Hi Wu,
> Subject: writeback: sync expired inodes first in background writeback
> From: Wu Fengguang <fengguang.wu@xxxxxxxxx>
> Date: Wed Jul 21 20:11:53 CST 2010
>
> A background flush work may run for ever. So it's reasonable for it to
> mimic the kupdate behavior of syncing old/expired inodes first.
>
> The policy is
> - enqueue all newly expired inodes at each queue_io() time
> - enqueue all dirty inodes if there are no more expired inodes to sync
>
> This will help reduce the number of dirty pages encountered by page
> reclaim, eg. the pageout() calls. Normally older inodes contain older
> dirty pages, which are more close to the end of the LRU lists. So
> syncing older inodes first helps reducing the dirty pages reached by
> the page reclaim code.
>
> CC: Jan Kara <jack@xxxxxxx>
> Signed-off-by: Wu Fengguang <fengguang.wu@xxxxxxxxx>
> ---
> fs/fs-writeback.c | 23 ++++++++++++++++++-----
> 1 file changed, 18 insertions(+), 5 deletions(-)
>
> --- linux-next.orig/fs/fs-writeback.c 2010-07-26 20:19:01.000000000 +0800
> +++ linux-next/fs/fs-writeback.c 2010-07-26 21:10:42.000000000 +0800
> @@ -217,14 +217,14 @@ static void move_expired_inodes(struct l
> struct writeback_control *wbc)
> {
> unsigned long expire_interval = 0;
> - unsigned long older_than_this;
> + unsigned long older_than_this = 0; /* reset to kill gcc warning */
Maybe I am rather late.
Nitpick.
uninitialized_var is consistent. :)
I haven't followed up this patch series. but his patch series is a fundamental way
to go for reducing pageout.
--
Kind regards,
Minchan Kim
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