Re: [PATCH 13/18] mm: numa: Scan pages with elevated page_mapcount

[Mel Gorman]

On Wed, Jul 17, 2013 at 01:22:22PM +0800, Sam Ben wrote:
> On 07/15/2013 11:20 PM, Mel Gorman wrote:
> >Currently automatic NUMA balancing is unable to distinguish between false
> >shared versus private pages except by ignoring pages with an elevated
> 
> What's the meaning of false shared?
> 

Two tasks may be operating on a shared buffer that is not aligned. It is
expected that will at least cache align to avoid CPU cache line bouncing
but the buffers are not necessarily page aligned. A page is the minimum
granularity we can track NUMA hinting faults so two tasks sharing
such a page will appear to be sharing data when in fact they are not.

-- 
Mel Gorman
SUSE Labs
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