From 82b9a39ed8cfc9944d47ca51ff230e8ab6666a17 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Edwin=20T=C3=B6r=C3=B6k?= Date: Thu, 2 Nov 2023 18:50:19 +0000 Subject: [PATCH] CP-38020: enable best effort NUMA affinity placement by default MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit For some workloads this is an improvement: it places VMs on a small number of NUMA node, so each VM will perform local memory accesses where possible, which has lower latency. There are some workloads where this is a regression: now a VM can only use the bandwidth of a single NUMA node, rather than all NUMA nodes. However this advantage is only present while the VM is the only one using the system, if there are multiple VMs then fairly soon they will all do remote memory accesses, overloading the QPI links. The user can still override this on a host by host basis if their workloads require the previous behaviour. TODO: some actual benchmarks to support this theory Signed-off-by: Edwin Török --- ocaml/xapi/xapi_xenops.ml | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/ocaml/xapi/xapi_xenops.ml b/ocaml/xapi/xapi_xenops.ml index ac92853d104..2d5635c68f9 100644 --- a/ocaml/xapi/xapi_xenops.ml +++ b/ocaml/xapi/xapi_xenops.ml @@ -3146,7 +3146,7 @@ let set_numa_affinity_policy ~__context ~value = | `best_effort -> Best_effort | `default_policy -> - Any + Best_effort in Client.HOST.set_numa_affinity_policy dbg value