Messages in this thread | | | Date | Tue, 8 Apr 2014 09:17:04 -0500 (CDT) | From | Christoph Lameter <> | Subject | Re: [PATCH 0/2] Disable zone_reclaim_mode by default |
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On Tue, 8 Apr 2014, Vlastimil Babka wrote:
> On 04/08/2014 12:34 AM, Mel Gorman wrote: > > When it was introduced, zone_reclaim_mode made sense as NUMA distances > > punished and workloads were generally partitioned to fit into a NUMA > > node. NUMA machines are now common but few of the workloads are NUMA-aware > > and it's routine to see major performance due to zone_reclaim_mode being > > disabled but relatively few can identify the problem. > ^ I think you meant "enabled" here? > > Just in case the cover letter goes to the changelog...
Correct.
Another solution here would be to increase the threshhold so that 4 socket machines do not enable zone reclaim by default. The larger the NUMA system is the more memory is off node from the perspective of a processor and the larger the hit from remote memory.
On the other hand: The more expensive we make reclaim the less it makes sense to allow zone reclaim to occur.
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