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 --- mm/rmap.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'mm/rmap.c') diff --git a/mm/rmap.c b/mm/rmap.c index 0eb463ea88d..d04e36a7cc9 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -32,11 +32,11 @@ * mmlist_lock (in mmput, drain_mmlist and others) * mapping->private_lock (in __set_page_dirty_buffers) * inode->i_lock (in set_page_dirty's __mark_inode_dirty) - * inode_wb_list_lock (in set_page_dirty's __mark_inode_dirty) + * bdi.wb->list_lock (in set_page_dirty's __mark_inode_dirty) * sb_lock (within inode_lock in fs/fs-writeback.c) * mapping->tree_lock (widely used, in set_page_dirty, * in arch-dependent flush_dcache_mmap_lock, - * within inode_wb_list_lock in __sync_single_inode) + * within bdi.wb->list_lock in __sync_single_inode) * * (code doesn't rely on that order so it could be switched around) * ->tasklist_lock -- cgit v1.2.3-70-g09d2