> From 595677f8efcaa0d9f675bf74a7048739323afd06 Mon Sep 17 00:00:00 2001
> From: Jan Kara <jack@xxxxxxx>
> Date: Wed, 19 Oct 2011 13:44:46 +0200
> Subject: [PATCH] writeback: Retry kupdate work early if we need to retry some inode writeback
>
> In case we could not do any writeback for some inodes, trigger next kupdate
> work early so that writeback on these inodes is not delayed for the whole
> dirty_writeback_interval.
Looks good, too.
> Signed-off-by: Jan Kara <jack@xxxxxxx>
> ---
> fs/fs-writeback.c | 25 ++++++++++++++++++-------
> 1 files changed, 18 insertions(+), 7 deletions(-)
>
> diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
> index 8314241..e48da04 100644
> --- a/fs/fs-writeback.c
> +++ b/fs/fs-writeback.c
> @@ -701,6 +701,7 @@ static long wb_writeback(struct bdi_writeback *wb,
> unsigned long oldest_jif;
> struct inode *inode;
> long progress;
> + long total_progress = 0;
>
> oldest_jif = jiffies;
> work->older_than_this = &oldest_jif;
> @@ -750,6 +751,7 @@ static long wb_writeback(struct bdi_writeback *wb,
> else
> progress = __writeback_inodes_wb(wb, work);
> trace_writeback_written(wb->bdi, work);
> + total_progress += progress;
>
> wb_update_bandwidth(wb, wb_start);
>
> @@ -783,7 +785,7 @@ static long wb_writeback(struct bdi_writeback *wb,
> }
> spin_unlock(&wb->list_lock);
>
> - return nr_pages - work->nr_pages;
> + return total_progress;
> }
>
> /*
> @@ -845,7 +847,7 @@ static long wb_check_old_data_flush(struct bdi_writeback *wb)
>
> expired = wb->last_old_flush +
> msecs_to_jiffies(dirty_writeback_interval * 10);
> - if (time_before(jiffies, expired))
> + if (time_before(jiffies, expired) && list_empty(&wb->b_more_io_wait))
> return 0;
>
> wb->last_old_flush = jiffies;
> @@ -915,7 +917,11 @@ int bdi_writeback_thread(void *data)
> {
> struct bdi_writeback *wb = data;
> struct backing_dev_info *bdi = wb->bdi;
> - long pages_written;
> + long progress;
I'd like to separate out the pages_written=>progress changes,
which will make two more clear patches.
Thanks,
Fengguang
> + unsigned int pause = 1;
> + unsigned int max_pause = dirty_writeback_interval ?
> + msecs_to_jiffies(dirty_writeback_interval * 10) :
> + HZ;
>
> current->flags |= PF_SWAPWRITE;
> set_freezable();
> @@ -935,12 +941,14 @@ int bdi_writeback_thread(void *data)
> */
> del_timer(&wb->wakeup_timer);
>
> - pages_written = wb_do_writeback(wb, 0);
> + progress = wb_do_writeback(wb, 0);
>
> trace_writeback_pages_written(pages_written);
>
> - if (pages_written)
> + if (progress) {
> wb->last_active = jiffies;
> + pause = 1;
> + }
>
> set_current_state(TASK_INTERRUPTIBLE);
> if (!list_empty(&bdi->work_list) || kthread_should_stop()) {
> @@ -948,8 +956,11 @@ int bdi_writeback_thread(void *data)
> continue;
> }
>
> - if (wb_has_dirty_io(wb) && dirty_writeback_interval)
> - schedule_timeout(msecs_to_jiffies(dirty_writeback_interval * 10));
> + if (!list_empty(&wb->b_more_io_wait) && pause < max_pause) {
> + schedule_timeout(pause);
> + pause <<= 1;
> + } else if (wb_has_dirty_io(wb) && dirty_writeback_interval)
> + schedule_timeout(max_pause);
> else {
> /*
> * We have nothing to do, so can go sleep without any
> --
> 1.7.1
>
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