From: "Darrick J. Wong" Subject: Re: [RFC v4+ hot_track 03/19] vfs: add I/O frequency update function Date: Tue, 6 Nov 2012 14:45:39 -0800 Message-ID: <20121106224539.GB4255@blackbox.djwong.org> References: <1351485061-12297-1-git-send-email-zwu.kernel@gmail.com> <1351485061-12297-4-git-send-email-zwu.kernel@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org, linuxram@linux.vnet.ibm.com, viro@zeniv.linux.org.uk, david@fromorbit.com, tytso@mit.edu, cmm@us.ibm.com, wuzhy@linux.vnet.ibm.com, wenqing.lz@taobao.com To: zwu.kernel@gmail.com Return-path: Content-Disposition: inline In-Reply-To: <1351485061-12297-4-git-send-email-zwu.kernel@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On Mon, Oct 29, 2012 at 12:30:45PM +0800, zwu.kernel@gmail.com wrote: > From: Zhi Yong Wu > > Add some util helpers to update access frequencies > for one file or its range. > > Signed-off-by: Zhi Yong Wu > --- > fs/hot_tracking.c | 179 ++++++++++++++++++++++++++++++++++++++++++ > fs/hot_tracking.h | 7 ++ > include/linux/hot_tracking.h | 2 + > 3 files changed, 188 insertions(+), 0 deletions(-) > > diff --git a/fs/hot_tracking.c b/fs/hot_tracking.c > index 68591f0..0a7d9a3 100644 > --- a/fs/hot_tracking.c > +++ b/fs/hot_tracking.c > @@ -172,6 +172,137 @@ static void hot_inode_tree_exit(struct hot_info *root) > } > } > > +struct hot_inode_item > +*hot_inode_item_find(struct hot_info *root, u64 ino) > +{ > + struct hot_inode_item *he; > + int ret; > + > +again: > + spin_lock(&root->lock); > + he = radix_tree_lookup(&root->hot_inode_tree, ino); > + if (he) { > + kref_get(&he->hot_inode.refs); > + spin_unlock(&root->lock); > + return he; > + } > + spin_unlock(&root->lock); > + > + he = kmem_cache_zalloc(hot_inode_item_cachep, > + GFP_KERNEL | GFP_NOFS); > + if (!he) > + return ERR_PTR(-ENOMEM); > + > + hot_inode_item_init(he, ino, &root->hot_inode_tree); > + > + ret = radix_tree_preload(GFP_NOFS & ~__GFP_HIGHMEM); > + if (ret) { > + kmem_cache_free(hot_inode_item_cachep, he); > + return ERR_PTR(ret); > + } > + > + spin_lock(&root->lock); > + ret = radix_tree_insert(&root->hot_inode_tree, ino, he); > + if (ret == -EEXIST) { > + kmem_cache_free(hot_inode_item_cachep, he); > + spin_unlock(&root->lock); > + radix_tree_preload_end(); > + goto again; > + } > + spin_unlock(&root->lock); > + radix_tree_preload_end(); > + > + kref_get(&he->hot_inode.refs); > + return he; > +} > +EXPORT_SYMBOL_GPL(hot_inode_item_find); > + > +static struct hot_range_item > +*hot_range_item_find(struct hot_inode_item *he, > + u32 start) > +{ > + struct hot_range_item *hr; > + int ret; > + > +again: > + spin_lock(&he->lock); > + hr = radix_tree_lookup(&he->hot_range_tree, start); > + if (hr) { > + kref_get(&hr->hot_range.refs); > + spin_unlock(&he->lock); > + return hr; > + } > + spin_unlock(&he->lock); > + > + hr = kmem_cache_zalloc(hot_range_item_cachep, > + GFP_KERNEL | GFP_NOFS); > + if (!hr) > + return ERR_PTR(-ENOMEM); > + > + hot_range_item_init(hr, start, he); > + > + ret = radix_tree_preload(GFP_NOFS & ~__GFP_HIGHMEM); > + if (ret) { > + kmem_cache_free(hot_range_item_cachep, hr); > + return ERR_PTR(ret); > + } > + > + spin_lock(&he->lock); > + ret = radix_tree_insert(&he->hot_range_tree, start, hr); > + if (ret == -EEXIST) { > + kmem_cache_free(hot_range_item_cachep, hr); > + spin_unlock(&he->lock); > + radix_tree_preload_end(); > + goto again; > + } > + spin_unlock(&he->lock); > + radix_tree_preload_end(); > + > + kref_get(&hr->hot_range.refs); > + return hr; > +} > + > +/* > + * This function does the actual work of updating > + * the frequency numbers, whatever they turn out to be. > + */ > +static u64 hot_average_update(struct timespec old_atime, > + struct timespec cur_time, u64 old_avg) > +{ > + struct timespec delta_ts; > + u64 new_avg; > + u64 new_delta; > + > + delta_ts = timespec_sub(cur_time, old_atime); > + new_delta = timespec_to_ns(&delta_ts) >> FREQ_POWER; > + > + new_avg = (old_avg << FREQ_POWER) - old_avg + new_delta; > + new_avg = new_avg >> FREQ_POWER; > + > + return new_avg; > +} > + > +static void hot_freq_data_update(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->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->last_read_time, > + cur_time, > + freq_data->avg_delta_reads); I think you could just pass in a pointer to freq_data->avg_delta_{writes,reads} here... > + freq_data->last_read_time = cur_time; > + } > +} > + > /* > * Initialize kmem cache for hot_inode_item and hot_range_item. > */ > @@ -199,6 +330,54 @@ err: > EXPORT_SYMBOL_GPL(hot_cache_init); > > /* > + * Main function to update access frequency from read/writepage(s) hooks > + */ > +void hot_update_freqs(struct inode *inode, u64 start, > + u64 len, int rw) > +{ > + struct hot_info *root = inode->i_sb->s_hot_root; > + struct hot_inode_item *he; > + struct hot_range_item *hr; > + u32 cur, end; > + > + if (!root || (len == 0)) > + return; > + > + he = hot_inode_item_find(root, inode->i_ino); > + if (IS_ERR(he)) { > + WARN_ON(1); > + return; > + } > + > + spin_lock(&he->hot_inode.lock); > + hot_freq_data_update(&he->hot_inode.hot_freq_data, rw); > + spin_unlock(&he->hot_inode.lock); > + > + /* > + * Align ranges on RANGE_SIZE boundary > + * to prevent proliferation of range structs > + */ > + end = (start + len + RANGE_SIZE - 1) >> RANGE_BITS; > + for (cur = (start >> RANGE_BITS); cur < end; cur++) { Hm... start is u64, cur is u32, RANGE_BITS is 20. Doesn't this overflow if, say, I have a sparse file with blocks way out at 2^53 bytes? Also, RANGE_SIZE means that the hot tracking range granularity is 1MiB? How did you decide on that? Will we ever want to change that? > + hr = hot_range_item_find(he, cur); > + if (IS_ERR(hr)) { > + WARN_ON(1); WARN(1, "hot_range_item_find returns %d\n", PTR_ERR(hr)); ? --D > + hot_inode_item_put(he); > + return; > + } > + > + spin_lock(&hr->hot_range.lock); > + hot_freq_data_update(&hr->hot_range.hot_freq_data, rw); > + spin_unlock(&hr->hot_range.lock); > + > + hot_range_item_put(hr); > + } > + > + hot_inode_item_put(he); > +} > +EXPORT_SYMBOL_GPL(hot_update_freqs); > + > +/* > * Initialize the data structures for hot data tracking. > */ > int hot_track_init(struct super_block *sb) > diff --git a/fs/hot_tracking.h b/fs/hot_tracking.h > index e7ba121..cc4666e 100644 > --- a/fs/hot_tracking.h > +++ b/fs/hot_tracking.h > @@ -20,6 +20,13 @@ > #define FREQ_DATA_TYPE_INODE (1 << 0) > #define FREQ_DATA_TYPE_RANGE (1 << 1) > > +/* size of sub-file ranges */ > +#define RANGE_BITS 20 > +#define RANGE_SIZE (1 << RANGE_BITS) > + > +#define FREQ_POWER 4 > + > void hot_inode_item_put(struct hot_inode_item *he); > +struct hot_inode_item *hot_inode_item_find(struct hot_info *root, u64 ino); > > #endif /* __HOT_TRACKING__ */ > diff --git a/include/linux/hot_tracking.h b/include/linux/hot_tracking.h > index 4233207..e2d6028 100644 > --- a/include/linux/hot_tracking.h > +++ b/include/linux/hot_tracking.h > @@ -71,5 +71,7 @@ struct hot_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); > +extern void hot_update_freqs(struct inode *inode, u64 start, > + u64 len, int rw); > > #endif /* _LINUX_HOTTRACK_H */ > -- > 1.7.6.5 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html