On Fri 22-05-15 17:13:49, Tejun Heo wrote:
> bdi->min/max_ratio are user-configurable per-bdi knobs which regulate
> dirty limit of each bdi. For cgroup writeback, they need to be
> further distributed across wb's (bdi_writeback's) belonging to the
> configured bdi.
>
> This patch introduces wb_min_max_ratio() which distributes
> bdi->min/max_ratio according to a wb's proportion in the total active
> bandwidth of its bdi.
>
> v2: Update wb_min_max_ratio() to fix a bug where both min and max were
> assigned the min value and avoid calculations when possible.
>
> Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
> Cc: Jens Axboe <axboe@xxxxxxxxx>
> Cc: Jan Kara <jack@xxxxxxx>
Looks good. You can add:
Reviewed-by: Jan Kara <jack@xxxxxxxx>
Honza
> ---
> mm/page-writeback.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++----
> 1 file changed, 46 insertions(+), 4 deletions(-)
>
> diff --git a/mm/page-writeback.c b/mm/page-writeback.c
> index 99b8846..9b55f12 100644
> --- a/mm/page-writeback.c
> +++ b/mm/page-writeback.c
> @@ -155,6 +155,46 @@ static unsigned long writeout_period_time = 0;
> */
> #define VM_COMPLETIONS_PERIOD_LEN (3*HZ)
>
> +#ifdef CONFIG_CGROUP_WRITEBACK
> +
> +static void wb_min_max_ratio(struct bdi_writeback *wb,
> + unsigned long *minp, unsigned long *maxp)
> +{
> + unsigned long this_bw = wb->avg_write_bandwidth;
> + unsigned long tot_bw = atomic_long_read(&wb->bdi->tot_write_bandwidth);
> + unsigned long long min = wb->bdi->min_ratio;
> + unsigned long long max = wb->bdi->max_ratio;
> +
> + /*
> + * @wb may already be clean by the time control reaches here and
> + * the total may not include its bw.
> + */
> + if (this_bw < tot_bw) {
> + if (min) {
> + min *= this_bw;
> + do_div(min, tot_bw);
> + }
> + if (max < 100) {
> + max *= this_bw;
> + do_div(max, tot_bw);
> + }
> + }
> +
> + *minp = min;
> + *maxp = max;
> +}
> +
> +#else /* CONFIG_CGROUP_WRITEBACK */
> +
> +static void wb_min_max_ratio(struct bdi_writeback *wb,
> + unsigned long *minp, unsigned long *maxp)
> +{
> + *minp = wb->bdi->min_ratio;
> + *maxp = wb->bdi->max_ratio;
> +}
> +
> +#endif /* CONFIG_CGROUP_WRITEBACK */
> +
> /*
> * In a memory zone, there is a certain amount of pages we consider
> * available for the page cache, which is essentially the number of
> @@ -539,9 +579,9 @@ static unsigned long hard_dirty_limit(unsigned long thresh)
> */
> unsigned long wb_dirty_limit(struct bdi_writeback *wb, unsigned long dirty)
> {
> - struct backing_dev_info *bdi = wb->bdi;
> u64 wb_dirty;
> long numerator, denominator;
> + unsigned long wb_min_ratio, wb_max_ratio;
>
> /*
> * Calculate this BDI's share of the dirty ratio.
> @@ -552,9 +592,11 @@ unsigned long wb_dirty_limit(struct bdi_writeback *wb, unsigned long dirty)
> wb_dirty *= numerator;
> do_div(wb_dirty, denominator);
>
> - wb_dirty += (dirty * bdi->min_ratio) / 100;
> - if (wb_dirty > (dirty * bdi->max_ratio) / 100)
> - wb_dirty = dirty * bdi->max_ratio / 100;
> + wb_min_max_ratio(wb, &wb_min_ratio, &wb_max_ratio);
> +
> + wb_dirty += (dirty * wb_min_ratio) / 100;
> + if (wb_dirty > (dirty * wb_max_ratio) / 100)
> + wb_dirty = dirty * wb_max_ratio / 100;
>
> return wb_dirty;
> }
> --
> 2.4.0
>
--
Jan Kara <jack@xxxxxxx>
SUSE Labs, CR
--
To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
