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Commit c9c12971 authored by Dave Chinner's avatar Dave Chinner Committed by Alex Elder
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xfs: Don't wake xfsbufd when idle 



The xfsbufd wakes every xfsbufd_centisecs (once per second by
default) for each filesystem even when the filesystem is idle.  If
the xfsbufd has nothing to do, put it into a long term sleep and
only wake it up when there is work pending (i.e. dirty buffers to
flush soon). This will make laptop power misers happy.

Signed-off-by: default avatarDave Chinner <david@fromorbit.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarAlex Elder <aelder@sgi.com>
parent 453eac8a

fs/xfs/linux-2.6/xfs_buf.c

+15 −5
Original line number Diff line number Diff line
@@ -1595,6 +1595,11 @@ xfs_buf_delwri_queue( 
		list_del(&bp->b_list);

	}



	if (list_empty(dwq)) {

		/* start xfsbufd as it is about to have something to do */

		wake_up_process(bp->b_target->bt_task);

	}



	bp->b_flags |= _XBF_DELWRI_Q;

	list_add_tail(&bp->b_list, dwq);

	bp->b_queuetime = jiffies;
@@ -1644,6 +1649,8 @@ xfsbufd_wakeup( 
	list_for_each_entry(btp, &xfs_buftarg_list, bt_list) {

		if (test_bit(XBT_FORCE_SLEEP, &btp->bt_flags))

			continue;

		if (list_empty(&btp->bt_delwrite_queue))

			continue;

		set_bit(XBT_FORCE_FLUSH, &btp->bt_flags);

		wake_up_process(btp->bt_task);

	}
@@ -1708,6 +1715,9 @@ xfsbufd( 
	set_freezable();



	do {

		long	age = xfs_buf_age_centisecs * msecs_to_jiffies(10);

		long	tout = xfs_buf_timer_centisecs * msecs_to_jiffies(10);



		if (unlikely(freezing(current))) {

			set_bit(XBT_FORCE_SLEEP, &target->bt_flags);

			refrigerator();
@@ -1715,12 +1725,12 @@ xfsbufd( 
			clear_bit(XBT_FORCE_SLEEP, &target->bt_flags);

		}



		schedule_timeout_interruptible(

			xfs_buf_timer_centisecs * msecs_to_jiffies(10));



		xfs_buf_delwri_split(target, &tmp,

				xfs_buf_age_centisecs * msecs_to_jiffies(10));

		/* sleep for a long time if there is nothing to do. */

		if (list_empty(&target->bt_delwrite_queue))

			tout = MAX_SCHEDULE_TIMEOUT;

		schedule_timeout_interruptible(tout);



		xfs_buf_delwri_split(target, &tmp, age);

		count = 0;

		while (!list_empty(&tmp)) {

			bp = list_entry(tmp.next, xfs_buf_t, b_list);