[PATCH block/for-4.3] writeback: update writeback tracepoints to report cgroup

From: Tejun Heo
Date: Mon Jul 06 2015 - 15:36:55 EST

The following tracepoints are updated to report the cgroup used during
cgroup writeback.

* writeback_write_inode[_start]
* writeback_queue
* writeback_exec
* writeback_start
* writeback_written
* writeback_wait
* writeback_nowork
* writeback_wake_background
* wbc_writepage
* writeback_queue_io
* bdi_dirty_ratelimit
* balance_dirty_pages
* writeback_sb_inodes_requeue
* writeback_single_inode[_start]

Note that writeback_bdi_register is separated out from writeback_class
as reporting cgroup doesn't make sense to it. Tracepoints which take
bdi are updated to take bdi_writeback instead.

Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
---
Hello,

Will soon post this as part of a patch series of cgroup writeback
updates.

Thanks.

fs/fs-writeback.c | 14 +--
include/trace/events/writeback.h | 180 ++++++++++++++++++++++++++++++---------
mm/page-writeback.c | 6 -
3 files changed, 151 insertions(+), 49 deletions(-)

--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -176,7 +176,7 @@ static void wb_wakeup(struct bdi_writeba
static void wb_queue_work(struct bdi_writeback *wb,
struct wb_writeback_work *work)
{
- trace_writeback_queue(wb->bdi, work);
+ trace_writeback_queue(wb, work);

spin_lock_bh(&wb->work_lock);
if (!test_bit(WB_registered, &wb->state))
@@ -882,7 +882,7 @@ void wb_start_writeback(struct bdi_write
*/
work = kzalloc(sizeof(*work), GFP_ATOMIC);
if (!work) {
- trace_writeback_nowork(wb->bdi);
+ trace_writeback_nowork(wb);
wb_wakeup(wb);
return;
}
@@ -912,7 +912,7 @@ void wb_start_background_writeback(struc
* We just wake up the flusher thread. It will perform background
* writeback as soon as there is no other work to do.
*/
- trace_writeback_wake_background(wb->bdi);
+ trace_writeback_wake_background(wb);
wb_wakeup(wb);
}

@@ -1615,14 +1615,14 @@ static long wb_writeback(struct bdi_writ
} else if (work->for_background)
oldest_jif = jiffies;

- trace_writeback_start(wb->bdi, work);
+ trace_writeback_start(wb, work);
if (list_empty(&wb->b_io))
queue_io(wb, work);
if (work->sb)
progress = writeback_sb_inodes(work->sb, wb, work);
else
progress = __writeback_inodes_wb(wb, work);
- trace_writeback_written(wb->bdi, work);
+ trace_writeback_written(wb, work);

wb_update_bandwidth(wb, wb_start);

@@ -1647,7 +1647,7 @@ static long wb_writeback(struct bdi_writ
* we'll just busyloop.
*/
if (!list_empty(&wb->b_more_io)) {
- trace_writeback_wait(wb->bdi, work);
+ trace_writeback_wait(wb, work);
inode = wb_inode(wb->b_more_io.prev);
spin_lock(&inode->i_lock);
spin_unlock(&wb->list_lock);
@@ -1753,7 +1753,7 @@ static long wb_do_writeback(struct bdi_w
while ((work = get_next_work_item(wb)) != NULL) {
struct wb_completion *done = work->done;

- trace_writeback_exec(wb->bdi, work);
+ trace_writeback_exec(wb, work);

wrote += wb_writeback(wb, work);

--- a/include/trace/events/writeback.h
+++ b/include/trace/events/writeback.h
@@ -131,6 +131,66 @@ DEFINE_EVENT(writeback_dirty_inode_templ
TP_ARGS(inode, flags)
);

+#ifdef CREATE_TRACE_POINTS
+#ifdef CONFIG_CGROUP_WRITEBACK
+
+static inline size_t __trace_wb_cgroup_size(struct bdi_writeback *wb)
+{
+ return kernfs_path_len(wb->memcg_css->cgroup->kn) + 1;
+}
+
+static inline void __trace_wb_assign_cgroup(char *buf, struct bdi_writeback *wb)
+{
+ struct cgroup *cgrp = wb->memcg_css->cgroup;
+ char *path;
+
+ path = cgroup_path(cgrp, buf, kernfs_path_len(cgrp->kn) + 1);
+ WARN_ON_ONCE(path != buf);
+}
+
+static inline size_t __trace_wbc_cgroup_size(struct writeback_control *wbc)
+{
+ if (wbc->wb)
+ return __trace_wb_cgroup_size(wbc->wb);
+ else
+ return 2;
+}
+
+static inline void __trace_wbc_assign_cgroup(char *buf,
+ struct writeback_control *wbc)
+{
+ if (wbc->wb)
+ __trace_wb_assign_cgroup(buf, wbc->wb);
+ else
+ strcpy(buf, "/");
+}
+
+#else /* CONFIG_CGROUP_WRITEBACK */
+
+static inline size_t __trace_wb_cgroup_size(struct bdi_writeback *wb)
+{
+ return 2;
+}
+
+static inline void __trace_wb_assign_cgroup(char *buf, struct bdi_writeback *wb)
+{
+ strcpy(buf, "/");
+}
+
+static inline size_t __trace_wbc_cgroup_size(struct writeback_control *wbc)
+{
+ return 2;
+}
+
+static inline void __trace_wbc_assign_cgroup(char *buf,
+ struct writeback_control *wbc)
+{
+ strcpy(buf, "/");
+}
+
+#endif /* CONFIG_CGROUP_WRITEBACK */
+#endif /* CREATE_TRACE_POINTS */
+
DECLARE_EVENT_CLASS(writeback_write_inode_template,

TP_PROTO(struct inode *inode, struct writeback_control *wbc),
@@ -141,6 +201,7 @@ DECLARE_EVENT_CLASS(writeback_write_inod
__array(char, name, 32)
__field(unsigned long, ino)
__field(int, sync_mode)
+ __dynamic_array(char, cgroup, __trace_wbc_cgroup_size(wbc))
),

TP_fast_assign(
@@ -148,12 +209,14 @@ DECLARE_EVENT_CLASS(writeback_write_inod
dev_name(inode_to_bdi(inode)->dev), 32);
__entry->ino = inode->i_ino;
__entry->sync_mode = wbc->sync_mode;
+ __trace_wbc_assign_cgroup(__get_str(cgroup), wbc);
),

- TP_printk("bdi %s: ino=%lu sync_mode=%d",
+ TP_printk("bdi %s: ino=%lu sync_mode=%d cgroup=%s",
__entry->name,
__entry->ino,
- __entry->sync_mode
+ __entry->sync_mode,
+ __get_str(cgroup)
)
);

@@ -172,8 +235,8 @@ DEFINE_EVENT(writeback_write_inode_templ
);

DECLARE_EVENT_CLASS(writeback_work_class,
- TP_PROTO(struct backing_dev_info *bdi, struct wb_writeback_work *work),
- TP_ARGS(bdi, work),
+ TP_PROTO(struct bdi_writeback *wb, struct wb_writeback_work *work),
+ TP_ARGS(wb, work),
TP_STRUCT__entry(
__array(char, name, 32)
__field(long, nr_pages)
@@ -183,10 +246,11 @@ DECLARE_EVENT_CLASS(writeback_work_class
__field(int, range_cyclic)
__field(int, for_background)
__field(int, reason)
+ __dynamic_array(char, cgroup, __trace_wb_cgroup_size(wb))
),
TP_fast_assign(
strncpy(__entry->name,
- bdi->dev ? dev_name(bdi->dev) : "(unknown)", 32);
+ wb->bdi->dev ? dev_name(wb->bdi->dev) : "(unknown)", 32);
__entry->nr_pages = work->nr_pages;
__entry->sb_dev = work->sb ? work->sb->s_dev : 0;
__entry->sync_mode = work->sync_mode;
@@ -194,9 +258,10 @@ DECLARE_EVENT_CLASS(writeback_work_class
__entry->range_cyclic = work->range_cyclic;
__entry->for_background = work->for_background;
__entry->reason = work->reason;
+ __trace_wb_assign_cgroup(__get_str(cgroup), wb);
),
TP_printk("bdi %s: sb_dev %d:%d nr_pages=%ld sync_mode=%d "
- "kupdate=%d range_cyclic=%d background=%d reason=%s",
+ "kupdate=%d range_cyclic=%d background=%d reason=%s cgroup=%s",
__entry->name,
MAJOR(__entry->sb_dev), MINOR(__entry->sb_dev),
__entry->nr_pages,
@@ -204,13 +269,14 @@ DECLARE_EVENT_CLASS(writeback_work_class
__entry->for_kupdate,
__entry->range_cyclic,
__entry->for_background,
- __print_symbolic(__entry->reason, WB_WORK_REASON)
+ __print_symbolic(__entry->reason, WB_WORK_REASON),
+ __get_str(cgroup)
)
);
#define DEFINE_WRITEBACK_WORK_EVENT(name) \
DEFINE_EVENT(writeback_work_class, name, \
- TP_PROTO(struct backing_dev_info *bdi, struct wb_writeback_work *work), \
- TP_ARGS(bdi, work))
+ TP_PROTO(struct bdi_writeback *wb, struct wb_writeback_work *work), \
+ TP_ARGS(wb, work))
DEFINE_WRITEBACK_WORK_EVENT(writeback_queue);
DEFINE_WRITEBACK_WORK_EVENT(writeback_exec);
DEFINE_WRITEBACK_WORK_EVENT(writeback_start);
@@ -230,26 +296,42 @@ TRACE_EVENT(writeback_pages_written,
);

DECLARE_EVENT_CLASS(writeback_class,
- TP_PROTO(struct backing_dev_info *bdi),
- TP_ARGS(bdi),
+ TP_PROTO(struct bdi_writeback *wb),
+ TP_ARGS(wb),
TP_STRUCT__entry(
__array(char, name, 32)
+ __dynamic_array(char, cgroup, __trace_wb_cgroup_size(wb))
),
TP_fast_assign(
- strncpy(__entry->name, dev_name(bdi->dev), 32);
+ strncpy(__entry->name, dev_name(wb->bdi->dev), 32);
+ __trace_wb_assign_cgroup(__get_str(cgroup), wb);
),
- TP_printk("bdi %s",
- __entry->name
+ TP_printk("bdi %s: cgroup=%s",
+ __entry->name,
+ __get_str(cgroup)
)
);
#define DEFINE_WRITEBACK_EVENT(name) \
DEFINE_EVENT(writeback_class, name, \
- TP_PROTO(struct backing_dev_info *bdi), \
- TP_ARGS(bdi))
+ TP_PROTO(struct bdi_writeback *wb), \
+ TP_ARGS(wb))

DEFINE_WRITEBACK_EVENT(writeback_nowork);
DEFINE_WRITEBACK_EVENT(writeback_wake_background);
-DEFINE_WRITEBACK_EVENT(writeback_bdi_register);
+
+TRACE_EVENT(writeback_bdi_register,
+ TP_PROTO(struct backing_dev_info *bdi),
+ TP_ARGS(bdi),
+ TP_STRUCT__entry(
+ __array(char, name, 32)
+ ),
+ TP_fast_assign(
+ strncpy(__entry->name, dev_name(bdi->dev), 32);
+ ),
+ TP_printk("bdi %s",
+ __entry->name
+ )
+);

DECLARE_EVENT_CLASS(wbc_class,
TP_PROTO(struct writeback_control *wbc, struct backing_dev_info *bdi),
@@ -265,6 +347,7 @@ DECLARE_EVENT_CLASS(wbc_class,
__field(int, range_cyclic)
__field(long, range_start)
__field(long, range_end)
+ __dynamic_array(char, cgroup, __trace_wbc_cgroup_size(wbc))
),

TP_fast_assign(
@@ -278,11 +361,12 @@ DECLARE_EVENT_CLASS(wbc_class,
__entry->range_cyclic = wbc->range_cyclic;
__entry->range_start = (long)wbc->range_start;
__entry->range_end = (long)wbc->range_end;
+ __trace_wbc_assign_cgroup(__get_str(cgroup), wbc);
),

TP_printk("bdi %s: towrt=%ld skip=%ld mode=%d kupd=%d "
"bgrd=%d reclm=%d cyclic=%d "
- "start=0x%lx end=0x%lx",
+ "start=0x%lx end=0x%lx cgroup=%s",
__entry->name,
__entry->nr_to_write,
__entry->pages_skipped,
@@ -292,7 +376,9 @@ DECLARE_EVENT_CLASS(wbc_class,
__entry->for_reclaim,
__entry->range_cyclic,
__entry->range_start,
- __entry->range_end)
+ __entry->range_end,
+ __get_str(cgroup)
+ )
)

#define DEFINE_WBC_EVENT(name) \
@@ -312,6 +398,7 @@ TRACE_EVENT(writeback_queue_io,
__field(long, age)
__field(int, moved)
__field(int, reason)
+ __dynamic_array(char, cgroup, __trace_wb_cgroup_size(wb))
),
TP_fast_assign(
unsigned long *older_than_this = work->older_than_this;
@@ -321,13 +408,15 @@ TRACE_EVENT(writeback_queue_io,
(jiffies - *older_than_this) * 1000 / HZ : -1;
__entry->moved = moved;
__entry->reason = work->reason;
+ __trace_wb_assign_cgroup(__get_str(cgroup), wb);
),
- TP_printk("bdi %s: older=%lu age=%ld enqueue=%d reason=%s",
+ TP_printk("bdi %s: older=%lu age=%ld enqueue=%d reason=%s cgroup=%s",
__entry->name,
__entry->older, /* older_than_this in jiffies */
__entry->age, /* older_than_this in relative milliseconds */
__entry->moved,
- __print_symbolic(__entry->reason, WB_WORK_REASON)
+ __print_symbolic(__entry->reason, WB_WORK_REASON),
+ __get_str(cgroup)
)
);

@@ -381,11 +470,11 @@ TRACE_EVENT(global_dirty_state,

TRACE_EVENT(bdi_dirty_ratelimit,

- TP_PROTO(struct backing_dev_info *bdi,
+ TP_PROTO(struct bdi_writeback *wb,
unsigned long dirty_rate,
unsigned long task_ratelimit),

- TP_ARGS(bdi, dirty_rate, task_ratelimit),
+ TP_ARGS(wb, dirty_rate, task_ratelimit),

TP_STRUCT__entry(
__array(char, bdi, 32)
@@ -395,36 +484,39 @@ TRACE_EVENT(bdi_dirty_ratelimit,
__field(unsigned long, dirty_ratelimit)
__field(unsigned long, task_ratelimit)
__field(unsigned long, balanced_dirty_ratelimit)
+ __dynamic_array(char, cgroup, __trace_wb_cgroup_size(wb))
),

TP_fast_assign(
- strlcpy(__entry->bdi, dev_name(bdi->dev), 32);
- __entry->write_bw = KBps(bdi->wb.write_bandwidth);
- __entry->avg_write_bw = KBps(bdi->wb.avg_write_bandwidth);
+ strlcpy(__entry->bdi, dev_name(wb->bdi->dev), 32);
+ __entry->write_bw = KBps(wb->write_bandwidth);
+ __entry->avg_write_bw = KBps(wb->avg_write_bandwidth);
__entry->dirty_rate = KBps(dirty_rate);
- __entry->dirty_ratelimit = KBps(bdi->wb.dirty_ratelimit);
+ __entry->dirty_ratelimit = KBps(wb->dirty_ratelimit);
__entry->task_ratelimit = KBps(task_ratelimit);
__entry->balanced_dirty_ratelimit =
- KBps(bdi->wb.balanced_dirty_ratelimit);
+ KBps(wb->balanced_dirty_ratelimit);
+ __trace_wb_assign_cgroup(__get_str(cgroup), wb);
),

TP_printk("bdi %s: "
"write_bw=%lu awrite_bw=%lu dirty_rate=%lu "
"dirty_ratelimit=%lu task_ratelimit=%lu "
- "balanced_dirty_ratelimit=%lu",
+ "balanced_dirty_ratelimit=%lu cgroup=%s",
__entry->bdi,
__entry->write_bw, /* write bandwidth */
__entry->avg_write_bw, /* avg write bandwidth */
__entry->dirty_rate, /* bdi dirty rate */
__entry->dirty_ratelimit, /* base ratelimit */
__entry->task_ratelimit, /* ratelimit with position control */
- __entry->balanced_dirty_ratelimit /* the balanced ratelimit */
+ __entry->balanced_dirty_ratelimit, /* the balanced ratelimit */
+ __get_str(cgroup)
)
);

TRACE_EVENT(balance_dirty_pages,

- TP_PROTO(struct backing_dev_info *bdi,
+ TP_PROTO(struct bdi_writeback *wb,
unsigned long thresh,
unsigned long bg_thresh,
unsigned long dirty,
@@ -437,7 +529,7 @@ TRACE_EVENT(balance_dirty_pages,
long pause,
unsigned long start_time),

- TP_ARGS(bdi, thresh, bg_thresh, dirty, bdi_thresh, bdi_dirty,
+ TP_ARGS(wb, thresh, bg_thresh, dirty, bdi_thresh, bdi_dirty,
dirty_ratelimit, task_ratelimit,
dirtied, period, pause, start_time),

@@ -456,11 +548,12 @@ TRACE_EVENT(balance_dirty_pages,
__field( long, pause)
__field(unsigned long, period)
__field( long, think)
+ __dynamic_array(char, cgroup, __trace_wb_cgroup_size(wb))
),

TP_fast_assign(
unsigned long freerun = (thresh + bg_thresh) / 2;
- strlcpy(__entry->bdi, dev_name(bdi->dev), 32);
+ strlcpy(__entry->bdi, dev_name(wb->bdi->dev), 32);

__entry->limit = global_wb_domain.dirty_limit;
__entry->setpoint = (global_wb_domain.dirty_limit +
@@ -478,6 +571,7 @@ TRACE_EVENT(balance_dirty_pages,
__entry->period = period * 1000 / HZ;
__entry->pause = pause * 1000 / HZ;
__entry->paused = (jiffies - start_time) * 1000 / HZ;
+ __trace_wb_assign_cgroup(__get_str(cgroup), wb);
),


@@ -486,7 +580,7 @@ TRACE_EVENT(balance_dirty_pages,
"bdi_setpoint=%lu bdi_dirty=%lu "
"dirty_ratelimit=%lu task_ratelimit=%lu "
"dirtied=%u dirtied_pause=%u "
- "paused=%lu pause=%ld period=%lu think=%ld",
+ "paused=%lu pause=%ld period=%lu think=%ld cgroup=%s",
__entry->bdi,
__entry->limit,
__entry->setpoint,
@@ -500,7 +594,8 @@ TRACE_EVENT(balance_dirty_pages,
__entry->paused, /* ms */
__entry->pause, /* ms */
__entry->period, /* ms */
- __entry->think /* ms */
+ __entry->think, /* ms */
+ __get_str(cgroup)
)
);

@@ -514,6 +609,8 @@ TRACE_EVENT(writeback_sb_inodes_requeue,
__field(unsigned long, ino)
__field(unsigned long, state)
__field(unsigned long, dirtied_when)
+ __dynamic_array(char, cgroup,
+ __trace_wb_cgroup_size(inode_to_wb(inode)))
),

TP_fast_assign(
@@ -522,14 +619,16 @@ TRACE_EVENT(writeback_sb_inodes_requeue,
__entry->ino = inode->i_ino;
__entry->state = inode->i_state;
__entry->dirtied_when = inode->dirtied_when;
+ __trace_wb_assign_cgroup(__get_str(cgroup), inode_to_wb(inode));
),

- TP_printk("bdi %s: ino=%lu state=%s dirtied_when=%lu age=%lu",
+ TP_printk("bdi %s: ino=%lu state=%s dirtied_when=%lu age=%lu cgroup=%s",
__entry->name,
__entry->ino,
show_inode_state(__entry->state),
__entry->dirtied_when,
- (jiffies - __entry->dirtied_when) / HZ
+ (jiffies - __entry->dirtied_when) / HZ,
+ __get_str(cgroup)
)
);

@@ -585,6 +684,7 @@ DECLARE_EVENT_CLASS(writeback_single_ino
__field(unsigned long, writeback_index)
__field(long, nr_to_write)
__field(unsigned long, wrote)
+ __dynamic_array(char, cgroup, __trace_wbc_cgroup_size(wbc))
),

TP_fast_assign(
@@ -596,10 +696,11 @@ DECLARE_EVENT_CLASS(writeback_single_ino
__entry->writeback_index = inode->i_mapping->writeback_index;
__entry->nr_to_write = nr_to_write;
__entry->wrote = nr_to_write - wbc->nr_to_write;
+ __trace_wbc_assign_cgroup(__get_str(cgroup), wbc);
),

TP_printk("bdi %s: ino=%lu state=%s dirtied_when=%lu age=%lu "
- "index=%lu to_write=%ld wrote=%lu",
+ "index=%lu to_write=%ld wrote=%lu cgroup=%s",
__entry->name,
__entry->ino,
show_inode_state(__entry->state),
@@ -607,7 +708,8 @@ DECLARE_EVENT_CLASS(writeback_single_ino
(jiffies - __entry->dirtied_when) / HZ,
__entry->writeback_index,
__entry->nr_to_write,
- __entry->wrote
+ __entry->wrote,
+ __get_str(cgroup)
)
);

--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -1289,7 +1289,7 @@ static void wb_update_dirty_ratelimit(st
wb->dirty_ratelimit = max(dirty_ratelimit, 1UL);
wb->balanced_dirty_ratelimit = balanced_dirty_ratelimit;

- trace_bdi_dirty_ratelimit(wb->bdi, dirty_rate, task_ratelimit);
+ trace_bdi_dirty_ratelimit(wb, dirty_rate, task_ratelimit);
}

static void __wb_update_bandwidth(struct dirty_throttle_control *gdtc,
@@ -1683,7 +1683,7 @@ static void balance_dirty_pages(struct a
* do a reset, as it may be a light dirtier.
*/
if (pause < min_pause) {
- trace_balance_dirty_pages(bdi,
+ trace_balance_dirty_pages(wb,
sdtc->thresh,
sdtc->bg_thresh,
sdtc->dirty,
@@ -1712,7 +1712,7 @@ static void balance_dirty_pages(struct a
}

pause:
- trace_balance_dirty_pages(bdi,
+ trace_balance_dirty_pages(wb,
sdtc->thresh,
sdtc->bg_thresh,
sdtc->dirty,
--
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