diff mbox series

[v2] docs/system/cpu-hotplug: Update example's socket-id/core-id

Message ID 20241010131800.3210161-1-peter.maydell@linaro.org (mailing list archive)
State New, archived
Headers show
Series [v2] docs/system/cpu-hotplug: Update example's socket-id/core-id | expand

Commit Message

Peter Maydell Oct. 10, 2024, 1:18 p.m. UTC 
The example of how to do vCPU hotplug and hot-unlpug in the
cpu-hotplug documentation no longer works, because the way we
allocate socket-id and core-id to CPUs by default has changed at some
point.  The output also no longer matches what current QEMU produces
in some more cosmetic ways.

Update the example to match current QEMU. The differences are:
 * the second CPU is now socket-id=0 core-id=1,
   not socket-id=1 core-id=0
 * the order of fields in QMP responses is now in alphabetical order
 * the "arch" member is no longer present in the query-cpus-fast
   output (it was removed in QEMU 6.0)

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Acked-by: Igor Mammedov <imammedo@redhat.com>
Message-id: 20240819144303.37852-1-peter.maydell@linaro.org
---
v1->v2:
 * update device_add command line to use right socket-id/core-id
 * expand commit message to mention that "arch" field has gone
---
 docs/system/cpu-hotplug.rst | 56 ++++++++++++++++++-------------------
 1 file changed, 27 insertions(+), 29 deletions(-)

Comments

Peter Maydell Oct. 18, 2024, 3:52 p.m. UTC | #1 
On Thu, 10 Oct 2024 at 14:18, Peter Maydell <peter.maydell@linaro.org> wrote:
>
> The example of how to do vCPU hotplug and hot-unlpug in the
> cpu-hotplug documentation no longer works, because the way we
> allocate socket-id and core-id to CPUs by default has changed at some
> point.  The output also no longer matches what current QEMU produces
> in some more cosmetic ways.
>
> Update the example to match current QEMU. The differences are:
>  * the second CPU is now socket-id=0 core-id=1,
>    not socket-id=1 core-id=0
>  * the order of fields in QMP responses is now in alphabetical order
>  * the "arch" member is no longer present in the query-cpus-fast
>    output (it was removed in QEMU 6.0)
>
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> Acked-by: Igor Mammedov <imammedo@redhat.com>
> Message-id: 20240819144303.37852-1-peter.maydell@linaro.org


I'll take this via target-arm.next unless there are any
objections.

thanks
-- PMM
diff mbox series

Patch

diff --git a/docs/system/cpu-hotplug.rst b/docs/system/cpu-hotplug.rst
index 015ce2b6ec3..cc50937c36c 100644
--- a/docs/system/cpu-hotplug.rst
+++ b/docs/system/cpu-hotplug.rst
@@ -33,23 +33,23 @@  vCPU hotplug
       {
           "return": [
               {
-                  "type": "IvyBridge-IBRS-x86_64-cpu",
-                  "vcpus-count": 1,
                   "props": {
-                      "socket-id": 1,
-                      "core-id": 0,
+                      "core-id": 1,
+                      "socket-id": 0,
                       "thread-id": 0
-                  }
+                  },
+                  "type": "IvyBridge-IBRS-x86_64-cpu",
+                  "vcpus-count": 1
               },
               {
+                  "props": {
+                      "core-id": 0,
+                      "socket-id": 0,
+                      "thread-id": 0
+                  },
                   "qom-path": "/machine/unattached/device[0]",
                   "type": "IvyBridge-IBRS-x86_64-cpu",
-                  "vcpus-count": 1,
-                  "props": {
-                      "socket-id": 0,
-                      "core-id": 0,
-                      "thread-id": 0
-                  }
+                  "vcpus-count": 1
               }
           ]
       }
@@ -58,18 +58,18 @@  vCPU hotplug
 (4) The ``query-hotpluggable-cpus`` command returns an object for CPUs
     that are present (containing a "qom-path" member) or which may be
     hot-plugged (no "qom-path" member).  From its output in step (3), we
-    can see that ``IvyBridge-IBRS-x86_64-cpu`` is present in socket 0,
-    while hot-plugging a CPU into socket 1 requires passing the listed
+    can see that ``IvyBridge-IBRS-x86_64-cpu`` is present in socket 0 core 0,
+    while hot-plugging a CPU into socket 0 core 1 requires passing the listed
     properties to QMP ``device_add``::
 
-      (QEMU) device_add id=cpu-2 driver=IvyBridge-IBRS-x86_64-cpu socket-id=1 core-id=0 thread-id=0
+      (QEMU) device_add id=cpu-2 driver=IvyBridge-IBRS-x86_64-cpu socket-id=0 core-id=1 thread-id=0
       {
           "execute": "device_add",
           "arguments": {
-              "socket-id": 1,
+              "core-id": 1,
               "driver": "IvyBridge-IBRS-x86_64-cpu",
               "id": "cpu-2",
-              "core-id": 0,
+              "socket-id": 0,
               "thread-id": 0
           }
       }
@@ -83,34 +83,32 @@  vCPU hotplug
 
       (QEMU) query-cpus-fast
       {
-          "execute": "query-cpus-fast",
           "arguments": {}
+          "execute": "query-cpus-fast",
       }
       {
           "return": [
               {
-                  "qom-path": "/machine/unattached/device[0]",
-                  "target": "x86_64",
-                  "thread-id": 11534,
                   "cpu-index": 0,
                   "props": {
-                      "socket-id": 0,
                       "core-id": 0,
+                      "socket-id": 0,
                       "thread-id": 0
                   },
-                  "arch": "x86"
+                  "qom-path": "/machine/unattached/device[0]",
+                  "target": "x86_64",
+                  "thread-id": 28957
               },
               {
-                  "qom-path": "/machine/peripheral/cpu-2",
-                  "target": "x86_64",
-                  "thread-id": 12106,
                   "cpu-index": 1,
                   "props": {
-                      "socket-id": 1,
-                      "core-id": 0,
+                      "core-id": 1,
+                      "socket-id": 0,
                       "thread-id": 0
                   },
-                  "arch": "x86"
+                  "qom-path": "/machine/peripheral/cpu-2",
+                  "target": "x86_64",
+                  "thread-id": 29095
               }
           ]
       }
@@ -123,10 +121,10 @@  From the 'qmp-shell', invoke the QMP ``device_del`` command::
 
       (QEMU) device_del id=cpu-2
       {
-          "execute": "device_del",
           "arguments": {
               "id": "cpu-2"
           }
+          "execute": "device_del",
       }
       {
           "return": {}