From: Andi Kleen <ak@suse.de>
To: "Tony Luck" <tony.luck@intel.com>
Subject: Re: [Patch] Move swiotlb_init early on X86_64
Date: Thu, 2 Mar 2006 05:30:08 +0100
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Cc: "Zou Nan hai" <nanhai.zou@intel.com>, LKML <linux-kernel@vger.kernel.org>,
       "Andrew Morton" <akpm@osdl.org>,
       "Venkatesh Pallipadi" <venkatesh.pallipadi@intel.com>
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On Thursday 02 March 2006 05:15, Tony Luck wrote:
> On 01 Mar 2006 09:10:58 +0800, Zou Nan hai <nanhai.zou@intel.com> wrote:
> > on X86_64, swiotlb buffer is allocated in mem_init, after memmap and vfs cache allocation.
> >
> > On platforms with huge physical memory,
> > large memmap and vfs cache may eat up all usable system memory
> > under 4G.
> >
> > Move swiotlb_init early before memmap is allocated can
> > solve this issue.
> 
> Shouldn't memmap be allocated from memory above 4G (if available)? Using
> up lots of <4G memory on something that doesn't need to be below 4G
> sounds like a poor use of resources.

On the really large machines it will be distributed over the nodes anyways.
But yes the single node SMP case should probably allocate it higher.

-Andi
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