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Date: Wed, 12 Sep 2012 22:31:27 +0800 From: Zhi Yong Wu <zwu.kernel@...il.com> To: linux-fsdevel@...r.kernel.org Cc: linux-kernel@...r.kernel.org, dave@...ux.vnet.ibm.com, viro@...iv.linux.org.uk, hch@....de, chris.mason@...ionio.com, cmm@...ibm.com, linuxram@...ibm.com, aneesh.kumar@...ux.vnet.ibm.com, tytso@....edu, Zhi Yong Wu <wuzhy@...ux.vnet.ibm.com> Subject: Re: [RFC 00/11] VFS: hot data tracking Sorry, forgot CCed to Ted. On Tue, Sep 11, 2012 at 10:27 PM, <zwu.kernel@...il.com> wrote: > From: Zhi Yong Wu <wuzhy@...ux.vnet.ibm.com> > > HI, folks > I have pushed the patchset to my kernel dev git tree: > git@...hub.com:wuzhy/kernel.git > > Also, you can review it via > https://github.com/wuzhy/kernel/commits/hottrack > > NOTE: > > The patchset still has a lot of bugfix and cleanup to do. It is post > out mainly to make sure it is going in the correct direction and > hope to get some helpful comments from other guys. > > TODO List: > > 1.) Need to do scalability or performance tests. > 2.) Fix up bugs. > 3.) Strictly split this patchset to keep them in order > This patchset is in RFC state, i haven't strictly split it > When it is in PATCH state, i will strictly split it and let > them in order. > 4.) Turn some Micro in to tunables > TIME_TO_KICK, and HEAT_UPDATE_DELAY > 5.) Rafactor hot_hash_is_aging() > If you just made the timeout value a timespec and compared > the _timespecs_, you would be doing a lot fewer conversions. > 6.) Cleanup some unnecessary lock protect > 7.) Add more comments to explain how to calc temperature > > Ben Chociej, Matt Lupfer and Conor Scott originally wrote this code to > be very btrfs-specific. I've taken their code and attempted to > make it more generic and integrate it at the VFS level. > > INTRODUCTION: > > Essentially, this means maintaining some key stats > (like number of reads/writes, last read/write time, frequency of > reads/writes), then distilling those numbers down to a single > "temperature" value that reflects what data is "hot," and using that > temperature to move data to SSDs. > > The long-term goal of these patches is to allow some FSs, > e.g. Btrfs to intelligently utilize SSDs in a heterogenous volume. > Incidentally, this project has been motivated by > the Project Ideas page on the Btrfs wiki. > > Of course, users are warned not to run this code outside of development > environments. These patches are EXPERIMENTAL, and as such they might eat > your data and/or memory. That said, the code should be relatively safe > when the hottrack mount option are disabled. > > MOTIVATION: > > The overall goal of enabling hot data relocation to SSD has been > motivated by the Project Ideas page on the Btrfs wiki at > <https://btrfs.wiki.kernel.org/index.php/Project_ideas>. > It will divide into two steps. VFS provide hot data tracking function > while specific FS will provide hot data relocation function. > So as the first step of this goal, it is hoped that the patchset > for hot data tracking will eventually mature into VFS. > > This is essentially the traditional cache argument: SSD is fast and > expensive; HDD is cheap but slow. ZFS, for example, can already take > advantage of SSD caching. Btrfs should also be able to take advantage of > hybrid storage without many broad, sweeping changes to existing code. > > SUMMARY: > > - Hooks in existing vfs functions to track data access frequency > > - New rbtrees for tracking access frequency of inodes and sub-file > ranges (hot_rb.c) > The relationship between super_block and rbtree is as below: > super_block->s_hotinfo.hot_inode_tree > In include/linux/fs.h, one struct hot_info s_hotinfo is added to > super_block struct. Each FS instance can find hot tracking info > s_hotinfo via its super_block. In this hot_info, it store a lot of hot > tracking info such as hot_inode_tree, inode and range hash list, etc. > > - A hash list for indexing data by its temperature (hot_hash.c) > > - A debugfs interface for dumping data from the rbtrees (hot_debugfs.c) > > - A background kthread for updating inode heat info > > - Mount options for enabling temperature tracking(-o hottrack, default mean disabled) > (hot_track.c) > > - An ioctl to retrieve the frequency information collected for a certain > file > > - Ioctls to enable/disable frequency tracking per inode. > > Usage syntax: > > root@...ian-i386:~# mount -o hottrack /dev/sdb /mnt > [ 1505.894078] device label test devid 1 transid 29 /dev/sdb > [ 1505.952977] btrfs: disk space caching is enabled > [ 1506.069678] vfs: turning on hot data tracking > root@...ian-i386:~# mount -t debugfs none /sys/kernel/debug > root@...ian-i386:~# ls -l /sys/kernel/debug/vfs_hotdata/ > total 0 > drwxr-xr-x 2 root root 0 Aug 8 04:40 sdb > root@...ian-i386:~# ls -l /sys/kernel/debug/vfs_hotdata/sdb > total 0 > -rw-r--r-- 1 root root 0 Aug 8 04:40 inode_data > -rw-r--r-- 1 root root 0 Aug 8 04:40 range_data > root@...ian-i386:~# vi /mnt/file > root@...ian-i386:~# cat /sys/kernel/debug/hot_track/sdb/inode_data > inode #279, reads 0, writes 1, avg read time 18446744073709551615, > avg write time 5251566408153596, temp 109 > root@...ian-i386:~# cat /sys/kernel/debug/hot_track/sdb/range_data > inode #279, range start 0 (range len 1048576) reads 0, writes 1, > avg read time 18446744073709551615, avg write time 1128690176623144209, temp 64 > root@...ian-i386:~# echo "hot data tracking test" >> /mnt/file > root@...ian-i386:~# cat /sys/kernel/debug/hot_track/sdb/inode_data > inode #279, reads 0, writes 2, avg read time 18446744073709551615, > avg write time 4923343766042451, temp 109 > root@...ian-i386:~# cat /sys/kernel/debug/hot_track/sdb/range_data > inode #279, range start 0 (range len 1048576) reads 0, writes 2, > avg read time 18446744073709551615, avg write time 1058147040842596150, temp 64 > root@...ian-i386:~# > > Zhi Yong Wu (11): > vfs: introduce one structure hot_info > vfs: introduce one rb tree - hot_inode_tree > vfs: introduce 2 rb tree items - inode and range > vfs: add support for updating access frequency > vfs: add one new mount option -o hottrack > vfs: add init and exit support > vfs: introduce one hash table > vfs: enable hot data tracking > vfs: fork one private kthread to update temperature info > vfs: add 3 new ioctl interfaces > vfs: add debugfs support > > fs/Makefile | 3 +- > fs/compat_ioctl.c | 8 + > fs/dcache.c | 2 + > fs/direct-io.c | 10 + > fs/hot_debugfs.c | 488 ++++++++++++++++++++++++++++++++++ > fs/hot_debugfs.h | 60 +++++ > fs/hot_hash.c | 382 ++++++++++++++++++++++++++ > fs/hot_hash.h | 112 ++++++++ > fs/hot_rb.c | 648 +++++++++++++++++++++++++++++++++++++++++++++ > fs/hot_rb.h | 81 ++++++ > fs/hot_track.c | 85 ++++++ > fs/hot_track.h | 23 ++ > fs/ioctl.c | 132 +++++++++ > fs/namespace.c | 10 + > fs/super.c | 11 + > include/linux/fs.h | 15 + > include/linux/hot_track.h | 169 ++++++++++++ > mm/filemap.c | 8 + > mm/page-writeback.c | 21 ++ > mm/readahead.c | 9 + > 20 files changed, 2276 insertions(+), 1 deletions(-) > create mode 100644 fs/hot_debugfs.c > create mode 100644 fs/hot_debugfs.h > create mode 100644 fs/hot_hash.c > create mode 100644 fs/hot_hash.h > create mode 100644 fs/hot_rb.c > create mode 100644 fs/hot_rb.h > create mode 100644 fs/hot_track.c > create mode 100644 fs/hot_track.h > create mode 100644 include/linux/hot_track.h > > -- > 1.7.6.5 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in > 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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