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>
Acked-by: Jan Kara <jack@xxxxxxx>
---
Changelog since v1:
- Added a "enum wb_stats" parameter to writeback_inodes_wb(),
instead of assuming that the reason for this is always
WB_STAT_BALANCE_DIRTY
- Removed change around the call to writeback_inodes_wb() in
balance_dirty_pages(), meant for patch 2/2 in this series.
fs/btrfs/extent-tree.c | 3 +-
fs/buffer.c | 2 +-
fs/ext4/inode.c | 2 +-
fs/fs-writeback.c | 49 ++++++++++++++++++++++++--------------
fs/quota/quota.c | 2 +-
fs/sync.c | 4 +-
fs/ubifs/budget.c | 2 +-
include/linux/backing-dev.h | 3 +-
include/linux/writeback.h | 33 +++++++++++++++++++++----
include/trace/events/writeback.h | 37 +++++++++++++++++++++-------
mm/backing-dev.c | 3 +-
mm/page-writeback.c | 6 +++-
mm/vmscan.c | 4 +-
13 files changed, 104 insertions(+), 46 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..70aa19d 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)
@@ -641,17 +645,19 @@ static long __writeback_inodes_wb(struct bdi_writeback *wb,
return wrote;
}
-long writeback_inodes_wb(struct bdi_writeback *wb, long nr_pages)
+long writeback_inodes_wb(struct bdi_writeback *wb, long nr_pages,
+ enum wb_stats stat)
{
struct wb_writeback_work work = {
.nr_pages = nr_pages,
.sync_mode = WB_SYNC_NONE,
.range_cyclic = 1,
+ .reason = stat,
};
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 +744,7 @@ 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 +824,7 @@ 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 +858,7 @@ 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 +977,7 @@ 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 +990,7 @@ 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 +1211,9 @@ 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 +1222,7 @@ 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 +1239,9 @@ 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 +1252,11 @@ 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 +1273,12 @@ 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 +1302,7 @@ 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..a70696d 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -50,6 +50,24 @@ 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_FORKER_THREAD,
+
+ 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 +98,17 @@ 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 writeback_inodes_wb(struct bdi_writeback *wb, long nr_pages,
+ enum wb_stats stat);
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/backing-dev.c b/mm/backing-dev.c
index d6edf8d..63b3b29 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -456,7 +456,8 @@ static int bdi_forker_thread(void *ptr)
* the bdi from the thread. Hopefully 1024 is
* large enough for efficient IO.
*/
- writeback_inodes_wb(&bdi->wb, 1024);
+ writeback_inodes_wb(&bdi->wb, 1024,
+ WB_STAT_FORKER_THREAD);
} else {
/*
* The spinlock makes sure we do not lose
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index d196074..5503461 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -738,7 +738,8 @@ 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);
+ write_chunk,
+ WB_STAT_BALANCE_DIRTY);
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
--
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