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SubjectRe: [patch 4/5] mm: writeback: throttle __GFP_WRITE on per-zone dirty limits
On Wed 03-08-11 22:25:00, Johannes Weiner wrote:
> On Wed, Jul 27, 2011 at 04:24:05PM +0200, Michal Hocko wrote:
> > 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?
>
> I didn't find it hard to read. But I wrote it, so... :)
>
> Will split it out in the next round. Thanks, Michal.

Thanks

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


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