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Message-ID: <CAEH94Li_wvu3B5N6sKG8ALbnkN0S9WFGp=yiEd7F4VE2jkhAvg@mail.gmail.com> Date: Fri, 14 Sep 2012 15:35:40 +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 hi, all maintainers. ping? any comments are appreciated, thanks. On Wed, Sep 12, 2012 at 10:31 PM, Zhi Yong Wu <zwu.kernel@...il.com> wrote: > 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 -- 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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