Re: [patch 3/5] mm: try to distribute dirty pages fairly acrosszones

From: KAMEZAWA Hiroyuki
Date: Thu Nov 24 2011 - 20:01:48 EST


On Thu, 24 Nov 2011 14:11:55 +0100
Johannes Weiner <hannes@xxxxxxxxxxx> wrote:

> On Thu, Nov 24, 2011 at 10:07:55AM +0900, KAMEZAWA Hiroyuki wrote:
goto this_zone_full;
> > >
> > > BUILD_BUG_ON(ALLOC_NO_WATERMARKS < NR_WMARK);
> > > if (!(alloc_flags & ALLOC_NO_WATERMARKS)) {
> >
> > This wil call
> >
> > if (NUMA_BUILD)
> > zlc_mark_zone_full(zonelist, z);
> >
> > And this zone will be marked as full.
> >
> > IIUC, zlc_clear_zones_full() is called only when direct reclaim ends.
> > So, if no one calls direct-reclaim, 'full' mark may never be cleared
> > even when number of dirty pages goes down to safe level ?
> > I'm sorry if this is alread discussed.
>
> It does not remember which zones are marked full for longer than a
> second - see zlc_setup() - and also ignores this information when an
> iteration over the zonelist with the cache enabled came up
> empty-handed.
>
Ah, thank you for clarification.
I understand how zlc_active/did_zlc_setup/zlc_setup()...complicated ;)

Thanks,
-Kame

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