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SubjectRe: [patch 4/5] mm: writeback: throttle __GFP_WRITE on per-zone dirty limits
On Mon 25-07-11 22:19:18, Johannes Weiner wrote:
[...]
> diff --git a/mm/page-writeback.c b/mm/page-writeback.c
> index 41dc871..ce673ec 100644
> --- a/mm/page-writeback.c
> +++ b/mm/page-writeback.c
> @@ -378,6 +390,24 @@ int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned max_ratio)
> }
> EXPORT_SYMBOL(bdi_set_max_ratio);
>
> +static void sanitize_dirty_limits(unsigned long *pbackground,
> + unsigned long *pdirty)
> +{
> + unsigned long background = *pbackground;
> + unsigned long dirty = *pdirty;
> + struct task_struct *tsk;
> +
> + if (background >= dirty)
> + background = dirty / 2;
> + tsk = current;
> + if (tsk->flags & PF_LESS_THROTTLE || rt_task(tsk)) {
> + background += background / 4;
> + dirty += dirty / 4;
> + }
> + *pbackground = background;
> + *pdirty = dirty;
> +}
> +
> /*
> * global_dirty_limits - background-writeback and dirty-throttling thresholds
> *
> @@ -389,33 +419,52 @@ EXPORT_SYMBOL(bdi_set_max_ratio);
> */
> void global_dirty_limits(unsigned long *pbackground, unsigned long *pdirty)
> {
> - unsigned long background;
> - unsigned long dirty;
> unsigned long uninitialized_var(available_memory);
> - struct task_struct *tsk;
>
> if (!vm_dirty_bytes || !dirty_background_bytes)
> available_memory = determine_dirtyable_memory();
>
> if (vm_dirty_bytes)
> - dirty = DIV_ROUND_UP(vm_dirty_bytes, PAGE_SIZE);
> + *pdirty = DIV_ROUND_UP(vm_dirty_bytes, PAGE_SIZE);
> else
> - dirty = (vm_dirty_ratio * available_memory) / 100;
> + *pdirty = vm_dirty_ratio * available_memory / 100;
>
> if (dirty_background_bytes)
> - background = DIV_ROUND_UP(dirty_background_bytes, PAGE_SIZE);
> + *pbackground = DIV_ROUND_UP(dirty_background_bytes, PAGE_SIZE);
> else
> - background = (dirty_background_ratio * available_memory) / 100;
> + *pbackground = dirty_background_ratio * available_memory / 100;
>
> - if (background >= dirty)
> - background = dirty / 2;
> - tsk = current;
> - if (tsk->flags & PF_LESS_THROTTLE || rt_task(tsk)) {
> - background += background / 4;
> - dirty += dirty / 4;
> - }
> - *pbackground = background;
> - *pdirty = dirty;
> + sanitize_dirty_limits(pbackground, pdirty);
> +}

Hmm, wouldn't be the patch little bit easier to read if this was
outside in a separate (cleanup) one?

--
Michal Hocko
SUSE Labs
SUSE LINUX s.r.o.
Lihovarska 1060/12
190 00 Praha 9
Czech Republic


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