Re: [PATCH 4/5] writeback: per task dirty rate limit

Vivek Goyal
2011-08-09T17:46:32Z

On Sat, Aug 06, 2011 at 04:44:51PM +0800, Wu Fengguang wrote:

[..]
> * balance_dirty_pages() must be called by processes which are generating dirty
> * data. It looks at the number of dirty pages in the machine and will force
> * the caller to perform writeback if the system is over `vm_dirty_ratio'.
> @@ -1008,6 +1005,9 @@ static void balance_dirty_pages(struct a
> if (clear_dirty_exceeded && bdi->dirty_exceeded)
> bdi->dirty_exceeded = 0;
>
> + current->nr_dirtied = 0;
> + current->nr_dirtied_pause = ratelimit_pages(nr_dirty, dirty_thresh);
> +
> if (writeback_in_progress(bdi))
> return;
>
> @@ -1034,8 +1034,6 @@ void set_page_dirty_balance(struct page
> }
> }
>
> -static DEFINE_PER_CPU(unsigned long, bdp_ratelimits) = 0;
> -
> /**
> * balance_dirty_pages_ratelimited_nr - balance dirty memory state
> * @mapping: address_space which was dirtied
> @@ -1055,30 +1053,17 @@ void balance_dirty_pages_ratelimited_nr(
> {
> struct backing_dev_info *bdi = mapping->backing_dev_info;
> unsigned long ratelimit;
> - unsigned long *p;
>
> if (!bdi_cap_account_dirty(bdi))
> return;
>
> - ratelimit = ratelimit_pages;
> - if (mapping->backing_dev_info->dirty_exceeded)
> + ratelimit = current->nr_dirtied_pause;
> + if (bdi->dirty_exceeded)
> ratelimit = 8;

Should we make sure that ratelimit is more than 8? It could be that
ratelimit is 1 and we set it higher (just reverse of what we wanted?)

Thanks
Vivek