From: Roger Larsson <roger.larsson@norran.net>
To: Rik van Riel <riel@conectiva.com.br>
Cc: linux-mm@kvack.org
Subject: Re: [PATCH] __alloc_pages_limit pages_min
Date: Wed, 22 Aug 2001 22:58:59 +0200 [thread overview]
Message-ID: <200108222103.f7ML3Lb26463@maile.telia.com> (raw)
In-Reply-To: <Pine.LNX.4.33L.0108221400290.31410-100000@duckman.distro.conectiva>
On Wednesdayen den 22 August 2001 19:01, Rik van Riel wrote:
> On Wed, 22 Aug 2001, Roger Larsson wrote:
> > Note: reclaim_page will fix this situation direct it is allowed to
> > run since it is kicked in __alloc_pages. But since we cannot
> > guarantee that this will never happen...
>
> In this case kreclaimd will be woken up and the free pages
> will be refilled.
>
> Rik
Yes it will be woken up - but when will it actually do something?
(we might have lots of stuff before in the run queue)
Suppose we are at low for all zones on free pages - the natural.
And we get requsts for DMA pages, non direct_reclaim.
(with inactive_clean greater than pages_high)
An alloc will then take let you allocate at the first __alloc_pages_limit
until zero pages left. You might have got it anyway but not until a
later test in __alloc_pages but it is not guaranteed.
We should not accept to let free_pages go (more than one) under
pages_min, at least not as a undocumented feature of __alloc_pages_limit...
It might be worse then first tought of since all allocations with order != 0
are non direct_reclaim... you might eat the free pages fast...
And this limit at the end of alloc_pages
if (z->free_pages < z->pages_min / 4 &&
!(current->flags & PF_MEMALLOC))
is not enforced earlier in the same code...
/RogerL
--
Roger Larsson
Skelleftea
Sweden
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next prev parent reply other threads:[~2001-08-22 20:58 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-08-22 15:12 Roger Larsson
2001-08-22 17:01 ` Rik van Riel
2001-08-22 20:58 ` Roger Larsson [this message]
2001-08-22 21:10 ` Rik van Riel
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