linux-kernel - Re: [RFC][PATCH] enable VMSPLIT for highmem kernels

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Message-Id: <1154552277.7232.37.camel@localhost.localdomain>
Date:	Wed, 02 Aug 2006 13:57:56 -0700
From:	Dave Hansen <haveblue@...ibm.com>
To:	linux-mm@...ck.org
Cc:	linux-kernel@...r.kernel.org
Subject: Re: [RFC][PATCH] enable VMSPLIT for highmem kernels

Well, I somehow managed to post that without appending my description.
Here goes:

The current VMSPLIT Kconfig option is disabled whenever highmem
is on.  This is a bit screwy because the people who need to
change VMSPLIT the most tend to be the ones with highmem and
constrained lowmem.

So, remove the highmem dependency.  But, re-include the
dependency for the "full 1GB of lowmem" option.  You can't have
the full 1GB of lowmem and highmem because of the need for the
vmalloc(), kmap(), etc... areas.

I thought there would be at least a bit of tweaking to do to
get it to work, but everything seems OK.

Boot tested on a 4GB x86 machine, and a 12GB 3-node NUMA-Q:

elm3b82:~# cat /proc/meminfo
MemTotal:      3695412 kB
MemFree:       3659540 kB
...
LowTotal:      2909008 kB
LowFree:       2892324 kB
...
elm3b82:~# zgrep PAE /proc/config.gz
CONFIG_X86_PAE=y

larry:~# cat /proc/meminfo
MemTotal:     11845900 kB
MemFree:      11786748 kB
...
LowTotal:      2855180 kB
LowFree:       2830092 kB

Signed-off-by: Dave Hansen <haveblue@...ibm.com>

-- Dave

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