From 7747bd4bceb3079572695d3942294a6c7b265557 Mon Sep 17 00:00:00 2001 From: Dave Chinner Date: Tue, 2 Jul 2013 22:38:35 +1000 Subject: sync: don't block the flusher thread waiting on IO When sync does it's WB_SYNC_ALL writeback, it issues data Io and then immediately waits for IO completion. This is done in the context of the flusher thread, and hence completely ties up the flusher thread for the backing device until all the dirty inodes have been synced. On filesystems that are dirtying inodes constantly and quickly, this means the flusher thread can be tied up for minutes per sync call and hence badly affect system level write IO performance as the page cache cannot be cleaned quickly. We already have a wait loop for IO completion for sync(2), so cut this out of the flusher thread and delegate it to wait_sb_inodes(). Hence we can do rapid IO submission, and then wait for it all to complete. Effect of sync on fsmark before the patch: FSUse% Count Size Files/sec App Overhead ..... 0 640000 4096 35154.6 1026984 0 720000 4096 36740.3 1023844 0 800000 4096 36184.6 916599 0 880000 4096 1282.7 1054367 0 960000 4096 3951.3 918773 0 1040000 4096 40646.2 996448 0 1120000 4096 43610.1 895647 0 1200000 4096 40333.1 921048 And a single sync pass took: real 0m52.407s user 0m0.000s sys 0m0.090s After the patch, there is no impact on fsmark results, and each individual sync(2) operation run concurrently with the same fsmark workload takes roughly 7s: real 0m6.930s user 0m0.000s sys 0m0.039s IOWs, sync is 7-8x faster on a busy filesystem and does not have an adverse impact on ongoing async data write operations. Signed-off-by: Dave Chinner Reviewed-by: Jan Kara Signed-off-by: Linus Torvalds --- include/linux/writeback.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux/writeback.h') diff --git a/include/linux/writeback.h b/include/linux/writeback.h index 579a5007c696..abfe11787af3 100644 --- a/include/linux/writeback.h +++ b/include/linux/writeback.h @@ -78,6 +78,7 @@ struct writeback_control { unsigned tagged_writepages:1; /* tag-and-write to avoid livelock */ unsigned for_reclaim:1; /* Invoked from the page allocator */ unsigned range_cyclic:1; /* range_start is cyclic */ + unsigned for_sync:1; /* sync(2) WB_SYNC_ALL writeback */ }; /* -- cgit v1.2.3 From 12057841008534236e52df3d3e63e089f27c5406 Mon Sep 17 00:00:00 2001 From: Haicheng Li Date: Mon, 8 Jul 2013 16:00:11 -0700 Subject: fs/fs-writeback.c: : make wb_do_writeback() as static It's not used globally and could be static. Signed-off-by: Haicheng Li Cc: Jan Kara Cc: Wu Fengguang Cc: Kirill A. Shutemov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/writeback.h | 1 - 1 file changed, 1 deletion(-) (limited to 'include/linux/writeback.h') diff --git a/include/linux/writeback.h b/include/linux/writeback.h index abfe11787af3..e0efffafcd31 100644 --- a/include/linux/writeback.h +++ b/include/linux/writeback.h @@ -95,7 +95,6 @@ int try_to_writeback_inodes_sb_nr(struct super_block *, unsigned long nr, void sync_inodes_sb(struct super_block *); long writeback_inodes_wb(struct bdi_writeback *wb, long nr_pages, enum wb_reason reason); -long wb_do_writeback(struct bdi_writeback *wb, int force_wait); void wakeup_flusher_threads(long nr_pages, enum wb_reason reason); void inode_wait_for_writeback(struct inode *inode); -- cgit v1.2.3 From 6ce1bc86ae8b8f74095f2694732ccbab2f3849e5 Mon Sep 17 00:00:00 2001 From: Wanpeng Li Date: Mon, 8 Jul 2013 16:00:12 -0700 Subject: mm/writeback: remove wb_reason_name wb_reason_name is not used any more - remove it. Signed-off-by: Wanpeng Li Reviewed-by: Tejun Heo Reviewed-by: Fengguang Wu Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/writeback.h | 1 - 1 file changed, 1 deletion(-) (limited to 'include/linux/writeback.h') diff --git a/include/linux/writeback.h b/include/linux/writeback.h index e0efffafcd31..e1703ded543a 100644 --- a/include/linux/writeback.h +++ b/include/linux/writeback.h @@ -51,7 +51,6 @@ enum wb_reason { WB_REASON_MAX, }; -extern const char *wb_reason_name[]; /* * A control structure which tells the writeback code what to do. These are -- cgit v1.2.3 From fc6df808aaf00eed564e2e7fc0f246691363cd12 Mon Sep 17 00:00:00 2001 From: Wanpeng Li Date: Mon, 8 Jul 2013 16:00:15 -0700 Subject: mm/writeback: commit reason of WB_REASON_FORKER_THREAD mismatch name After commit 839a8e8660b6 ("writeback: replace custom worker pool implementation with unbound workqueue"), there is no bdi forker thread any more. However, WB_REASON_FORKER_THREAD is still used due to it is TPs userland visible and we won't be exposing exactly the same information with just a different name. Signed-off-by: Wanpeng Li Reviewed-by: Tejun Heo Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/writeback.h | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'include/linux/writeback.h') diff --git a/include/linux/writeback.h b/include/linux/writeback.h index e1703ded543a..4e198ca1f685 100644 --- a/include/linux/writeback.h +++ b/include/linux/writeback.h @@ -47,6 +47,12 @@ enum wb_reason { WB_REASON_LAPTOP_TIMER, WB_REASON_FREE_MORE_MEM, WB_REASON_FS_FREE_SPACE, + /* + * There is no bdi forker thread any more and works are done + * by emergency worker, however, this is TPs userland visible + * and we'll be exposing exactly the same information, + * so it has a mismatch name. + */ WB_REASON_FORKER_THREAD, WB_REASON_MAX, -- cgit v1.2.3