From f758eeabeb96f878c860e8f110f94ec8820822a9 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Thu, 21 Apr 2011 18:19:44 -0600 Subject: writeback: split inode_wb_list_lock into bdi_writeback.list_lock Split the global inode_wb_list_lock into a per-bdi_writeback list_lock, as it's currently the most contended lock in the system for metadata heavy workloads. It won't help for single-filesystem workloads for which we'll need the I/O-less balance_dirty_pages, but at least we can dedicate a cpu to spinning on each bdi now for larger systems. Based on earlier patches from Nick Piggin and Dave Chinner. It reduces lock contentions to 1/4 in this test case: 10 HDD JBOD, 100 dd on each disk, XFS, 6GB ram lock_stat version 0.3 ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- class name con-bounces contentions waittime-min waittime-max waittime-total acq-bounces acquisitions holdtime-min holdtime-max holdtime-total ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- vanilla 2.6.39-rc3: inode_wb_list_lock: 42590 44433 0.12 147.74 144127.35 252274 886792 0.08 121.34 917211.23 ------------------ inode_wb_list_lock 2 [] bdev_inode_switch_bdi+0x29/0x85 inode_wb_list_lock 34 [] inode_wb_list_del+0x22/0x49 inode_wb_list_lock 12893 [] __mark_inode_dirty+0x170/0x1d0 inode_wb_list_lock 10702 [] writeback_single_inode+0x16d/0x20a ------------------ inode_wb_list_lock 2 [] bdev_inode_switch_bdi+0x29/0x85 inode_wb_list_lock 19 [] inode_wb_list_del+0x22/0x49 inode_wb_list_lock 5550 [] __mark_inode_dirty+0x170/0x1d0 inode_wb_list_lock 8511 [] writeback_sb_inodes+0x10f/0x157 2.6.39-rc3 + patch: &(&wb->list_lock)->rlock: 11383 11657 0.14 151.69 40429.51 90825 527918 0.11 145.90 556843.37 ------------------------ &(&wb->list_lock)->rlock 10 [] inode_wb_list_del+0x5f/0x86 &(&wb->list_lock)->rlock 1493 [] writeback_inodes_wb+0x3d/0x150 &(&wb->list_lock)->rlock 3652 [] writeback_sb_inodes+0x123/0x16f &(&wb->list_lock)->rlock 1412 [] writeback_single_inode+0x17f/0x223 ------------------------ &(&wb->list_lock)->rlock 3 [] bdi_lock_two+0x46/0x4b &(&wb->list_lock)->rlock 6 [] inode_wb_list_del+0x5f/0x86 &(&wb->list_lock)->rlock 2061 [] __mark_inode_dirty+0x173/0x1cf &(&wb->list_lock)->rlock 2629 [] writeback_sb_inodes+0x123/0x16f hughd@google.com: fix recursive lock when bdi_lock_two() is called with new the same as old akpm@linux-foundation.org: cleanup bdev_inode_switch_bdi() comment Signed-off-by: Christoph Hellwig Signed-off-by: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Wu Fengguang --- include/linux/backing-dev.h | 2 ++ include/linux/writeback.h | 2 -- 2 files changed, 2 insertions(+), 2 deletions(-) (limited to 'include') diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h index 96f4094b706d..47feb2c4706a 100644 --- a/include/linux/backing-dev.h +++ b/include/linux/backing-dev.h @@ -57,6 +57,7 @@ struct bdi_writeback { struct list_head b_dirty; /* dirty inodes */ struct list_head b_io; /* parked for writeback */ struct list_head b_more_io; /* parked for more writeback */ + spinlock_t list_lock; /* protects the b_* lists */ }; struct backing_dev_info { @@ -106,6 +107,7 @@ int bdi_writeback_thread(void *data); int bdi_has_dirty_io(struct backing_dev_info *bdi); void bdi_arm_supers_timer(void); void bdi_wakeup_thread_delayed(struct backing_dev_info *bdi); +void bdi_lock_two(struct bdi_writeback *wb1, struct bdi_writeback *wb2); extern spinlock_t bdi_lock; extern struct list_head bdi_list; diff --git a/include/linux/writeback.h b/include/linux/writeback.h index 7df9026f7129..c2d957fb38d3 100644 --- a/include/linux/writeback.h +++ b/include/linux/writeback.h @@ -9,8 +9,6 @@ struct backing_dev_info; -extern spinlock_t inode_wb_list_lock; - /* * fs/fs-writeback.c */ -- cgit v1.2.2