Re: [PATCH 43/63] sched: numa: Use {cpu, pid} to create task groupsfor shared faults

[Rik van Riel]

On 10/07/2013 06:29 AM, Mel Gorman wrote:
> From: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> 
> While parallel applications tend to align their data on the cache
> boundary, they tend not to align on the page or THP boundary.
> Consequently tasks that partition their data can still "false-share"
> pages presenting a problem for optimal NUMA placement.
> 
> This patch uses NUMA hinting faults to chain tasks together into
> numa_groups. As well as storing the NID a task was running on when
> accessing a page a truncated representation of the faulting PID is
> stored. If subsequent faults are from different PIDs it is reasonable
> to assume that those two tasks share a page and are candidates for
> being grouped together. Note that this patch makes no scheduling
> decisions based on the grouping information.
> 
> Signed-off-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Signed-off-by: Mel Gorman <mgorman@xxxxxxx>

Reviewed-by: Rik van Riel <riel@xxxxxxxxxx>


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