Messages in this thread | | | Date | Fri, 11 Sep 2009 16:39:44 +0200 | From | Jens Axboe <> | Subject | [GIT PULL] writeback rewrite |
| |
Hi Linus,
This is something that I have been working on for many months now. Originally I wanted to merge it for .31, but it was a bit too early. At least now Jan Kara and Christoph is happy with it, so it should be good to go.
Essentially this gets rid of pdflush for writeback completely. pdflush has a number of issues that largely stem from the fact that it has to work multiple queues at once. So it has to back off on congestion, which can cause queue access starvation and lumpy writeback. The latter is very apparent on many setups.
This patchset adds a thread per backing device. The thread will exit if it has been idle for too long, and will get re-created if we start seeing dirty inodes on the bdi again. Care is taken to ensure that we don't get stuck doing that.
Writeback intensive behaviour is much better. I recently generated a graph with seekwatcher of XFS writing 2 20G files using normal buffered writeout. The existing code does:
http://kernel.dk/dd-md0-xfs-pdflush.png
while with the patchset we get both a faster and more smooth writeout:
http://kernel.dk/dd-md0-xfs-flush.png
The patchset has been well tested and has been in -next for 3-4 months or so.
I have a follow-up writeback-postmerge branch with some good cleanups and performance enhancements too, but I'd like to get this in a day or two first since I didn't want to mess with the core of these bits without doing a lot more testing again. That testing can happen while this is out in the wild.
So please pull this patchset, I think we should merge it early so we have a good chance to ensure we fixup any regressions should they occur.
git://git.kernel.dk/linux-2.6-block.git writeback
Jens Axboe (7): writeback: get rid of generic_sync_sb_inodes() export writeback: move dirty inodes from super_block to backing_dev_info writeback: switch to per-bdi threads for flushing data writeback: get rid of pdflush completely writeback: add some debug inode list counters to bdi stats writeback: add name to backing_dev_info writeback: check for registered bdi in flusher add and inode dirty
block/blk-core.c | 1 + drivers/block/aoe/aoeblk.c | 1 + drivers/char/mem.c | 1 + drivers/staging/pohmelfs/inode.c | 9 +- fs/btrfs/disk-io.c | 1 + fs/buffer.c | 2 +- fs/char_dev.c | 1 + fs/configfs/inode.c | 1 + fs/fs-writeback.c | 1065 ++++++++++++++++++++++++++++---------- fs/fuse/inode.c | 1 + fs/hugetlbfs/inode.c | 1 + fs/nfs/client.c | 1 + fs/ocfs2/dlm/dlmfs.c | 1 + fs/ramfs/inode.c | 1 + fs/super.c | 5 +- fs/sync.c | 20 +- fs/sysfs/inode.c | 1 + fs/ubifs/budget.c | 16 +- fs/ubifs/super.c | 9 +- include/linux/backing-dev.h | 55 ++- include/linux/fs.h | 9 +- include/linux/writeback.h | 23 +- kernel/cgroup.c | 1 + mm/Makefile | 2 +- mm/backing-dev.c | 381 +++++++++++++- mm/page-writeback.c | 182 +------ mm/pdflush.c | 269 ---------- mm/swap_state.c | 1 + mm/vmscan.c | 2 +- 29 files changed, 1285 insertions(+), 778 deletions(-) delete mode 100644 mm/pdflush.c
-- Jens Axboe
| |