linux-kernel - [PATCH v1 hot_track 08/16] vfs: add aging function

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Date:	Fri, 16 Nov 2012 17:51:10 +0800
From:	zwu.kernel@...il.com
To:	linux-fsdevel@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, viro@...iv.linux.org.uk,
	Zhi Yong Wu <wuzhy@...ux.vnet.ibm.com>
Subject: [PATCH v1 hot_track 08/16] vfs: add aging function

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

Signed-off-by: Zhi Yong Wu <wuzhy@...ux.vnet.ibm.com>
---
 fs/hot_tracking.c |   49 +++++++++++++++++++++++++++++++++++++++++++++++++
 fs/hot_tracking.h |    6 ++++++
 2 files changed, 55 insertions(+), 0 deletions(-)

diff --git a/fs/hot_tracking.c b/fs/hot_tracking.c
index 446fbd4..304028d 100644
--- a/fs/hot_tracking.c
+++ b/fs/hot_tracking.c
@@ -385,6 +385,24 @@ static u32 hot_temp_calc(struct hot_freq_data *freq_data)
 	return result;
 }
 
+static bool hot_is_obsolete(struct hot_freq_data *freq_data)
+{
+	int ret = 0;
+	struct timespec ckt = current_kernel_time();
+
+	u64 cur_time = timespec_to_ns(&ckt);
+	u64 last_read_ns =
+		(cur_time - timespec_to_ns(&freq_data->last_read_time));
+	u64 last_write_ns =
+		(cur_time - timespec_to_ns(&freq_data->last_write_time));
+	u64 kick_ns =  TIME_TO_KICK * NSEC_PER_SEC;
+
+	if ((last_read_ns > kick_ns) && (last_write_ns > kick_ns))
+		ret = 1;
+
+	return ret;
+}
+
 /*
  * Calculate a new temperature and, if necessary,
  * move the list_head corresponding to this inode or range
@@ -452,6 +470,37 @@ static void hot_map_update(struct hot_freq_data *freq_data,
 	}
 }
 
+/* Update temperatures for each range item for aging purposes */
+static void hot_range_update(struct hot_inode_item *he,
+					struct hot_info *root)
+{
+	struct rb_node *node;
+	struct hot_comm_item *ci;
+	struct hot_range_item *hr;
+	bool obsolete;
+
+	spin_lock(&he->lock);
+	node = rb_first(&he->hot_range_tree.map);
+	while (node) {
+		ci = rb_entry(node, struct hot_comm_item, rb_node);
+		hr = container_of(ci, struct hot_range_item, hot_range);
+		kref_get(&hr->hot_range.refs);
+		hot_map_update(&hr->hot_range.hot_freq_data, root);
+
+		spin_lock(&hr->hot_range.lock);
+		obsolete = hot_is_obsolete(
+				&hr->hot_range.hot_freq_data);
+		spin_unlock(&hr->hot_range.lock);
+
+		node = rb_next(node);
+
+		hot_range_item_put(hr);
+		if (obsolete)
+			hot_range_item_put(hr);
+	}
+	spin_unlock(&he->lock);
+}
+
 /*
  * Initialize inode and range map info.
  */
diff --git a/fs/hot_tracking.h b/fs/hot_tracking.h
index f33066f..46d068a 100644
--- a/fs/hot_tracking.h
+++ b/fs/hot_tracking.h
@@ -24,6 +24,12 @@
 #define RANGE_SIZE (1 << RANGE_BITS)
 #define FREQ_POWER 4
 
+/*
+ * time to quit keeping track of
+ * tracking data (seconds)
+ */
+#define TIME_TO_KICK 300
+
 /* NRR/NRW heat unit = 2^X accesses */
 #define NRR_MULTIPLIER_POWER 20 /* NRR - number of reads since mount */
 #define NRR_COEFF_POWER 0
-- 
1.7.6.5

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