Re: Numa Config Effekt in 19c?

From: Mladen Gogala <gogala.mladen_at_gmail.com>
Date: Fri, 24 Jun 2022 13:39:50 -0400
Message-ID: <beb3bb22-3e34-bd20-3da4-2ad910493168_at_gmail.com>

If you have a modern 2-socket server (where remote memory access latency is not multiple times higher than local), keep NUMA awareness off at OS and Oracle level). But, yeah with some (old?) 8 socket server, the multi-hop remote access latency might be so slow that you need either NUMA placement or try to constrain your entire workload (memory and processes) into a single NUMA node, or 2-3 NUMA nodes that have the lowest latency between each other. You might find out that most of your current CPU "usage" is actually stalled CPU empty cycles, waiting for remote memory access...

What should be done with large NUMA machines, like HPE SuperDome Flex or modern IBM large Power 10 servers, which are all NUMA? Those machines are expensive because they need global directory, which is implemented as fully associative RAM. Fully associative RAM is rather expensive. There are many nodes and you need a "phone book" to figure out which node houses your desired memory page. Those large NUMA boxes are direct competitors to RAC.

Regards

-- 
Mladen Gogala
Database Consultant
Tel: (347) 321-1217
https://dbwhisperer.wordpress.com

-- http://www.freelists.org/webpage/oracle-l Received on Fri Jun 24 2022 - 19:39:50 CEST