct inode *inode, struct file *file)
+{
+	int ret = seq_open_private(file, &hot_spot_range_seq_ops, 0);
+	if (ret == 0) {
+		struct seq_file *seq = file->private_data;
+		seq->private = inode->i_private;
+	}
+	return ret;
+}
+
+static int hot_spot_inode_seq_open(struct inode *inode, struct file *file)
+{
+	int ret = seq_open_private(file, &hot_spot_inode_seq_ops, 0);
+	if (ret == 0) {
+		struct seq_file *seq = file->private_data;
+		seq->private = inode->i_private;
+	}
+	return ret;
+}
+
+/* fops to override for printing range data */
+static const struct file_operations hot_debugfs_range_fops = {
+	.open = hot_range_seq_open,
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.release = seq_release,
+};
+
+/* fops to override for printing inode data */
+static const struct file_operations hot_debugfs_inode_fops = {
+	.open = hot_inode_seq_open,
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.release = seq_release,
+};
+
+/* fops to override for printing temperature data */
+static const struct file_operations hot_debugfs_spot_range_fops = {
+	.open = hot_spot_range_seq_open,
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.release = seq_release,
+};
+
+static const struct file_operations hot_debugfs_spot_inode_fops = {
+	.open = hot_spot_inode_seq_open,
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.release = seq_release,
+};
+
+static const struct hot_debugfs hot_debugfs[] = {
+	{
+		.name = "extent_stat",
+		.fops  = &hot_debugfs_range_fops,
+	},
+	{
+		.name = "inode_stat",
+		.fops  = &hot_debugfs_inode_fops,
+	},
+	{
+		.name = "extent_spot",
+		.fops  = &hot_debugfs_spot_range_fops,
+	},
+	{
+		.name = "inode_spot",
+		.fops  = &hot_debugfs_spot_inode_fops,
+	},
+};
+
+/* initialize debugfs */
+static int hot_debugfs_init(struct super_block *sb)
+{
+	static const char hot_name[] = "hot_track";
+	struct dentry *dentry;
+	int i, ret = 0;
+
+	/* Determine if hot debufs root has existed */
+	if (!hot_debugfs_root) {
+		hot_debugfs_root = debugfs_create_dir(hot_name, NULL);
+		if (IS_ERR(hot_debugfs_root)) {
+			ret = PTR_ERR(hot_debugfs_root);
+			return ret;
+		}
+	}
+
+	/* create debugfs folder for this volume by mounted dev name */
+	sb->s_hot_root->debugfs_dentry =
+			debugfs_create_dir(sb->s_id, hot_debugfs_root);
+	if (IS_ERR(sb->s_hot_root->debugfs_dentry)) {
+		ret = PTR_ERR(sb->s_hot_root->debugfs_dentry);
+		goto root_err;
+	}
+
+	/* create debugfs hot data files */
+	for (i = 0; i < ARRAY_SIZE(hot_debugfs); i++) {
+		dentry = debugfs_create_file(hot_debugfs[i].name,
+					S_IFREG | S_IRUSR | S_IWUSR,
+					sb->s_hot_root->debugfs_dentry,
+					sb->s_hot_root,
+					hot_debugfs[i].fops);
+		if (IS_ERR(dentry)) {
+			ret = PTR_ERR(dentry);
+			goto err;
+		}
+	}
+
+	return 0;
+
+err:
+	debugfs_remove_recursive(sb->s_hot_root->debugfs_dentry);
+
+root_err:
+	if (list_empty(&hot_debugfs_root->d_subdirs)) {
+		debugfs_remove(hot_debugfs_root);
+		hot_debugfs_root = NULL;
+	}
+
+	return ret;
+}
+
+/* remove dentries for debugsfs */
+static void hot_debugfs_exit(struct super_block *sb)
+{
+	/* remove all debugfs entries recursively from the volume root */
+	debugfs_remove_recursive(sb->s_hot_root->debugfs_dentry);
+
+	if (list_empty(&hot_debugfs_root->d_subdirs)) {
+		debugfs_remove(hot_debugfs_root);
+		hot_debugfs_root = NULL;
+	}
+}
+
 /*
  * Initialize kmem cache for hot_inode_item and hot_range_item.
  */

@@ -818,6 +1259,7 @@ static void hot_tree_exit(struct hot_info *root)
 int hot_track_init(struct super_block *sb)
 {
 	struct hot_info *root;
+	int ret;
 
 	root = hot_tree_init(sb);
 	if (IS_ERR(root))

@@ -825,9 +1267,21 @@ int hot_track_init(struct super_block *sb)
 
 	sb->s_hot_root = root;
 
+	ret = hot_debugfs_init(sb);
+	if (ret) {
+		printk(KERN_ERR "%s: hot_debugfs_init error: %d\n",
+				__func__, ret);
+		goto out;
+	}
+
 	printk(KERN_INFO "VFS: Turning on hot data tracking\n");
 
 	return 0;
+
+out:
+	hot_tree_exit(root);
+	sb->s_hot_root = NULL;
+	return ret;
 }
 EXPORT_SYMBOL_GPL(hot_track_init);
 

@@ -840,6 +1294,7 @@ void hot_track_exit(struct super_block *sb)
 {
 	struct hot_info *root = sb->s_hot_root;
 
+	hot_debugfs_exit(sb);
 	hot_tree_exit(root);
 	sb->s_hot_root = NULL;
 	kfree(root);

index 8a53c2d..fcc60ac 100644
@@ -43,4 +43,9 @@
 #define AVW_DIVIDER_POWER 40 /* AVW - average delta between recent writes(ns) */
 #define AVW_COEFF_POWER 0
 
+struct hot_debugfs {
+	const char *name;
+	const struct file_operations *fops;
+};
+
 #endif /* __HOT_TRACKING__ */

index a78b4fc..63baae3 100644
@@ -94,6 +94,7 @@ struct hot_info {
 	struct workqueue_struct *update_wq;
 	struct delayed_work update_work;
 	struct shrinker hot_shrink;
+	struct dentry *debugfs_dentry;
 };
 
 extern void __init hot_cache_init(void);

index 996cdc5..97bf972 100644
@@ -57,6 +57,7 @@
 #include <linux/i2c-dev.h>
 #include <linux/atalk.h>
 #include <linux/gfp.h>
+#include <linux/hot_tracking.h>
 
 #include <net/bluetooth/bluetooth.h>
 #include <net/bluetooth/hci.h>

@@ -1402,6 +1403,9 @@ COMPATIBLE_IOCTL(TIOCSTART)
 COMPATIBLE_IOCTL(TIOCSTOP)
 #endif
 
+/*Hot data tracking*/
+COMPATIBLE_IOCTL(FS_IOC_GET_HEAT_INFO)
+
 /* fat 'r' ioctls. These are handled by fat with ->compat_ioctl,
    but we don't want warnings on other file systems. So declare
    them as compatible here. */

@@ -1581,6 +1585,7 @@ asmlinkage long compat_sys_ioctl(unsigned int fd, unsigned int cmd,
 	case FIBMAP:
 	case FIGETBSZ:
 	case FIONREAD:
+	case FS_IOC_GET_HEAT_INFO:
 		if (S_ISREG(file_inode(f.file)->i_mode))
 			break;
 		/*FALL THROUGH*/

index cea3675..1618f21 100644
@@ -375,7 +375,7 @@ static void hot_freq_update(struct hot_info *root,
  * the *_COEFF_POWER values and combined to a single temperature
  * value.
  */
-static u32 hot_temp_calc(struct hot_comm_item *ci)
+u32 hot_temp_calc(struct hot_comm_item *ci)
 {
 	u32 result = 0;
 	struct hot_freq_data *freq_data = &ci->hot_freq_data;

88 lines not on this page · raw message

index 63baae3..263a15e 100644
@@ -17,6 +17,18 @@
 
 #include <linux/types.h>
 
+struct hot_heat_info {
+	__u64 avg_delta_reads;
+	__u64 avg_delta_writes;
+	__u64 last_read_time;
+	__u64 last_write_time;
+	__u32 num_reads;
+	__u32 num_writes;
+	__u32 temp;
+	__u8 live;
+	__u8 resv[3];
+};
+
 #ifdef __KERNEL__
 
 #include <linux/rbtree.h>

@@ -97,6 +109,14 @@ struct hot_info {
 	struct dentry *debugfs_dentry;
 };
 
+/*
+ * Hot data tracking ioctls:
+ *
+ * HOT_INFO - retrieve info on frequency of access
+ */
+#define FS_IOC_GET_HEAT_INFO _IOR('f', 17, \
+			struct hot_heat_info)
+
 extern void __init hot_cache_init(void);
 extern int hot_track_init(struct super_block *sb);
 extern void hot_track_exit(struct super_block *sb);

@@ -108,6 +128,7 @@ extern struct hot_inode_item *hot_inode_item_lookup(struct hot_info *root,
 extern struct hot_range_item *hot_range_item_lookup(struct hot_inode_item *he,
 						loff_t start, int alloc);
 extern void hot_inode_item_delete(struct inode *inode);
+extern u32 hot_temp_calc(struct hot_comm_item *ci);
 
 static inline u64 hot_shift(u64 counter, u32 bits, bool dir)
 {

index 1618f21..088e9aa 100644
@@ -23,6 +23,12 @@
 
 static struct dentry *hot_debugfs_root;
 
+int sysctl_hot_age_interval __read_mostly = 300;
+EXPORT_SYMBOL_GPL(sysctl_hot_age_interval);
+
+int sysctl_hot_update_interval __read_mostly = 300;
+EXPORT_SYMBOL_GPL(sysctl_hot_update_interval);
+
 /* kmem_cache pointers for slab caches */
 static struct kmem_cache *hot_inode_item_cachep __read_mostly;
 static struct kmem_cache *hot_range_item_cachep __read_mostly;

@@ -446,7 +452,7 @@ static bool hot_is_obsolete(struct hot_comm_item *ci)
 	struct hot_freq_data *freq_data = &ci->hot_freq_data;
 	u64 last_read_ns, last_write_ns;
 	u64 cur_time = timespec_to_ns(&ckt);
-	u64 kick_ns =  HOT_AGE_INTERVAL * NSEC_PER_SEC;
+	u64 kick_ns =  sysctl_hot_age_interval * NSEC_PER_SEC;
 
 	last_read_ns =
 		(cur_time - timespec_to_ns(&freq_data->last_read_time));

@@ -623,7 +629,7 @@ static void hot_update_worker(struct work_struct *work)
 
 	/* Instert next delayed work */
 	queue_delayed_work(root->update_wq, &root->update_work,
-		msecs_to_jiffies(HOT_UPDATE_INTERVAL * MSEC_PER_SEC));
+		msecs_to_jiffies(sysctl_hot_update_interval * MSEC_PER_SEC));
 }
 
 static void *hot_range_seq_start(struct seq_file *seq, loff_t *pos)

@@ -1217,7 +1223,7 @@ static struct hot_info *hot_tree_init(struct super_block *sb)
 	/* 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(HOT_UPDATE_INTERVAL * MSEC_PER_SEC));
+		msecs_to_jiffies(sysctl_hot_update_interval * MSEC_PER_SEC));
 
 	/* Register a shrinker callback */
 	root->hot_shrink.shrink = hot_track_prune;

index fcc60ac..d1ab48b 100644
@@ -15,9 +15,6 @@
 #include <linux/workqueue.h>
 #include <linux/hot_tracking.h>
 
-#define HOT_UPDATE_INTERVAL 150
-#define HOT_AGE_INTERVAL 300
-
 /* size of sub-file ranges */
 #define RANGE_BITS 20
 #define FREQ_POWER 4

index 263a15e..6de7153 100644
@@ -110,6 +110,13 @@ struct hot_info {
 };
 
 /*
+ * Two variables have meanings as below:
+ * 1. time to quit keeping track of tracking data (seconds)
+ * 2. set how often to update temperatures (seconds)
+ */
+extern int sysctl_hot_age_interval, sysctl_hot_update_interval;
+
+/*
  * Hot data tracking ioctls:
  *
  * HOT_INFO - retrieve info on frequency of access

index 9edcf45..6ee4338 100644
@@ -1616,6 +1616,20 @@ static struct ctl_table fs_table[] = {
 		.proc_handler	= &pipe_proc_fn,
 		.extra1		= &pipe_min_size,
 	},
+	{
+		.procname	= "hot-age-interval",
+		.data		= &sysctl_hot_age_interval,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec,
+	},
+	{
+		.procname	= "hot-update-interval",
+		.data		= &sysctl_hot_update_interval,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec,
+	},
 	{ }
 };
 

index 63c328a..133a6ed 100644
@@ -1927,6 +1927,7 @@ struct btrfs_ioctl_defrag_range_args {
 #define BTRFS_MOUNT_CHECK_INTEGRITY	(1 << 20)
 #define BTRFS_MOUNT_CHECK_INTEGRITY_INCLUDING_EXTENT_DATA (1 << 21)
 #define BTRFS_MOUNT_PANIC_ON_FATAL_ERROR	(1 << 22)
+#define BTRFS_MOUNT_HOT_TRACK		(1 << 23)
 
 #define btrfs_clear_opt(o, opt)		((o) &= ~BTRFS_MOUNT_##opt)
 #define btrfs_set_opt(o, opt)		((o) |= BTRFS_MOUNT_##opt)

index a4807ce..09fb9d2 100644
@@ -42,6 +42,7 @@
 #include <linux/cleancache.h>
 #include <linux/ratelimit.h>
 #include <linux/btrfs.h>
+#include <linux/hot_tracking.h>
 #include "compat.h"
 #include "delayed-inode.h"
 #include "ctree.h"

@@ -306,6 +307,10 @@ static void btrfs_put_super(struct super_block *sb)
 	 * last process that kept it busy.  Or segfault in the aforementioned
 	 * process...  Whom would you report that to?
 	 */
+
+	/* Hot data tracking */
+	if (btrfs_test_opt(btrfs_sb(sb)->tree_root, HOT_TRACK))
+		hot_track_exit(sb);
 }
 
 enum {

@@ -318,7 +323,7 @@ enum {
 	Opt_enospc_debug, Opt_subvolrootid, Opt_defrag, Opt_inode_cache,
 	Opt_no_space_cache, Opt_recovery, Opt_skip_balance,
 	Opt_check_integrity, Opt_check_integrity_including_extent_data,
-	Opt_check_integrity_print_mask, Opt_fatal_errors,
+	Opt_check_integrity_print_mask, Opt_fatal_errors, Opt_hot_track,
 	Opt_err,
 };
 

@@ -359,6 +364,7 @@ static match_table_t tokens = {
 	{Opt_check_integrity_including_extent_data, "check_int_data"},
 	{Opt_check_integrity_print_mask, "check_int_print_mask=%d"},
 	{Opt_fatal_errors, "fatal_errors=%s"},
+	{Opt_hot_track, "hot_track"},
 	{Opt_err, NULL},
 };
 

@@ -624,6 +630,9 @@ int btrfs_parse_options(struct btrfs_root *root, char *options)
 				goto out;
 			}
 			break;
+		case Opt_hot_track:
+			btrfs_set_opt(info->mount_opt, HOT_TRACK);
+			break;
 		case Opt_err:
 			printk(KERN_INFO "btrfs: unrecognized mount option "
 			       "'%s'\n", p);

@@ -843,11 +852,20 @@ static int btrfs_fill_super(struct super_block *sb,
 		goto fail_close;
 	}
 
+	if (btrfs_test_opt(fs_info->tree_root, HOT_TRACK)) {
+		err = hot_track_init(sb);
+		if (err)
+			goto fail_hot;
+	}
+
 	save_mount_options(sb, data);
 	cleancache_init_fs(sb);
 	sb->s_flags |= MS_ACTIVE;
 	return 0;
 
+fail_hot:
+	dput(sb->s_root);
+	sb->s_root = NULL;
 fail_close:
 	close_ctree(fs_info->tree_root);
 	return err;

@@ -943,6 +961,8 @@ static int btrfs_show_options(struct seq_file *seq, struct dentry *dentry)
 		seq_puts(seq, ",skip_balance");
 	if (btrfs_test_opt(root, PANIC_ON_FATAL_ERROR))
 		seq_puts(seq, ",fatal_errors=panic");
+	if (btrfs_test_opt(root, HOT_TRACK))
+		seq_puts(seq, ",hot_track");
 	return 0;
 }
 

index 088e9aa..4eee33c 100644
@@ -51,7 +51,7 @@ static void hot_range_item_init(struct hot_range_item *hr,
 			struct hot_inode_item *he, loff_t start)
 {
 	hr->start = start;
-	hr->len = hot_shift(1, RANGE_BITS, true);
+	hr->len = hot_shift(1, he->hot_root->hot_type->range_bits, true);
 	hr->hot_inode = he;
 	hr->storage_type = -1;
 	hot_comm_item_init(&hr->hot_range, TYPE_RANGE);

@@ -259,10 +259,11 @@ struct hot_range_item
 {
 	struct rb_node **p;
 	struct rb_node *parent = NULL;
+	struct hot_info *root = he->hot_root;
 	struct hot_comm_item *ci;
 	struct hot_range_item *hr, *hr_new = NULL;
 
-	start = hot_shift(start, RANGE_BITS, true);
+	start = hot_shift(start, root->hot_type->range_bits, true);
 
 	/* walk tree to find insertion point */
 redo:

@@ -350,13 +351,13 @@ static void hot_freq_update(struct hot_info *root,
 
 	if (write) {
 		freq_data->nr_writes += 1;
-		hot_freq_calc(freq_data->last_write_time,
+		HOT_FREQ_CALC(root, freq_data->last_write_time,
 				cur_time,
 				&freq_data->avg_delta_writes);
 		freq_data->last_write_time = cur_time;
 	} else {
 		freq_data->nr_reads += 1;
-		hot_freq_calc(freq_data->last_read_time,
+		HOT_FREQ_CALC(root, freq_data->last_read_time,
 				cur_time,
 				&freq_data->avg_delta_reads);
 		freq_data->last_read_time = cur_time;

@@ -381,7 +382,7 @@ static void hot_freq_update(struct hot_info *root,
  * the *_COEFF_POWER values and combined to a single temperature
  * value.
  */
-u32 hot_temp_calc(struct hot_comm_item *ci)
+static u32 hot_temp_calc(struct hot_comm_item *ci)
 {
 	u32 result = 0;
 	struct hot_freq_data *freq_data = &ci->hot_freq_data;

@@ -501,7 +502,7 @@ static void hot_comm_item_link_cb(struct rcu_head *head)
 static int hot_map_update(struct hot_info *root,
 			struct hot_comm_item *ci)
 {
-	u32 temp = hot_temp_calc(ci);
+	u32 temp = HOT_TEMP_CALC(root, ci);
 	u8 cur_temp, prev_temp;
 	int flag = false;
 

@@ -564,7 +565,7 @@ static void hot_range_update(struct hot_inode_item *he,
 			hot_map_update(root, ci)) {
 			continue;
 		}
-		obsolete = hot_is_obsolete(ci);
+		obsolete = HOT_IS_OBSOLETE(root, ci);
 		if (obsolete)
 			hot_comm_item_unlink(root, ci);
 	}

@@ -1167,10 +1168,10 @@ void hot_update_freqs(struct inode *inode, loff_t start,
 	 * Align ranges on range size boundary
 	 * to prevent proliferation of range structs
 	 */
-	range_size  = hot_shift(1, RANGE_BITS, true);
+	range_size  = hot_shift(1, root->hot_type->range_bits, true);
 	end = hot_shift((start + len + range_size - 1),
-			RANGE_BITS, false);
-	cur = hot_shift(start, RANGE_BITS, false);
+			root->hot_type->range_bits, false);
+	cur = hot_shift(start, root->hot_type->range_bits, false);
 	for (; cur < end; cur++) {
 		hr = hot_range_item_lookup(he, cur, 1);
 		if (IS_ERR(hr)) {

@@ -1211,6 +1212,17 @@ static struct hot_info *hot_tree_init(struct super_block *sb)
 			INIT_LIST_HEAD(&root->hot_map[j][i]);
 	}
 
+	/* Get hot type for specific FS */
+	root->hot_type = &sb->s_type->hot_type;
+	if (!HOT_FREQ_FN_EXIST(root))
+		SET_HOT_FREQ_FN(root, hot_freq_calc);
+	if (!HOT_TEMP_FN_EXIST(root))
+		SET_HOT_TEMP_FN(root, hot_temp_calc);
+	if (!HOT_OBSOLETE_FN_EXIST(root))
+		SET_HOT_OBSOLETE_FN(root, hot_is_obsolete);
+	if (root->hot_type->range_bits == 0)
+		root->hot_type->range_bits = RANGE_BITS;
+
 	root->update_wq = alloc_workqueue(
 			"hot_update_wq", WQ_NON_REENTRANT, 0);
 	if (!root->update_wq) {

index d1ab48b..4756fc3 100644
@@ -40,6 +40,25 @@
 #define AVW_DIVIDER_POWER 40 /* AVW - average delta between recent writes(ns) */
 #define AVW_COEFF_POWER 0
 
+#define HOT_FREQ_FN_EXIST(root) \
+	((root)->hot_type->ops.hot_freq_calc)
+#define HOT_TEMP_FN_EXIST(root) \
+	((root)->hot_type->ops.hot_temp_calc)
+#define HOT_OBSOLETE_FN_EXIST(root) \
+	((root)->hot_type->ops.hot_is_obsolete)
+
+#define HOT_FREQ_CALC(root, lt, ct, avg) \
+	((root)->hot_type->ops.hot_freq_calc(lt, ct, avg))
+#define HOT_IS_OBSOLETE(root, ci) \
+	((root)->hot_type->ops.hot_is_obsolete(ci))
+
+#define SET_HOT_FREQ_FN(root, fn) \
+	(root)->hot_type->ops.hot_freq_calc = fn
+#define SET_HOT_TEMP_FN(root, fn) \
+	(root)->hot_type->ops.hot_temp_calc = fn
+#define SET_HOT_OBSOLETE_FN(root, fn) \
+	(root)->hot_type->ops.hot_is_obsolete = fn
+
 struct hot_debugfs {
 	const char *name;
 	const struct file_operations *fops;

index f9f3497..95ec029 100644
@@ -585,7 +585,7 @@ static int ioctl_heat_info(struct file *file, void __user *argp)
 		 * got a request for live temperature,
 		 * call hot_calc_temp() to recalculate
 		 */
-		heat_info.temp = hot_temp_calc(&he->hot_inode);
+		heat_info.temp = HOT_TEMP_CALC(he->hot_root, &he->hot_inode);
 	} else {
 		/* not live temperature, get it from the map list */
 		heat_info.temp = he->hot_inode.hot_freq_data.last_temp;

index ee2c54f..dda3b9c 100644
@@ -1817,6 +1817,7 @@ struct file_system_type {
 	struct dentry *(*mount) (struct file_system_type *, int,
 		       const char *, void *);
 	void (*kill_sb) (struct super_block *);
+	struct hot_type hot_type;
 	struct module *owner;
 	struct file_system_type * next;
 	struct hlist_head fs_supers;

index 6de7153..6184296 100644
@@ -97,6 +97,26 @@ struct hot_range_item {
 	int storage_type;			/* type of storage */
 };
 
+typedef void (hot_freq_calc_fn) (struct timespec old_atime,
+				struct timespec cur_time, u64 *avg);
+typedef u32 (hot_temp_calc_fn) (struct hot_comm_item *ci);
+typedef bool (hot_is_obsolete_fn) (struct hot_comm_item *ci);
+
+struct hot_func_ops {
+	hot_freq_calc_fn *hot_freq_calc;
+	hot_temp_calc_fn *hot_temp_calc;
+	hot_is_obsolete_fn *hot_is_obsolete;
+};
+
+/* identifies an hot type */
+struct hot_type {
+	u64 range_bits;
+	struct hot_func_ops ops;	/* fields provided by specific FS */
+};
+
+#define HOT_TEMP_CALC(root, ci) \
+	((root)->hot_type->ops.hot_temp_calc(ci))
+
 struct hot_info {
 	struct rb_root hot_inode_tree;
 	spinlock_t t_lock;				/* protect above tree */

@@ -105,6 +125,7 @@ struct hot_info {
 	atomic_t hot_map_nr;
 	struct workqueue_struct *update_wq;
 	struct delayed_work update_work;
+	struct hot_type *hot_type;
 	struct shrinker hot_shrink;
 	struct dentry *debugfs_dentry;
 };

@@ -135,7 +156,6 @@ extern struct hot_inode_item *hot_inode_item_lookup(struct hot_info *root,
 extern struct hot_range_item *hot_range_item_lookup(struct hot_inode_item *he,
 						loff_t start, int alloc);
 extern void hot_inode_item_delete(struct inode *inode);
-extern u32 hot_temp_calc(struct hot_comm_item *ci);
 
 static inline u64 hot_shift(u64 counter, u32 bits, bool dir)
 {