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 <david@fromorbit.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Alex Elder <aelder@sgi.com>
diff --git a/fs/xfs/linux-2.6/xfs_buf.c b/fs/xfs/linux-2.6/xfs_buf.c
index 77b8be8..18ae3ba 100644
--- a/fs/xfs/linux-2.6/xfs_buf.c
+++ b/fs/xfs/linux-2.6/xfs_buf.c
@@ -1595,6 +1595,11 @@
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 @@
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 @@
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 @@
clear_bit(XBT_FORCE_SLEEP, &target->bt_flags);
}
- schedule_timeout_interruptible(
- xfs_buf_timer_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,
- xfs_buf_age_centisecs * msecs_to_jiffies(10));
-
+ xfs_buf_delwri_split(target, &tmp, age);
count = 0;
while (!list_empty(&tmp)) {
bp = list_entry(tmp.next, xfs_buf_t, b_list);