Re: [PATCH 0/50] Basic scheduler support for automatic NUMA balancingV7

From: Bob Liu
Date: Fri Sep 13 2013 - 22:58:06 EST


Hi Mel,

On 09/10/2013 05:31 PM, Mel Gorman wrote:
> It has been a long time since V6 of this series and time for an update. Much
> of this is now stabilised with the most important addition being the inclusion
> of Peter and Rik's work on grouping tasks that share pages together.
>
> This series has a number of goals. It reduces overhead of automatic balancing
> through scan rate reduction and the avoidance of TLB flushes. It selects a
> preferred node and moves tasks towards their memory as well as moving memory
> toward their task. It handles shared pages and groups related tasks together.
>

I found sometimes numa balancing will be broken after khugepaged
started, because khugepaged always allocate huge page from the node of
the first scanned normal page during collapsing.

A simple use case is when a user run his application interleaving all
nodes using "numactl --interleave=all xxxx".
But after khugepaged started most pages of his application will be
located to only one specific node.

I have a simple patch fix this issue in thread:
[PATCH 2/2] mm: thp: khugepaged: add policy for finding target node

I think this may related with this topic, I don't know whether this
series can also fix the issue I mentioned.

--
Regards,
-Bob
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