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Message-ID: <20121106233011.GC4255@blackbox.djwong.org>
Date: Tue, 6 Nov 2012 15:30:11 -0800
From: "Darrick J. Wong" <darrick.wong@...cle.com>
To: zwu.kernel@...il.com
Cc: linux-fsdevel@...r.kernel.org, linux-ext4@...r.kernel.org,
linux-btrfs@...r.kernel.org, linux-kernel@...r.kernel.org,
linuxram@...ux.vnet.ibm.com, viro@...iv.linux.org.uk,
david@...morbit.com, tytso@....edu, cmm@...ibm.com,
wuzhy@...ux.vnet.ibm.com, wenqing.lz@...bao.com
Subject: Re: [RFC v4+ hot_track 10/19] vfs: introduce hot func register
framework
On Mon, Oct 29, 2012 at 12:30:52PM +0800, zwu.kernel@...il.com wrote:
> From: Zhi Yong Wu <wuzhy@...ux.vnet.ibm.com>
>
> Introduce one framwork to enable that specific FS
> can register its own hot tracking functions.
>
> Signed-off-by: Zhi Yong Wu <wuzhy@...ux.vnet.ibm.com>
> ---
> fs/hot_tracking.c | 78 ++++++++++++++++++++++++++++++++++++++----
> include/linux/hot_tracking.h | 25 +++++++++++++
> 2 files changed, 96 insertions(+), 7 deletions(-)
>
> diff --git a/fs/hot_tracking.c b/fs/hot_tracking.c
> index 0ef9cad..c6c6138 100644
> --- a/fs/hot_tracking.c
> +++ b/fs/hot_tracking.c
> @@ -24,6 +24,9 @@
> #include <linux/limits.h>
> #include "hot_tracking.h"
>
> +static DEFINE_SPINLOCK(hot_func_list_lock);
> +static LIST_HEAD(hot_func_list);
> +
> /* 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;
> @@ -305,20 +308,23 @@ static u64 hot_average_update(struct timespec old_atime,
> return new_avg;
> }
>
> -static void hot_freq_data_update(struct hot_freq_data *freq_data, bool write)
> +static void hot_freq_data_update(struct hot_info *root,
> + struct hot_freq_data *freq_data, bool write)
> {
> struct timespec cur_time = current_kernel_time();
>
> if (write) {
> freq_data->nr_writes += 1;
> - freq_data->avg_delta_writes = hot_average_update(
> + freq_data->avg_delta_writes =
> + root->hot_func_type->ops.hot_rw_freq_calc_fn(
> 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;
> - freq_data->avg_delta_reads = hot_average_update(
> + freq_data->avg_delta_reads =
> + root->hot_func_type->ops.hot_rw_freq_calc_fn(
> freq_data->last_read_time,
> cur_time,
> freq_data->avg_delta_reads);
> @@ -430,7 +436,7 @@ static void hot_map_array_update(struct hot_freq_data *freq_data,
> struct hot_comm_item *comm_item;
> struct hot_inode_item *he;
> struct hot_range_item *hr;
> - u32 temp = hot_temp_calc(freq_data);
> + u32 temp = root->hot_func_type->ops.hot_temp_calc_fn(freq_data);
> u8 a_temp = temp >> (32 - HEAT_MAP_BITS);
> u8 b_temp = freq_data->last_temp >> (32 - HEAT_MAP_BITS);
>
> @@ -511,7 +517,7 @@ static void hot_range_update(struct hot_inode_item *he,
> &hr_nodes[i]->hot_range.hot_freq_data, root);
>
> spin_lock(&hr_nodes[i]->hot_range.lock);
> - obsolete = hot_is_obsolete(
> + obsolete = root->hot_func_type->ops.hot_is_obsolete_fn(
> &hr_nodes[i]->hot_range.hot_freq_data);
> spin_unlock(&hr_nodes[i]->hot_range.lock);
>
> @@ -668,7 +674,7 @@ void hot_update_freqs(struct inode *inode, u64 start,
> }
>
> spin_lock(&he->hot_inode.lock);
> - hot_freq_data_update(&he->hot_inode.hot_freq_data, rw);
> + hot_freq_data_update(root, &he->hot_inode.hot_freq_data, rw);
> spin_unlock(&he->hot_inode.lock);
>
> /*
> @@ -685,7 +691,7 @@ void hot_update_freqs(struct inode *inode, u64 start,
> }
>
> spin_lock(&hr->hot_range.lock);
> - hot_freq_data_update(&hr->hot_range.hot_freq_data, rw);
> + hot_freq_data_update(root, &hr->hot_range.hot_freq_data, rw);
> spin_unlock(&hr->hot_range.lock);
>
> hot_range_item_put(hr);
> @@ -695,6 +701,61 @@ void hot_update_freqs(struct inode *inode, u64 start,
> }
> EXPORT_SYMBOL_GPL(hot_update_freqs);
>
> +static struct hot_func_type hot_func_def = {
> + .hot_func_name = "hot_type_def",
> + .ops = {
> + .hot_rw_freq_calc_fn = hot_average_update,
> + .hot_temp_calc_fn = hot_temp_calc,
> + .hot_is_obsolete_fn = hot_is_obsolete,
> + },
> +};
If these hot_ops are per-filesystem, why not just embed a struct hot_func_ops
inside of struct file_system_type? That eliminates this _get function,
collision avoidance, etc. You can fill in NULL function pointers in
hot_track_init (or just code around them).
--D
> +
> +static struct hot_func_type *hot_func_get(const char *name)
> +{
> + struct hot_func_type *f, *h = &hot_func_def;
> +
> + spin_lock(&hot_func_list_lock);
> + list_for_each_entry(f, &hot_func_list, list) {
> + if (!strcmp(f->hot_func_name, name))
> + h = f;
> + }
> + spin_unlock(&hot_func_list_lock);
> +
> + return h;
> +}
> +
> +int hot_func_register(struct hot_func_type *h)
> +{
> + struct hot_func_type *f, *t = NULL;
> +
> + /* register, don't allow duplicate names */
> + spin_lock(&hot_func_list_lock);
> + list_for_each_entry(f, &hot_func_list, list) {
> + if (!strcmp(f->hot_func_name, h->hot_func_name))
> + t = f;
> + }
> +
> + if (t) {
> + spin_unlock(&hot_func_list_lock);
> + return -EBUSY;
> + }
> +
> + list_add_tail(&h->list, &hot_func_list);
> + spin_unlock(&hot_func_list_lock);
> +
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(hot_func_register);
> +
> +void hot_func_unregister(struct hot_func_type *h)
> +{
> + /* unregister */
> + spin_lock(&hot_func_list_lock);
> + list_del_init(&h->list);
> + spin_unlock(&hot_func_list_lock);
> +}
> +EXPORT_SYMBOL_GPL(hot_func_unregister);
> +
> /*
> * Initialize the data structures for hot data tracking.
> */
> @@ -714,6 +775,9 @@ int hot_track_init(struct super_block *sb)
> hot_inode_tree_init(root);
> hot_map_array_init(root);
>
> + /* Get hot func type */
> + root->hot_func_type = hot_func_get(sb->s_type->name);
> +
> root->update_wq = alloc_workqueue(
> "hot_update_wq", WQ_NON_REENTRANT, 0);
> if (!root->update_wq) {
> diff --git a/include/linux/hot_tracking.h b/include/linux/hot_tracking.h
> index 2ee0d02..3941052 100644
> --- a/include/linux/hot_tracking.h
> +++ b/include/linux/hot_tracking.h
> @@ -23,6 +23,8 @@
> #define HEAT_MAP_BITS 8
> #define HEAT_MAP_SIZE (1 << HEAT_MAP_BITS)
>
> +#define HOT_NAME_MAX 16
> +
> /*
> * A frequency data struct holds values that are used to
> * determine temperature of files and file ranges. These structs
> @@ -73,6 +75,25 @@ struct hot_range_item {
> u32 len; /* length in bytes */
> };
>
> +typedef u64 (hot_rw_freq_calc_fn) (struct timespec old_atime,
> + struct timespec cur_time, u64 old_avg);
> +typedef u32 (hot_temp_calc_fn) (struct hot_freq_data *freq_data);
> +typedef bool (hot_is_obsolete_fn) (struct hot_freq_data *freq_data);
> +
> +struct hot_func_ops {
> + hot_rw_freq_calc_fn *hot_rw_freq_calc_fn;
> + hot_temp_calc_fn *hot_temp_calc_fn;
> + hot_is_obsolete_fn *hot_is_obsolete_fn;
> +};
> +
> +/* identifies an hot func type */
> +struct hot_func_type {
> + char hot_func_name[HOT_NAME_MAX];
> + /* fields provided by specific FS */
> + struct hot_func_ops ops;
> + struct list_head list;
> +};
> +
> struct hot_info {
> struct radix_tree_root hot_inode_tree;
> spinlock_t lock; /*protect inode tree */
> @@ -85,6 +106,7 @@ struct hot_info {
>
> struct workqueue_struct *update_wq;
> struct delayed_work update_work;
> + struct hot_func_type *hot_func_type;
> };
>
> extern void __init hot_cache_init(void);
> @@ -93,4 +115,7 @@ extern void hot_track_exit(struct super_block *sb);
> extern void hot_update_freqs(struct inode *inode, u64 start,
> u64 len, int rw);
>
> +extern int hot_func_register(struct hot_func_type *h);
> +extern void hot_func_unregister(struct hot_func_type *h);
> +
> #endif /* _LINUX_HOTTRACK_H */
> --
> 1.7.6.5
>
> --
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