From a15fc86c290f33681220d5faf8c8c0c7ca26c309 Mon Sep 17 00:00:00 2001 From: Tetsuro Nakamura Date: Wed, 20 Dec 2017 19:53:57 +0900 Subject: [PATCH] doc: update supported drivers for cpu topology Not only libvirt/KVM driver but also libvirt/QEMU works with cpu topology feature in nova. So we just update the document. Change-Id: If8f0229072c8518c9301a872b98862687d93a044 --- doc/source/admin/cpu-topologies.rst | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/doc/source/admin/cpu-topologies.rst b/doc/source/admin/cpu-topologies.rst index 51d30186a564..12c035796559 100644 --- a/doc/source/admin/cpu-topologies.rst +++ b/doc/source/admin/cpu-topologies.rst @@ -276,6 +276,14 @@ Customizing instance CPU topologies The functionality described below is currently only supported by the libvirt/KVM driver. +.. note:: + Currently it also works with libvirt/QEMU driver but we don't recommend + it in production use cases. This is because vCPUs are actually running + in one thread on host in qemu TCG (Tiny Code Generator), which is the + backend for libvirt/QEMU driver. Work to enable full multi-threading + support for TCG (a.k.a. MTTCG) is on going in QEMU community. Please see + this `MTTCG project`_ page for detail. + In addition to configuring how an instance is scheduled on host CPUs, it is possible to configure how CPUs are represented in the instance itself. By default, when instance NUMA placement is not specified, a topology of N @@ -362,3 +370,4 @@ guide. .. Links .. _`Image metadata`: https://docs.openstack.org/image-guide/image-metadata.html .. _`discussion`: http://lists.openstack.org/pipermail/openstack-dev/2016-March/090367.html +.. _`MTTCG project`: http://wiki.qemu.org/Features/tcg-multithread