[Qemu-devel] [PATCH 0/3] cpu: numa: Fix the mapping initialization of VCPUs and NUMA nodes

[Dou Liyang]

As we fixed a bug(Bug 1) in below links, Named "Method-A":

https://lists.nongnu.org/archive/html/qemu-devel/2017-01/msg03354.html

Then, Eduardo gave us many suggests. Thanks very much!
when we try them, we also find another bugs named "Bug 2".

[Problem]
---------

As I use this command:

./x86_64-softmmu/qemu-system-x86_64 \
        -hda /image/fedora.img \
        -m 1G,slots=4,maxmem=4G \
        -enable-kvm \
        -smp 2,maxcpus=16,sockets=4,cores=2,threads=2 \
        -device qemu64-x86_64-cpu,id=cpu1,socket-id=0,core-id=1,thread-id=0 \
        -device qemu64-x86_64-cpu,id=cpu2,socket-id=0,core-id=1,thread-id=1 \
        -device qemu64-x86_64-cpu,id=cpu3,socket-id=1,core-id=0,thread-id=0 \
        -device qemu64-x86_64-cpu,id=cpu4,socket-id=1,core-id=0,thread-id=1 \
        -device qemu64-x86_64-cpu,id=cpu5,socket-id=1,core-id=1,thread-id=0 \
        -device qemu64-x86_64-cpu,id=cpu6,socket-id=1,core-id=1,thread-id=1 \
        -numa node,nodeid=0,cpus=0-3 \
        -numa node,nodeid=1,cpus=4-7 \
        -numa node,nodeid=2,cpus=8-11 \
        -numa node,nodeid=3,cpus=12-15 \
        -monitor stdio \

1. Bug 1
--------
In Qemu monitor:

(qemu) info numa 
4 nodes
node 0 cpus: 0 1 2 3 4 5 6 7
node 0 size: 256 MB
node 1 cpus:
node 1 size: 256 MB
node 2 cpus:
node 2 size: 256 MB
node 3 cpus:
node 3 size: 256 MB

2. Bug 2
--------
(qemu) device_add qemu64-x86_64-cpu,id=cpu7,socket-id=2,core-id=0,thread-id=0

(qemu) info numa
4 nodes
node 0 cpus: 0 1 2 3 4 5 6 7 8
node 0 size: 256 MB
node 1 cpus:
node 1 size: 256 MB
node 2 cpus:
node 2 size: 256 MB
node 3 cpus:
node 3 size: 256 MB

[Method-A]
----------

1. Method-A that we provided above: 
  * Ensure the numa_post_machine_init func in the appropriate location in
vl.c::main().

It can fix Bug 1, but, can't work for Bug 2.

1.1. For Bug 1: fixed

(qemu) info numa
4 nodes
node 0 cpus: 0 1 2 3
node 0 size: 256 MB
node 1 cpus: 4 5 6 7
node 1 size: 256 MB
node 2 cpus:
node 2 size: 256 MB
node 3 cpus:
node 3 size: 256 MB

1.2. For Bug 2: can not fixed

(qemu) device_add qemu64-x86_64-cpu,id=cpu7,socket-id=2,core-id=0,thread-id=0

(qemu) info numa
node 0 cpus: 0 1 2 3 8
node 0 size: 256 MB
node 1 cpus: 4 5 6 7
node 1 size: 256 MB
node 2 cpus:
node 2 size: 256 MB
node 3 cpus:
node 3 size: 256 MB

[Solution]
----------

Move the CPUState::numa_node initialization to qom/cpu.c:cpu_common_realizefn(),
and remove numa_post_machine_init() completely.

It can fix Bug 1 and Bug 2. The result shows that:

(qemu) info numa
4 nodes
node 0 cpus: 0 1 2 3
node 0 size: 256 MB
node 1 cpus: 4 5 6 7
node 1 size: 256 MB
node 2 cpus:
node 2 size: 256 MB
node 3 cpus:
node 3 size: 256 MB

(qemu) device_add qemu64-x86_64-cpu,id=cpu7,socket-id=2,core-id=0,thread-id=0
(qemu) info numa
4 nodes
node 0 cpus: 0 1 2 3
node 0 size: 256 MB
node 1 cpus: 4 5 6 7
node 1 size: 256 MB
node 2 cpus: 8
node 2 size: 256 MB
node 3 cpus:
node 3 size: 256 MB

(qemu) device_add qemu64-x86_64-cpu,id=cpu8,socket-id=3,core-id=0,thread-id=0
(qemu) info numa
4 nodes
node 0 cpus: 0 1 2 3
node 0 size: 256 MB
node 1 cpus: 4 5 6 7
node 1 size: 256 MB
node 2 cpus: 8
node 2 size: 256 MB
node 3 cpus: 12
node 3 size: 256 MB

(qemu) device_del cpu5
(qemu) info numa
4 nodes
node 0 cpus: 0 1 2 3
node 0 size: 256 MB
node 1 cpus: 4 5 7
node 1 size: 256 MB
node 2 cpus: 8
node 2 size: 256 MB
node 3 cpus: 12
node 3 size: 256 MB

Dou Liyang (3):
  cpu: Make the mapping of CPUs and NUMA nodes in cpu_common_realizefn
  numa: Remove the numa_post_machine_init function
  cpu: make the function of cpu_common_map_numa_node more efficiently

 include/sysemu/numa.h |  1 -
 numa.c                | 15 ---------------
 qom/cpu.c             | 16 ++++++++++++++++
 vl.c                  |  2 --
 4 files changed, 16 insertions(+), 18 deletions(-)

-- 
2.5.5