From: Zhi Yong Wu Subject: Re: [RFC v4+ hot_track 03/19] vfs: add I/O frequency update function Date: Wed, 7 Nov 2012 16:27:05 +0800 Message-ID: References: <1351485061-12297-1-git-send-email-zwu.kernel@gmail.com> <1351485061-12297-4-git-send-email-zwu.kernel@gmail.com> <20121106224539.GB4255@blackbox.djwong.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 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: "Darrick J. Wong" Return-path: Received: from mail-bk0-f46.google.com ([209.85.214.46]:37509 "EHLO mail-bk0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750825Ab2KGI1I (ORCPT ); Wed, 7 Nov 2012 03:27:08 -0500 In-Reply-To: <20121106224539.GB4255@blackbox.djwong.org> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Wed, Nov 7, 2012 at 6:45 AM, Darrick J. Wong wrote: > 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... why? > >> + 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? ah, good catch, thanks. > > Also, RANGE_SIZE means that the hot tracking range granularity is 1MiB? How yes. > did you decide on that? Will we ever want to change that? It is one assumption, do you think 1 MB is not appropriate? Do you mean to add one proc file interface for it? > >> + 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)); ? OK, done. > > --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 -- Regards, Zhi Yong Wu