This creates a new 'reason' field in a wb_writeback_work structure, which unambiguously identifies who initiates writeback activity. A 'wb_stats' enumeration has been added to writeback.h, to enumerate the possible reasons. The 'writeback_work_class' tracepoint event class is updated to include the symbolic 'reason' in all trace events. The 'writeback_queue_io' tracepoint now takes a work object, in order to print out the 'reason' for queue_io. And the 'writeback_inodes_sbXXX' family of routines has had a wb_stats parameter added to them, so callers can specify why writeback is being started. Signed-off-by: Curt Wohlgemuth <curtw@xxxxxxxxxx> --- fs/btrfs/extent-tree.c | 3 +- fs/buffer.c | 2 +- fs/ext4/inode.c | 2 +- fs/fs-writeback.c | 46 ++++++++++++++++++++++++-------------- fs/quota/quota.c | 2 +- fs/sync.c | 4 +- fs/ubifs/budget.c | 2 +- include/linux/backing-dev.h | 3 +- include/linux/writeback.h | 29 +++++++++++++++++++---- include/trace/events/writeback.h | 37 +++++++++++++++++++++++------- mm/page-writeback.c | 8 ++++-- mm/vmscan.c | 4 +- 12 files changed, 98 insertions(+), 44 deletions(-) diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index 66bac22..5d085a9 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -3332,7 +3332,8 @@ static int shrink_delalloc(struct btrfs_trans_handle *trans, smp_mb(); nr_pages = min_t(unsigned long, nr_pages, root->fs_info->delalloc_bytes >> PAGE_CACHE_SHIFT); - writeback_inodes_sb_nr_if_idle(root->fs_info->sb, nr_pages); + writeback_inodes_sb_nr_if_idle(root->fs_info->sb, nr_pages, + WB_STAT_FS_FREE_SPACE); spin_lock(&space_info->lock); if (reserved > space_info->bytes_reserved) diff --git a/fs/buffer.c b/fs/buffer.c index 1a80b04..cfca642 100644 --- a/fs/buffer.c +++ b/fs/buffer.c @@ -285,7 +285,7 @@ static void free_more_memory(void) struct zone *zone; int nid; - wakeup_flusher_threads(1024); + wakeup_flusher_threads(1024, WB_STAT_FREE_MORE_MEM); yield(); for_each_online_node(nid) { diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 8fdc298..62aceb7 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -2200,7 +2200,7 @@ static int ext4_nonda_switch(struct super_block *sb) * start pushing delalloc when 1/2 of free blocks are dirty. */ if (free_blocks < 2 * dirty_blocks) - writeback_inodes_sb_if_idle(sb); + writeback_inodes_sb_if_idle(sb, WB_STAT_FS_FREE_SPACE); return 0; } diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index 04cf3b9..40b4029 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -41,6 +41,7 @@ struct wb_writeback_work { unsigned int for_kupdate:1; unsigned int range_cyclic:1; unsigned int for_background:1; + enum wb_stats reason; /* why was writeback initiated? */ struct list_head list; /* pending work list */ struct completion *done; /* set if the caller waits */ @@ -115,7 +116,7 @@ static void bdi_queue_work(struct backing_dev_info *bdi, static void __bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages, - bool range_cyclic) + bool range_cyclic, enum wb_stats stat) { struct wb_writeback_work *work; @@ -135,6 +136,7 @@ __bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages, work->sync_mode = WB_SYNC_NONE; work->nr_pages = nr_pages; work->range_cyclic = range_cyclic; + work->reason = stat; bdi_queue_work(bdi, work); } @@ -150,9 +152,10 @@ __bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages, * completion. Caller need not hold sb s_umount semaphore. * */ -void bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages) +void bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages, + enum wb_stats stat) { - __bdi_start_writeback(bdi, nr_pages, true); + __bdi_start_writeback(bdi, nr_pages, true, stat); } /** @@ -302,13 +305,14 @@ out: * | * +--> dequeue for IO */ -static void queue_io(struct bdi_writeback *wb, unsigned long *older_than_this) +static void queue_io(struct bdi_writeback *wb, struct wb_writeback_work *work) { int moved; assert_spin_locked(&wb->list_lock); list_splice_init(&wb->b_more_io, &wb->b_io); - moved = move_expired_inodes(&wb->b_dirty, &wb->b_io, older_than_this); - trace_writeback_queue_io(wb, older_than_this, moved); + moved = move_expired_inodes(&wb->b_dirty, &wb->b_io, + work->older_than_this); + trace_writeback_queue_io(wb, work, moved); } static int write_inode(struct inode *inode, struct writeback_control *wbc) @@ -647,11 +651,12 @@ long writeback_inodes_wb(struct bdi_writeback *wb, long nr_pages) .nr_pages = nr_pages, .sync_mode = WB_SYNC_NONE, .range_cyclic = 1, + .reason = WB_STAT_BALANCE_DIRTY, }; spin_lock(&wb->list_lock); if (list_empty(&wb->b_io)) - queue_io(wb, NULL); + queue_io(wb, &work); __writeback_inodes_wb(wb, &work); spin_unlock(&wb->list_lock); @@ -738,7 +743,7 @@ static long wb_writeback(struct bdi_writeback *wb, trace_writeback_start(wb->bdi, work); if (list_empty(&wb->b_io)) - queue_io(wb, work->older_than_this); + queue_io(wb, work); if (work->sb) progress = writeback_sb_inodes(work->sb, wb, work); else @@ -818,6 +823,7 @@ static long wb_check_background_flush(struct bdi_writeback *wb) .sync_mode = WB_SYNC_NONE, .for_background = 1, .range_cyclic = 1, + .reason = WB_STAT_BG_WRITEOUT, }; return wb_writeback(wb, &work); @@ -851,6 +857,7 @@ static long wb_check_old_data_flush(struct bdi_writeback *wb) .sync_mode = WB_SYNC_NONE, .for_kupdate = 1, .range_cyclic = 1, + .reason = WB_STAT_KUPDATE, }; return wb_writeback(wb, &work); @@ -969,7 +976,7 @@ int bdi_writeback_thread(void *data) * Start writeback of `nr_pages' pages. If `nr_pages' is zero, write back * the whole world. */ -void wakeup_flusher_threads(long nr_pages) +void wakeup_flusher_threads(long nr_pages, enum wb_stats stat) { struct backing_dev_info *bdi; @@ -982,7 +989,7 @@ void wakeup_flusher_threads(long nr_pages) list_for_each_entry_rcu(bdi, &bdi_list, bdi_list) { if (!bdi_has_dirty_io(bdi)) continue; - __bdi_start_writeback(bdi, nr_pages, false); + __bdi_start_writeback(bdi, nr_pages, false, stat); } rcu_read_unlock(); } @@ -1203,7 +1210,9 @@ static void wait_sb_inodes(struct super_block *sb) * on how many (if any) will be written, and this function does not wait * for IO completion of submitted IO. */ -void writeback_inodes_sb_nr(struct super_block *sb, unsigned long nr) +void writeback_inodes_sb_nr(struct super_block *sb, + unsigned long nr, + enum wb_stats stat) { DECLARE_COMPLETION_ONSTACK(done); struct wb_writeback_work work = { @@ -1212,6 +1221,7 @@ void writeback_inodes_sb_nr(struct super_block *sb, unsigned long nr) .tagged_writepages = 1, .done = &done, .nr_pages = nr, + .reason = stat, }; WARN_ON(!rwsem_is_locked(&sb->s_umount)); @@ -1228,9 +1238,9 @@ EXPORT_SYMBOL(writeback_inodes_sb_nr); * on how many (if any) will be written, and this function does not wait * for IO completion of submitted IO. */ -void writeback_inodes_sb(struct super_block *sb) +void writeback_inodes_sb(struct super_block *sb, enum wb_stats stat) { - return writeback_inodes_sb_nr(sb, get_nr_dirty_pages()); + return writeback_inodes_sb_nr(sb, get_nr_dirty_pages(), stat); } EXPORT_SYMBOL(writeback_inodes_sb); @@ -1241,11 +1251,11 @@ EXPORT_SYMBOL(writeback_inodes_sb); * Invoke writeback_inodes_sb if no writeback is currently underway. * Returns 1 if writeback was started, 0 if not. */ -int writeback_inodes_sb_if_idle(struct super_block *sb) +int writeback_inodes_sb_if_idle(struct super_block *sb, enum wb_stats stat) { if (!writeback_in_progress(sb->s_bdi)) { down_read(&sb->s_umount); - writeback_inodes_sb(sb); + writeback_inodes_sb(sb, stat); up_read(&sb->s_umount); return 1; } else @@ -1262,11 +1272,12 @@ EXPORT_SYMBOL(writeback_inodes_sb_if_idle); * Returns 1 if writeback was started, 0 if not. */ int writeback_inodes_sb_nr_if_idle(struct super_block *sb, - unsigned long nr) + unsigned long nr, + enum wb_stats stat) { if (!writeback_in_progress(sb->s_bdi)) { down_read(&sb->s_umount); - writeback_inodes_sb_nr(sb, nr); + writeback_inodes_sb_nr(sb, nr, stat); up_read(&sb->s_umount); return 1; } else @@ -1290,6 +1301,7 @@ void sync_inodes_sb(struct super_block *sb) .nr_pages = LONG_MAX, .range_cyclic = 0, .done = &done, + .reason = WB_STAT_SYNC, }; WARN_ON(!rwsem_is_locked(&sb->s_umount)); diff --git a/fs/quota/quota.c b/fs/quota/quota.c index b34bdb2..a3d158c 100644 --- a/fs/quota/quota.c +++ b/fs/quota/quota.c @@ -286,7 +286,7 @@ static int do_quotactl(struct super_block *sb, int type, int cmd, qid_t id, /* caller already holds s_umount */ if (sb->s_flags & MS_RDONLY) return -EROFS; - writeback_inodes_sb(sb); + writeback_inodes_sb(sb, WB_STAT_SYNC); return 0; default: return -EINVAL; diff --git a/fs/sync.c b/fs/sync.c index c98a747..b333bb4 100644 --- a/fs/sync.c +++ b/fs/sync.c @@ -43,7 +43,7 @@ static int __sync_filesystem(struct super_block *sb, int wait) if (wait) sync_inodes_sb(sb); else - writeback_inodes_sb(sb); + writeback_inodes_sb(sb, WB_STAT_SYNC); if (sb->s_op->sync_fs) sb->s_op->sync_fs(sb, wait); @@ -98,7 +98,7 @@ static void sync_filesystems(int wait) */ SYSCALL_DEFINE0(sync) { - wakeup_flusher_threads(0); + wakeup_flusher_threads(0, WB_STAT_SYNC); sync_filesystems(0); sync_filesystems(1); if (unlikely(laptop_mode)) diff --git a/fs/ubifs/budget.c b/fs/ubifs/budget.c index 315de66..9a392a0 100644 --- a/fs/ubifs/budget.c +++ b/fs/ubifs/budget.c @@ -63,7 +63,7 @@ static void shrink_liability(struct ubifs_info *c, int nr_to_write) { down_read(&c->vfs_sb->s_umount); - writeback_inodes_sb(c->vfs_sb); + writeback_inodes_sb(c->vfs_sb, WB_STAT_FS_FREE_SPACE); up_read(&c->vfs_sb->s_umount); } diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h index 3b2f9cb..9da81ef 100644 --- a/include/linux/backing-dev.h +++ b/include/linux/backing-dev.h @@ -107,7 +107,8 @@ int bdi_register(struct backing_dev_info *bdi, struct device *parent, int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev); void bdi_unregister(struct backing_dev_info *bdi); int bdi_setup_and_register(struct backing_dev_info *, char *, unsigned int); -void bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages); +void bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages, + enum wb_stats stat); void bdi_start_background_writeback(struct backing_dev_info *bdi); int bdi_writeback_thread(void *data); int bdi_has_dirty_io(struct backing_dev_info *bdi); diff --git a/include/linux/writeback.h b/include/linux/writeback.h index f1bfa12e..84d5354 100644 --- a/include/linux/writeback.h +++ b/include/linux/writeback.h @@ -50,6 +50,23 @@ enum writeback_sync_modes { }; /* + * why this writeback was initiated + */ +enum wb_stats { + /* The following are counts of pages written for a specific cause */ + WB_STAT_BALANCE_DIRTY, + WB_STAT_BG_WRITEOUT, + WB_STAT_TRY_TO_FREE_PAGES, + WB_STAT_SYNC, + WB_STAT_KUPDATE, + WB_STAT_LAPTOP_TIMER, + WB_STAT_FREE_MORE_MEM, + WB_STAT_FS_FREE_SPACE, + + WB_STAT_MAX, +}; + +/* * A control structure which tells the writeback code what to do. These are * always on the stack, and hence need no locking. They are always initialised * in a manner such that unspecified fields are set to zero. @@ -80,14 +97,16 @@ struct writeback_control { */ struct bdi_writeback; int inode_wait(void *); -void writeback_inodes_sb(struct super_block *); -void writeback_inodes_sb_nr(struct super_block *, unsigned long nr); -int writeback_inodes_sb_if_idle(struct super_block *); -int writeback_inodes_sb_nr_if_idle(struct super_block *, unsigned long nr); +void writeback_inodes_sb(struct super_block *, enum wb_stats stat); +void writeback_inodes_sb_nr(struct super_block *, unsigned long nr, + enum wb_stats stat); +int writeback_inodes_sb_if_idle(struct super_block *, enum wb_stats stat); +int writeback_inodes_sb_nr_if_idle(struct super_block *, unsigned long nr, + enum wb_stats stat); void sync_inodes_sb(struct super_block *); long writeback_inodes_wb(struct bdi_writeback *wb, long nr_pages); long wb_do_writeback(struct bdi_writeback *wb, int force_wait); -void wakeup_flusher_threads(long nr_pages); +void wakeup_flusher_threads(long nr_pages, enum wb_stats stat); /* writeback.h requires fs.h; it, too, is not included from here. */ static inline void wait_on_inode(struct inode *inode) diff --git a/include/trace/events/writeback.h b/include/trace/events/writeback.h index 6bca4cc..dbb8330 100644 --- a/include/trace/events/writeback.h +++ b/include/trace/events/writeback.h @@ -21,6 +21,18 @@ {I_REFERENCED, "I_REFERENCED"} \ ) +#define show_work_reason(reason) \ + __print_symbolic(reason, \ + {WB_STAT_BALANCE_DIRTY, "balance_dirty"}, \ + {WB_STAT_BG_WRITEOUT, "background"}, \ + {WB_STAT_TRY_TO_FREE_PAGES, "try_to_free_pages"}, \ + {WB_STAT_SYNC, "sync"}, \ + {WB_STAT_KUPDATE, "periodic"}, \ + {WB_STAT_LAPTOP_TIMER, "laptop_timer"}, \ + {WB_STAT_FREE_MORE_MEM, "free_more_memory"}, \ + {WB_STAT_FS_FREE_SPACE, "FS_free_space"} \ + ) + struct wb_writeback_work; DECLARE_EVENT_CLASS(writeback_work_class, @@ -34,6 +46,7 @@ DECLARE_EVENT_CLASS(writeback_work_class, __field(int, for_kupdate) __field(int, range_cyclic) __field(int, for_background) + __field(int, reason) ), TP_fast_assign( strncpy(__entry->name, dev_name(bdi->dev), 32); @@ -43,16 +56,18 @@ DECLARE_EVENT_CLASS(writeback_work_class, __entry->for_kupdate = work->for_kupdate; __entry->range_cyclic = work->range_cyclic; __entry->for_background = work->for_background; + __entry->reason = work->reason; ), TP_printk("bdi %s: sb_dev %d:%d nr_pages=%ld sync_mode=%d " - "kupdate=%d range_cyclic=%d background=%d", + "kupdate=%d range_cyclic=%d background=%d reason=%s", __entry->name, MAJOR(__entry->sb_dev), MINOR(__entry->sb_dev), __entry->nr_pages, __entry->sync_mode, __entry->for_kupdate, __entry->range_cyclic, - __entry->for_background + __entry->for_background, + show_work_reason(__entry->reason) ) ); #define DEFINE_WRITEBACK_WORK_EVENT(name) \ @@ -181,27 +196,31 @@ DEFINE_WBC_EVENT(wbc_writepage); TRACE_EVENT(writeback_queue_io, TP_PROTO(struct bdi_writeback *wb, - unsigned long *older_than_this, + struct wb_writeback_work *work, int moved), - TP_ARGS(wb, older_than_this, moved), + TP_ARGS(wb, work, moved), TP_STRUCT__entry( __array(char, name, 32) __field(unsigned long, older) __field(long, age) __field(int, moved) + __field(int, reason) ), TP_fast_assign( strncpy(__entry->name, dev_name(wb->bdi->dev), 32); - __entry->older = older_than_this ? *older_than_this : 0; - __entry->age = older_than_this ? - (jiffies - *older_than_this) * 1000 / HZ : -1; + __entry->older = work->older_than_this ? + *work->older_than_this : 0; + __entry->age = work->older_than_this ? + (jiffies - *work->older_than_this) * 1000 / HZ : -1; __entry->moved = moved; + __entry->reason = work->reason; ), - TP_printk("bdi %s: older=%lu age=%ld enqueue=%d", + TP_printk("bdi %s: older=%lu age=%ld enqueue=%d reason=%s", __entry->name, __entry->older, /* older_than_this in jiffies */ __entry->age, /* older_than_this in relative milliseconds */ - __entry->moved) + __entry->moved, + show_work_reason(__entry->reason)) ); TRACE_EVENT(global_dirty_state, diff --git a/mm/page-writeback.c b/mm/page-writeback.c index d196074..53c995e 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -737,8 +737,9 @@ static void balance_dirty_pages(struct address_space *mapping, */ trace_balance_dirty_start(bdi); if (bdi_nr_reclaimable > task_bdi_thresh) { - pages_written += writeback_inodes_wb(&bdi->wb, - write_chunk); + long wrote; + wrote = writeback_inodes_wb(&bdi->wb, write_chunk); + pages_written += wrote; trace_balance_dirty_written(bdi, pages_written); if (pages_written >= write_chunk) break; /* We've done our duty */ @@ -909,7 +910,8 @@ void laptop_mode_timer_fn(unsigned long data) * threshold */ if (bdi_has_dirty_io(&q->backing_dev_info)) - bdi_start_writeback(&q->backing_dev_info, nr_pages); + bdi_start_writeback(&q->backing_dev_info, nr_pages, + WB_STAT_LAPTOP_TIMER); } /* diff --git a/mm/vmscan.c b/mm/vmscan.c index 7ef6912..4a882ca 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -495,7 +495,6 @@ static pageout_t pageout(struct page *page, struct address_space *mapping, ClearPageReclaim(page); return PAGE_ACTIVATE; } - /* * Wait on writeback if requested to. This happens when * direct reclaiming a large contiguous area and the @@ -2198,7 +2197,8 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist, */ writeback_threshold = sc->nr_to_reclaim + sc->nr_to_reclaim / 2; if (total_scanned > writeback_threshold) { - wakeup_flusher_threads(laptop_mode ? 0 : total_scanned); + wakeup_flusher_threads(laptop_mode ? 0 : total_scanned, + WB_STAT_TRY_TO_FREE_PAGES); sc->may_writepage = 1; } -- 1.7.3.1 -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html