From: Jesse Barnes <jbarnes@sgi.com>
To: William Lee Irwin III <wli@holomorphy.com>
Subject: Re: Hugepages demand paging V2 [0/8]: Discussion and overview
Date: Mon, 25 Oct 2004 19:40:30 -0700
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Cc: Christoph Lameter <clameter@sgi.com>,
       "Chen, Kenneth W" <kenneth.w.chen@intel.com>,
       linux-kernel@vger.kernel.org
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On Monday, October 25, 2004 7:23 pm, William Lee Irwin III wrote:
> On Mon, Oct 25, 2004 at 06:26:42PM -0700, Christoph Lameter wrote:
> > - Clearing hugetlb pages is time consuming using clear_highpage in
> > alloc_huge_page. Make it possible to use hw assist via DMA or so there?
>
> It's possible, but it's been found not to be useful. What has been found
> useful is assistance from much lower-level memory hardware of a kind
> not to be had in any extant mass-manufactured machines.

Do you have examples?  SGI hardware has a so-called 'BTE' (for Block Transfer 
Engine) that can arbitrarily zero or copy pages w/o CPU assistance.  It's 
builtin to the memory controller.  Using it to zero the pages has the 
advantages of being asyncrhonous and not hosing the CPU cache.

Jesse
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