[PATCH v6 07/11] VFS hot tracking: Add a /proc interface to control memory usage

Zhi Yong Wu
2013-11-06T13:48:37Z

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

Introduce a /proc interface hot-mem-high-thresh and
to cap the memory which is consumed by hot_inode_item
and hot_range_item, and they will be in the unit of
1M bytes.

Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com>
Signed-off-by: Zhi Yong Wu <wuzhy@linux.vnet.ibm.com>
---
fs/hot_tracking.c | 29 +++++++++++++++++++++++++++++
fs/hot_tracking.h | 23 +++++++++++++++++++++++
include/linux/hot_tracking.h | 3 +++
kernel/sysctl.c | 7 +++++++
4 files changed, 62 insertions(+)

diff --git a/fs/hot_tracking.c b/fs/hot_tracking.c
index 7a9bd4f..2c5a7fd 100644
--- a/fs/hot_tracking.c
+++ b/fs/hot_tracking.c
@@ -15,6 +15,7 @@
#include <linux/sched.h>
#include "hot_tracking.h"

+int sysctl_hot_mem_high_thresh __read_mostly = 0;
int sysctl_hot_update_interval __read_mostly = 150;

/* kmem_cache pointers for slab caches */
@@ -32,6 +33,7 @@ static void hot_range_item_init(struct hot_range_item *hr,
hr->len = 1 << RANGE_BITS;
hr->hot_inode = he;
atomic_long_inc(&he->hot_root->hot_cnt);
+ hot_mem_limit_add(he->hot_root, sizeof(struct hot_range_item));
}

static void hot_range_item_free_cb(struct rcu_head *head)
@@ -55,6 +57,7 @@ static void hot_range_item_free(struct kref *kref)
spin_unlock(&root->m_lock);

atomic_long_dec(&root->hot_cnt);
+ hot_mem_limit_sub(root, sizeof(struct hot_range_item));
call_rcu(&hr->rcu, hot_range_item_free_cb);
}

@@ -103,6 +106,8 @@ redo:
* newly allocated item.
*/
atomic_long_dec(&he->hot_root->hot_cnt);
+ hot_mem_limit_sub(he->hot_root,
+ sizeof(struct hot_range_item));
kmem_cache_free(hot_range_item_cachep, hr_new);
}
spin_unlock(&he->i_lock);
@@ -205,6 +210,7 @@ static void hot_inode_item_init(struct hot_inode_item *he,
he->hot_root = root;
spin_lock_init(&he->i_lock);
atomic_long_inc(&root->hot_cnt);
+ hot_mem_limit_add(root, sizeof(struct hot_inode_item));
}

static void hot_inode_item_free_cb(struct rcu_head *head)
@@ -226,6 +232,7 @@ static void hot_inode_item_free(struct kref *kref)
hot_range_tree_free(he);

atomic_long_dec(&he->hot_root->hot_cnt);
+ hot_mem_limit_sub(he->hot_root, sizeof(struct hot_inode_item));
call_rcu(&he->rcu, hot_inode_item_free_cb);
}

@@ -272,6 +279,8 @@ redo:
* newly allocated item.
*/
atomic_long_dec(&root->hot_cnt);
+ hot_mem_limit_sub(root,
+ sizeof(struct hot_inode_item));
kmem_cache_free(hot_inode_item_cachep, he_new);
}
spin_unlock(&root->t_lock);
@@ -534,6 +543,23 @@ static unsigned long hot_item_evict(struct hot_info *root, unsigned long work,
return freed;
}

+static void hot_mem_evict(struct hot_info *root)
+{
+ unsigned long sum, thresh;
+
+ if (sysctl_hot_mem_high_thresh == 0)
+ return;
+
+ sum = hot_mem_limit_sum(root);
+ /* Note: sysctl_** is in the unit of 1M bytes */
+ thresh = sysctl_hot_mem_high_thresh;
+ thresh *= 1024 * 1024;
+ if (sum <= thresh)
+ return;
+
+ hot_item_evict(root, sum - thresh, hot_mem_limit_sum);
+}
+
/*
* Every sync period we update temperatures for
* each hot inode item and hot range item for aging
@@ -546,6 +572,8 @@ static void hot_update_worker(struct work_struct *work)
struct hot_inode_item *he;
struct rb_node *node;

+ hot_mem_evict(root);
+
rcu_read_lock();
node = root->hot_inode_tree.rb_node;
while (node) {
@@ -753,6 +781,7 @@ int hot_track_init(struct super_block *sb)
goto err;
}

+ hot_mem_limit_init(root);
sb->s_hot_root = root;
sb->s_flags |= MS_HOTTRACK;

diff --git a/fs/hot_tracking.h b/fs/hot_tracking.h
index 6a6971e..4ee0b90 100644
--- a/fs/hot_tracking.h
+++ b/fs/hot_tracking.h
@@ -46,4 +46,27 @@ struct hot_inode_item *hot_inode_item_lookup(struct hot_info *root, u64 ino);
void hot_inode_item_unlink(struct inode *inode);
u32 hot_temp_calc(struct hot_freq *freq);

+/* Memory Tracking Functions. */
+static inline unsigned long hot_mem_limit_sum(struct hot_info *root)
+{
+ return atomic_long_read(&root->mem);
+}
+
+static inline void hot_mem_limit_sub(struct hot_info *root,
+ unsigned long count)
+{
+ atomic_long_sub(count, &root->mem);
+}
+
+static inline void hot_mem_limit_add(struct hot_info *root,
+ unsigned long count)
+{
+ atomic_long_add(count, &root->mem);
+}
+
+static inline void hot_mem_limit_init(struct hot_info *root)
+{
+ atomic_long_set(&root->mem, 0);
+}
+
#endif /* __HOT_TRACKING__ */
diff --git a/include/linux/hot_tracking.h b/include/linux/hot_tracking.h
index 43df1b9..5c2c247 100644
--- a/include/linux/hot_tracking.h
+++ b/include/linux/hot_tracking.h
@@ -83,10 +83,13 @@ struct hot_info {
struct workqueue_struct *update_wq;
struct delayed_work update_work;
struct shrinker hot_shrink;
+ atomic_long_t mem;
};

/* set how often to update temperatures (seconds) */
extern int sysctl_hot_update_interval;
+/* note: sysctl_** is in the unit of 1M bytes */
+extern int sysctl_hot_mem_high_thresh;

/*
* Hot data tracking ioctls:
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index e0b062a..fde8bc2 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -1632,6 +1632,13 @@ static struct ctl_table fs_table[] = {
.extra1 = &pipe_min_size,
},
{
+ .procname = "hot-mem-high-thresh",
+ .data = &sysctl_hot_mem_high_thresh,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = proc_dointvec,
+ },
+ {
.procname = "hot-update-interval",
.data = &sysctl_hot_update_interval,
.maxlen = sizeof(int),
--
1.7.11.7