Re: [PATCH 55/63] sched: numa: Avoid migrating tasks that are placedon their preferred node

[Rik van Riel]

On 10/07/2013 06:29 AM, Mel Gorman wrote:
> From: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> 
> This patch classifies scheduler domains and runqueues into types depending
> the number of tasks that are about their NUMA placement and the number
> that are currently running on their preferred node. The types are
> 
> regular: There are tasks running that do not care about their NUMA
> 	placement.
> 
> remote: There are tasks running that care about their placement but are
> 	currently running on a node remote to their ideal placement
> 
> all: No distinction
> 
> To implement this the patch tracks the number of tasks that are optimally
> NUMA placed (rq->nr_preferred_running) and the number of tasks running
> that care about their placement (nr_numa_running). The load balancer
> uses this information to avoid migrating idea placed NUMA tasks as long
> as better options for load balancing exists. For example, it will not
> consider balancing between a group whose tasks are all perfectly placed
> and a group with remote tasks.
> 
> 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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