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linux/include/trace/events/writeback.h
Mel Gorman 0e093d9976 writeback: do not sleep on the congestion queue if there are no congested BDIs or if significant congestion is not being encountered in the current zone 
If congestion_wait() is called with no BDI congested, the caller will
sleep for the full timeout and this may be an unnecessary sleep.  This
patch adds a wait_iff_congested() that checks congestion and only sleeps
if a BDI is congested else, it calls cond_resched() to ensure the caller
is not hogging the CPU longer than its quota but otherwise will not sleep.

This is aimed at reducing some of the major desktop stalls reported during
IO.  For example, while kswapd is operating, it calls congestion_wait()
but it could just have been reclaiming clean page cache pages with no
congestion.  Without this patch, it would sleep for a full timeout but
after this patch, it'll just call schedule() if it has been on the CPU too
long.  Similar logic applies to direct reclaimers that are not making
enough progress.

Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-10-26 16:52:07 -07:00

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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/device.h>
#include <linux/writeback.h>
struct wb_writeback_work;
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)
),
TP_fast_assign(
strncpy(__entry->name, dev_name(bdi->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;
),
TP_printk("bdi %s: sb_dev %d:%d nr_pages=%ld sync_mode=%d "
"kupdate=%d range_cyclic=%d background=%d",
__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
)
);
#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_nothread);
DEFINE_WRITEBACK_WORK_EVENT(writeback_queue);
DEFINE_WRITEBACK_WORK_EVENT(writeback_exec);
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_thread);
DEFINE_WRITEBACK_EVENT(writeback_wake_forker_thread);
DEFINE_WRITEBACK_EVENT(writeback_bdi_register);
DEFINE_WRITEBACK_EVENT(writeback_bdi_unregister);
DEFINE_WRITEBACK_EVENT(writeback_thread_start);
DEFINE_WRITEBACK_EVENT(writeback_thread_stop);
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(int, more_io)
__field(unsigned long, older_than_this)
__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->more_io = wbc->more_io;
__entry->older_than_this = wbc->older_than_this ?
*wbc->older_than_this : 0;
__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 more=%d older=0x%lx "
"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->more_io,
__entry->older_than_this,
__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_writeback_start);
DEFINE_WBC_EVENT(wbc_writeback_written);
DEFINE_WBC_EVENT(wbc_writeback_wait);
DEFINE_WBC_EVENT(wbc_balance_dirty_start);
DEFINE_WBC_EVENT(wbc_balance_dirty_written);
DEFINE_WBC_EVENT(wbc_balance_dirty_wait);
DEFINE_WBC_EVENT(wbc_writepage);
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)
);
#endif /* _TRACE_WRITEBACK_H */
/* This part must be outside protection */
#include <trace/define_trace.h>
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