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linux/include/trace/events/writeback.h
Tejun Heo 839a8e8660 writeback: replace custom worker pool implementation with unbound workqueue 
Writeback implements its own worker pool - each bdi can be associated
with a worker thread which is created and destroyed dynamically.  The
worker thread for the default bdi is always present and serves as the
"forker" thread which forks off worker threads for other bdis.

there's no reason for writeback to implement its own worker pool when
using unbound workqueue instead is much simpler and more efficient.
This patch replaces custom worker pool implementation in writeback
with an unbound workqueue.

The conversion isn't too complicated but the followings are worth
mentioning.

* bdi_writeback->last_active, task and wakeup_timer are removed.
  delayed_work ->dwork is added instead.  Explicit timer handling is
  no longer necessary.  Everything works by either queueing / modding
  / flushing / canceling the delayed_work item.

* bdi_writeback_thread() becomes bdi_writeback_workfn() which runs off
  bdi_writeback->dwork.  On each execution, it processes
  bdi->work_list and reschedules itself if there are more things to
  do.

  The function also handles low-mem condition, which used to be
  handled by the forker thread.  If the function is running off a
  rescuer thread, it only writes out limited number of pages so that
  the rescuer can serve other bdis too.  This preserves the flusher
  creation failure behavior of the forker thread.

* INIT_LIST_HEAD(&bdi->bdi_list) is used to tell
  bdi_writeback_workfn() about on-going bdi unregistration so that it
  always drains work_list even if it's running off the rescuer.  Note
  that the original code was broken in this regard.  Under memory
  pressure, a bdi could finish unregistration with non-empty
  work_list.

* The default bdi is no longer special.  It now is treated the same as
  any other bdi and bdi_cap_flush_forker() is removed.

* BDI_pending is no longer used.  Removed.

* Some tracepoints become non-applicable.  The following TPs are
  removed - writeback_nothread, writeback_wake_thread,
  writeback_wake_forker_thread, writeback_thread_start,
  writeback_thread_stop.

Everything, including devices coming and going away and rescuer
operation under simulated memory pressure, seems to work fine in my
test setup.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Cc: Jeff Moyer <jmoyer@redhat.com>
2013-04-01 19:08:06 -07:00

604 lines
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#undef TRACE_SYSTEM
#define TRACE_SYSTEM writeback
#if !defined(_TRACE_WRITEBACK_H) || defined(TRACE_HEADER_MULTI_READ)
#define _TRACE_WRITEBACK_H
#include <linux/backing-dev.h>
#include <linux/writeback.h>
#define show_inode_state(state) \
__print_flags(state, "|", \
{I_DIRTY_SYNC, "I_DIRTY_SYNC"}, \
{I_DIRTY_DATASYNC, "I_DIRTY_DATASYNC"}, \
{I_DIRTY_PAGES, "I_DIRTY_PAGES"}, \
{I_NEW, "I_NEW"}, \
{I_WILL_FREE, "I_WILL_FREE"}, \
{I_FREEING, "I_FREEING"}, \
{I_CLEAR, "I_CLEAR"}, \
{I_SYNC, "I_SYNC"}, \
{I_REFERENCED, "I_REFERENCED"} \
)
#define WB_WORK_REASON \
{WB_REASON_BACKGROUND, "background"}, \
{WB_REASON_TRY_TO_FREE_PAGES, "try_to_free_pages"}, \
{WB_REASON_SYNC, "sync"}, \
{WB_REASON_PERIODIC, "periodic"}, \
{WB_REASON_LAPTOP_TIMER, "laptop_timer"}, \
{WB_REASON_FREE_MORE_MEM, "free_more_memory"}, \
{WB_REASON_FS_FREE_SPACE, "fs_free_space"}, \
{WB_REASON_FORKER_THREAD, "forker_thread"}
struct wb_writeback_work;
TRACE_EVENT(writeback_dirty_page,
TP_PROTO(struct page *page, struct address_space *mapping),
TP_ARGS(page, mapping),
TP_STRUCT__entry (
__array(char, name, 32)
__field(unsigned long, ino)
__field(pgoff_t, index)
),
TP_fast_assign(
strncpy(__entry->name,
mapping ? dev_name(mapping->backing_dev_info->dev) : "(unknown)", 32);
__entry->ino = mapping ? mapping->host->i_ino : 0;
__entry->index = page->index;
),
TP_printk("bdi %s: ino=%lu index=%lu",
__entry->name,
__entry->ino,
__entry->index
)
);
DECLARE_EVENT_CLASS(writeback_dirty_inode_template,
TP_PROTO(struct inode *inode, int flags),
TP_ARGS(inode, flags),
TP_STRUCT__entry (
__array(char, name, 32)
__field(unsigned long, ino)
__field(unsigned long, flags)
),
TP_fast_assign(
struct backing_dev_info *bdi = inode->i_mapping->backing_dev_info;
/* may be called for files on pseudo FSes w/ unregistered bdi */
strncpy(__entry->name,
bdi->dev ? dev_name(bdi->dev) : "(unknown)", 32);
__entry->ino = inode->i_ino;
__entry->flags = flags;
),
TP_printk("bdi %s: ino=%lu flags=%s",
__entry->name,
__entry->ino,
show_inode_state(__entry->flags)
)
);
DEFINE_EVENT(writeback_dirty_inode_template, writeback_dirty_inode_start,
TP_PROTO(struct inode *inode, int flags),
TP_ARGS(inode, flags)
);
DEFINE_EVENT(writeback_dirty_inode_template, writeback_dirty_inode,
TP_PROTO(struct inode *inode, int flags),
TP_ARGS(inode, flags)
);
DECLARE_EVENT_CLASS(writeback_write_inode_template,
TP_PROTO(struct inode *inode, struct writeback_control *wbc),
TP_ARGS(inode, wbc),
TP_STRUCT__entry (
__array(char, name, 32)
__field(unsigned long, ino)
__field(int, sync_mode)
),
TP_fast_assign(
strncpy(__entry->name,
dev_name(inode->i_mapping->backing_dev_info->dev), 32);
__entry->ino = inode->i_ino;
__entry->sync_mode = wbc->sync_mode;
),
TP_printk("bdi %s: ino=%lu sync_mode=%d",
__entry->name,
__entry->ino,
__entry->sync_mode
)
);
DEFINE_EVENT(writeback_write_inode_template, writeback_write_inode_start,
TP_PROTO(struct inode *inode, struct writeback_control *wbc),
TP_ARGS(inode, wbc)
);
DEFINE_EVENT(writeback_write_inode_template, writeback_write_inode,
TP_PROTO(struct inode *inode, struct writeback_control *wbc),
TP_ARGS(inode, wbc)
);
DECLARE_EVENT_CLASS(writeback_work_class,
TP_PROTO(struct backing_dev_info *bdi, struct wb_writeback_work *work),
TP_ARGS(bdi, work),
TP_STRUCT__entry(
__array(char, name, 32)
__field(long, nr_pages)
__field(dev_t, sb_dev)
__field(int, sync_mode)
__field(int, for_kupdate)
__field(int, range_cyclic)
__field(int, for_background)
__field(int, reason)
),
TP_fast_assign(
struct device *dev = bdi->dev;
if (!dev)
dev = default_backing_dev_info.dev;
strncpy(__entry->name, dev_name(dev), 32);
__entry->nr_pages = work->nr_pages;
__entry->sb_dev = work->sb ? work->sb->s_dev : 0;
__entry->sync_mode = work->sync_mode;
__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 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,
__print_symbolic(__entry->reason, WB_WORK_REASON)
)
);
#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))
DEFINE_WRITEBACK_WORK_EVENT(writeback_queue);
DEFINE_WRITEBACK_WORK_EVENT(writeback_exec);
DEFINE_WRITEBACK_WORK_EVENT(writeback_start);
DEFINE_WRITEBACK_WORK_EVENT(writeback_written);
DEFINE_WRITEBACK_WORK_EVENT(writeback_wait);
TRACE_EVENT(writeback_pages_written,
TP_PROTO(long pages_written),
TP_ARGS(pages_written),
TP_STRUCT__entry(
__field(long, pages)
),
TP_fast_assign(
__entry->pages = pages_written;
),
TP_printk("%ld", __entry->pages)
);
DECLARE_EVENT_CLASS(writeback_class,
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
)
);
#define DEFINE_WRITEBACK_EVENT(name) \
DEFINE_EVENT(writeback_class, name, \
TP_PROTO(struct backing_dev_info *bdi), \
TP_ARGS(bdi))
DEFINE_WRITEBACK_EVENT(writeback_nowork);
DEFINE_WRITEBACK_EVENT(writeback_wake_background);
DEFINE_WRITEBACK_EVENT(writeback_bdi_register);
DEFINE_WRITEBACK_EVENT(writeback_bdi_unregister);
DECLARE_EVENT_CLASS(wbc_class,
TP_PROTO(struct writeback_control *wbc, struct backing_dev_info *bdi),
TP_ARGS(wbc, bdi),
TP_STRUCT__entry(
__array(char, name, 32)
__field(long, nr_to_write)
__field(long, pages_skipped)
__field(int, sync_mode)
__field(int, for_kupdate)
__field(int, for_background)
__field(int, for_reclaim)
__field(int, range_cyclic)
__field(long, range_start)
__field(long, range_end)
),
TP_fast_assign(
strncpy(__entry->name, dev_name(bdi->dev), 32);
__entry->nr_to_write = wbc->nr_to_write;
__entry->pages_skipped = wbc->pages_skipped;
__entry->sync_mode = wbc->sync_mode;
__entry->for_kupdate = wbc->for_kupdate;
__entry->for_background = wbc->for_background;
__entry->for_reclaim = wbc->for_reclaim;
__entry->range_cyclic = wbc->range_cyclic;
__entry->range_start = (long)wbc->range_start;
__entry->range_end = (long)wbc->range_end;
),
TP_printk("bdi %s: towrt=%ld skip=%ld mode=%d kupd=%d "
"bgrd=%d reclm=%d cyclic=%d "
"start=0x%lx end=0x%lx",
__entry->name,
__entry->nr_to_write,
__entry->pages_skipped,
__entry->sync_mode,
__entry->for_kupdate,
__entry->for_background,
__entry->for_reclaim,
__entry->range_cyclic,
__entry->range_start,
__entry->range_end)
)
#define DEFINE_WBC_EVENT(name) \
DEFINE_EVENT(wbc_class, name, \
TP_PROTO(struct writeback_control *wbc, struct backing_dev_info *bdi), \
TP_ARGS(wbc, bdi))
DEFINE_WBC_EVENT(wbc_writepage);
TRACE_EVENT(writeback_queue_io,
TP_PROTO(struct bdi_writeback *wb,
struct wb_writeback_work *work,
int 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(
unsigned long *older_than_this = work->older_than_this;
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->moved = moved;
__entry->reason = work->reason;
),
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,
__print_symbolic(__entry->reason, WB_WORK_REASON)
)
);
TRACE_EVENT(global_dirty_state,
TP_PROTO(unsigned long background_thresh,
unsigned long dirty_thresh
),
TP_ARGS(background_thresh,
dirty_thresh
),
TP_STRUCT__entry(
__field(unsigned long, nr_dirty)
__field(unsigned long, nr_writeback)
__field(unsigned long, nr_unstable)
__field(unsigned long, background_thresh)
__field(unsigned long, dirty_thresh)
__field(unsigned long, dirty_limit)
__field(unsigned long, nr_dirtied)
__field(unsigned long, nr_written)
),
TP_fast_assign(
__entry->nr_dirty = global_page_state(NR_FILE_DIRTY);
__entry->nr_writeback = global_page_state(NR_WRITEBACK);
__entry->nr_unstable = global_page_state(NR_UNSTABLE_NFS);
__entry->nr_dirtied = global_page_state(NR_DIRTIED);
__entry->nr_written = global_page_state(NR_WRITTEN);
__entry->background_thresh = background_thresh;
__entry->dirty_thresh = dirty_thresh;
__entry->dirty_limit = global_dirty_limit;
),
TP_printk("dirty=%lu writeback=%lu unstable=%lu "
"bg_thresh=%lu thresh=%lu limit=%lu "
"dirtied=%lu written=%lu",
__entry->nr_dirty,
__entry->nr_writeback,
__entry->nr_unstable,
__entry->background_thresh,
__entry->dirty_thresh,
__entry->dirty_limit,
__entry->nr_dirtied,
__entry->nr_written
)
);
#define KBps(x) ((x) << (PAGE_SHIFT - 10))
TRACE_EVENT(bdi_dirty_ratelimit,
TP_PROTO(struct backing_dev_info *bdi,
unsigned long dirty_rate,
unsigned long task_ratelimit),
TP_ARGS(bdi, dirty_rate, task_ratelimit),
TP_STRUCT__entry(
__array(char, bdi, 32)
__field(unsigned long, write_bw)
__field(unsigned long, avg_write_bw)
__field(unsigned long, dirty_rate)
__field(unsigned long, dirty_ratelimit)
__field(unsigned long, task_ratelimit)
__field(unsigned long, balanced_dirty_ratelimit)
),
TP_fast_assign(
strlcpy(__entry->bdi, dev_name(bdi->dev), 32);
__entry->write_bw = KBps(bdi->write_bandwidth);
__entry->avg_write_bw = KBps(bdi->avg_write_bandwidth);
__entry->dirty_rate = KBps(dirty_rate);
__entry->dirty_ratelimit = KBps(bdi->dirty_ratelimit);
__entry->task_ratelimit = KBps(task_ratelimit);
__entry->balanced_dirty_ratelimit =
KBps(bdi->balanced_dirty_ratelimit);
),
TP_printk("bdi %s: "
"write_bw=%lu awrite_bw=%lu dirty_rate=%lu "
"dirty_ratelimit=%lu task_ratelimit=%lu "
"balanced_dirty_ratelimit=%lu",
__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 */
)
);
TRACE_EVENT(balance_dirty_pages,
TP_PROTO(struct backing_dev_info *bdi,
unsigned long thresh,
unsigned long bg_thresh,
unsigned long dirty,
unsigned long bdi_thresh,
unsigned long bdi_dirty,
unsigned long dirty_ratelimit,
unsigned long task_ratelimit,
unsigned long dirtied,
unsigned long period,
long pause,
unsigned long start_time),
TP_ARGS(bdi, thresh, bg_thresh, dirty, bdi_thresh, bdi_dirty,
dirty_ratelimit, task_ratelimit,
dirtied, period, pause, start_time),
TP_STRUCT__entry(
__array( char, bdi, 32)
__field(unsigned long, limit)
__field(unsigned long, setpoint)
__field(unsigned long, dirty)
__field(unsigned long, bdi_setpoint)
__field(unsigned long, bdi_dirty)
__field(unsigned long, dirty_ratelimit)
__field(unsigned long, task_ratelimit)
__field(unsigned int, dirtied)
__field(unsigned int, dirtied_pause)
__field(unsigned long, paused)
__field( long, pause)
__field(unsigned long, period)
__field( long, think)
),
TP_fast_assign(
unsigned long freerun = (thresh + bg_thresh) / 2;
strlcpy(__entry->bdi, dev_name(bdi->dev), 32);
__entry->limit = global_dirty_limit;
__entry->setpoint = (global_dirty_limit + freerun) / 2;
__entry->dirty = dirty;
__entry->bdi_setpoint = __entry->setpoint *
bdi_thresh / (thresh + 1);
__entry->bdi_dirty = bdi_dirty;
__entry->dirty_ratelimit = KBps(dirty_ratelimit);
__entry->task_ratelimit = KBps(task_ratelimit);
__entry->dirtied = dirtied;
__entry->dirtied_pause = current->nr_dirtied_pause;
__entry->think = current->dirty_paused_when == 0 ? 0 :
(long)(jiffies - current->dirty_paused_when) * 1000/HZ;
__entry->period = period * 1000 / HZ;
__entry->pause = pause * 1000 / HZ;
__entry->paused = (jiffies - start_time) * 1000 / HZ;
),
TP_printk("bdi %s: "
"limit=%lu setpoint=%lu dirty=%lu "
"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",
__entry->bdi,
__entry->limit,
__entry->setpoint,
__entry->dirty,
__entry->bdi_setpoint,
__entry->bdi_dirty,
__entry->dirty_ratelimit,
__entry->task_ratelimit,
__entry->dirtied,
__entry->dirtied_pause,
__entry->paused, /* ms */
__entry->pause, /* ms */
__entry->period, /* ms */
__entry->think /* ms */
)
);
TRACE_EVENT(writeback_sb_inodes_requeue,
TP_PROTO(struct inode *inode),
TP_ARGS(inode),
TP_STRUCT__entry(
__array(char, name, 32)
__field(unsigned long, ino)
__field(unsigned long, state)
__field(unsigned long, dirtied_when)
),
TP_fast_assign(
strncpy(__entry->name,
dev_name(inode_to_bdi(inode)->dev), 32);
__entry->ino = inode->i_ino;
__entry->state = inode->i_state;
__entry->dirtied_when = inode->dirtied_when;
),
TP_printk("bdi %s: ino=%lu state=%s dirtied_when=%lu age=%lu",
__entry->name,
__entry->ino,
show_inode_state(__entry->state),
__entry->dirtied_when,
(jiffies - __entry->dirtied_when) / HZ
)
);
DECLARE_EVENT_CLASS(writeback_congest_waited_template,
TP_PROTO(unsigned int usec_timeout, unsigned int usec_delayed),
TP_ARGS(usec_timeout, usec_delayed),
TP_STRUCT__entry(
__field( unsigned int, usec_timeout )
__field( unsigned int, usec_delayed )
),
TP_fast_assign(
__entry->usec_timeout = usec_timeout;
__entry->usec_delayed = usec_delayed;
),
TP_printk("usec_timeout=%u usec_delayed=%u",
__entry->usec_timeout,
__entry->usec_delayed)
);
DEFINE_EVENT(writeback_congest_waited_template, writeback_congestion_wait,
TP_PROTO(unsigned int usec_timeout, unsigned int usec_delayed),
TP_ARGS(usec_timeout, usec_delayed)
);
DEFINE_EVENT(writeback_congest_waited_template, writeback_wait_iff_congested,
TP_PROTO(unsigned int usec_timeout, unsigned int usec_delayed),
TP_ARGS(usec_timeout, usec_delayed)
);
DECLARE_EVENT_CLASS(writeback_single_inode_template,
TP_PROTO(struct inode *inode,
struct writeback_control *wbc,
unsigned long nr_to_write
),
TP_ARGS(inode, wbc, nr_to_write),
TP_STRUCT__entry(
__array(char, name, 32)
__field(unsigned long, ino)
__field(unsigned long, state)
__field(unsigned long, dirtied_when)
__field(unsigned long, writeback_index)
__field(long, nr_to_write)
__field(unsigned long, wrote)
),
TP_fast_assign(
strncpy(__entry->name,
dev_name(inode_to_bdi(inode)->dev), 32);
__entry->ino = inode->i_ino;
__entry->state = inode->i_state;
__entry->dirtied_when = inode->dirtied_when;
__entry->writeback_index = inode->i_mapping->writeback_index;
__entry->nr_to_write = nr_to_write;
__entry->wrote = nr_to_write - wbc->nr_to_write;
),
TP_printk("bdi %s: ino=%lu state=%s dirtied_when=%lu age=%lu "
"index=%lu to_write=%ld wrote=%lu",
__entry->name,
__entry->ino,
show_inode_state(__entry->state),
__entry->dirtied_when,
(jiffies - __entry->dirtied_when) / HZ,
__entry->writeback_index,
__entry->nr_to_write,
__entry->wrote
)
);
DEFINE_EVENT(writeback_single_inode_template, writeback_single_inode_start,
TP_PROTO(struct inode *inode,
struct writeback_control *wbc,
unsigned long nr_to_write),
TP_ARGS(inode, wbc, nr_to_write)
);
DEFINE_EVENT(writeback_single_inode_template, writeback_single_inode,
TP_PROTO(struct inode *inode,
struct writeback_control *wbc,
unsigned long nr_to_write),
TP_ARGS(inode, wbc, nr_to_write)
);
#endif /* _TRACE_WRITEBACK_H */
/* This part must be outside protection */
#include <trace/define_trace.h>
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