Re: [PATCH 03/13] writeback: add comment to the dirty limits functions

Peter Zijlstra
2010-08-06T10:17:26Z

On Fri, 2010-08-06 at 00:10 +0800, Wu Fengguang wrote:

Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>

> +/**
> + * bdi_dirty_limit - @bdi's share of dirty throttling threshold
> + *
> + * Allocate high/low dirty limits to fast/slow devices, in order to prevent
> + * - starving fast devices
> + * - piling up dirty pages (that will take long time to sync) on slow devices
> + *
> + * The bdi's share of dirty limit will be adapting to its throughput and
> + * bounded by the bdi->min_ratio and/or bdi->max_ratio parameters, if set.
> + */

Another thing solved by the introduction of per-bdi dirty limits (and
now per-bdi flushing) is the whole stacked-bdi writeout deadlock.

Although I'm not sure we want/need to mention that here.