Re: [PATCH 08/13] writeback: quit throttling when bdi dirty pagesdropped low

[Peter Zijlstra]

On Wed, 2010-11-24 at 20:30 +0800, Wu Fengguang wrote:
> 
> For the 1-dd case, it looks better to lower the break threshold to
> 125ms. After all, it's not easy for the dirty pages to drop by 250ms
> worth of data when you only slept 200ms (note: the max pause time has
> been doubled mainly for servers).
> 
> -               if (nr_dirty < dirty_thresh &&
> -                   bdi_prev_dirty - bdi_dirty > (long)bdi->write_bandwidth / 4)
> +               if (nr_dirty <= dirty_thresh &&
> +                   bdi_prev_dirty - bdi_dirty > (long)bdi->write_bandwidth / 8)
>                         break;

Hrm, but 125ms worth in 200ms is rather easy, you'd want to keep that
limit above what the pause should give you, right?

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