From: Christoph Lameter <clameter@sgi.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org
Subject: Re: Use ZVC counters to establish exact size of dirtyable pages
Date: Wed, 14 Feb 2007 14:41:57 -0800 (PST) [thread overview]
Message-ID: <Pine.LNX.4.64.0702141433190.3228@schroedinger.engr.sgi.com> (raw)
In-Reply-To: <20070214142432.a7e913fa.akpm@linux-foundation.org>
On Wed, 14 Feb 2007, Andrew Morton wrote:
> Suppose a zone has ten dirty pages. All the remaining pages in the zone
> are off being used for soundcard buffers and networking skbs.
Thats a pretty artificial situation.There is a min_free_kbytes that
should give us some safety there. Only GFP_ATOMIC could get us there.
> This function will return zero. Which I think we'll happen to handle OK.
One would expect the function to return 10. The 10 pages are on the LRU.
If we really have zero dirtyable pages then we will get a division by
zero problem.
> But this function can, I think, also return negative (ie: very large)
> numbers. I don't think we handle that right.
How would that occur? The only way that I could think this would happen is
if for some strange reason the highmem counts are bigger than the total
counts.
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next prev parent reply other threads:[~2007-02-14 22:41 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-02-12 18:16 Use ZVC counters to establish exact size of dirtyable pages Christoph Lameter
2007-02-13 8:04 ` Andrew Morton
2007-02-13 17:43 ` Christoph Lameter
2007-02-13 18:03 ` Andrew Morton
2007-02-14 22:24 ` Andrew Morton
2007-02-14 22:41 ` Christoph Lameter [this message]
2007-02-14 22:49 ` Christoph Lameter
2007-02-14 23:19 ` Andrew Morton
2007-02-14 23:35 ` Christoph Lameter
2007-02-14 23:44 ` Andrew Morton
2007-02-15 0:00 ` Christoph Lameter
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