From: Andrew Morton <akpm@osdl.org>
To: Aubrey <aubreylee@gmail.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: page allocation failure when cached memory is close to the total memory.
Date: Wed, 1 Mar 2006 20:01:06 -0800 [thread overview]
Message-ID: <20060301200106.080bd72a.akpm@osdl.org> (raw)
In-Reply-To: <6d6a94c50603011937p61bea6ddl691ee1cdb309d14d@mail.gmail.com>
Aubrey <aubreylee@gmail.com> wrote:
>
> > The chances of finding 10MB of contiguous free pages are basically nil, so
> > the page allocator doesn't even try to free up pages to attempt to satisfy
> > such a large request. If it can't find the 10MB of free memory
> > immediately, it just gives up.
>
> Nope.
Yup.
> I've tested the case on the host. See below. The allocation for
> 300MB was sucessful when the cached memory was close to the total
> memory.
The host has an MMU and hence is able to map discontiguous physical pages
into a virtually contiguous block. The blackfin doesn't have an MMU and
hence requires that 10MB's worth of physically contiguous pages be free.
Which is so hard to achieve after the system has been up for a while that
the kernel won't even attempt it.
next prev parent reply other threads:[~2006-03-02 4:02 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-03-01 9:54 Aubrey
2006-03-01 10:36 ` Andrew Morton
2006-03-02 3:37 ` Aubrey
2006-03-02 4:01 ` Andrew Morton [this message]
2006-03-02 4:03 ` Nick Piggin
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