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mbrose1994 01-23-2017 01:37 PM

App is moved to different NUMA node, how is shared memory handled?
 
I need to improve the performance of a very large application that is heavily threaded.

My hardware is a HP ProLient, 96 Gig RAM, 8 NUMA nodes, 64 CPUs, 8 per node, RHEL Linux 6.8 x86_64.

The tech materials have no mentioned if shared memory is moved when I move an application from say NUMA node 0 to NUMA node 4. I am using TUNA to do the adjustments of applications.

If anyone has experience and/or insight using TUNA, numactl and other such tools, I would love to learn from your experiences.

syg00 01-24-2017 07:05 PM

When moving a task, the memory will be handled automatically - in time it may all migrate to the new nodes local memory.
Or not. Depending on memory pressure.

A better strategy is to start the application on the preferred node. Then memory will be allocated from that nodes local memory first. Easiest done using cgroups or namespace containers like LXC. Due to inheritance, all child processes will use the same nodes resouces.


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