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Date: Wed, 7 Nov 2012 16:34:35 +0800
From: Zhi Yong Wu <zwu.kernel@...il.com>
To: "Darrick J. Wong" <darrick.wong@...cle.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 Wed, Nov 7, 2012 at 7:30 AM, Darrick J. Wong <darrick.wong@...cle.com> wrote:
> 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,
this _get function is very small, only some loc, if hot_func_ops is
embedded in struct file_system_type, i am afraid to introduce some
regressions....
> collision avoidance, etc. You can fill in NULL function pointers in
fill in NULL func pointer? why?
> 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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>> the body of a message to majordomo@...r.kernel.org
>> More majordomo info at http://vger.kernel.org/majordomo-info.html
--
Regards,
Zhi Yong Wu
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