From c9c129714e71c890bed1bd5b61697a896c3c2d54 Mon Sep 17 00:00:00 2001 From: Dave Chinner Date: Mon, 11 Jan 2010 11:49:59 +0000 Subject: [PATCH] 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: Dave Chinner Reviewed-by: Christoph Hellwig Signed-off-by: Alex Elder --- fs/xfs/linux-2.6/xfs_buf.c | 20 +++++++++++++++----- 1 file changed, 15 insertions(+), 5 deletions(-) diff --git a/fs/xfs/linux-2.6/xfs_buf.c b/fs/xfs/linux-2.6/xfs_buf.c index 77b8be81c769..18ae3ba8f78a 100644 --- a/fs/xfs/linux-2.6/xfs_buf.c +++ b/fs/xfs/linux-2.6/xfs_buf.c @@ -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);