Re: [PATCH v4] numa: forbid '-numa node,mem' for 5.1 and newer machine types

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On 6/8/20 7:03 AM, Igor Mammedov wrote:
Deprecation period is run out and it's a time to flip the switch
introduced by cd5ff8333a.  Disable legacy option for new machine
types (since 5.1) and amend documentation.

'-numa node,memdev' shall be used instead of disabled option
with new machine types.

Signed-off-by: Igor Mammedov <imammedo@xxxxxxxxxx>
Reviewed-by: Michal Privoznik <mprivozn@xxxxxxxxxx>
---

+++ b/docs/system/deprecated.rst
@@ -101,23 +101,6 @@ error in the future.
  The ``-realtime mlock=on|off`` argument has been replaced by the
  ``-overcommit mem-lock=on|off`` argument.
-``-numa node,mem=``\ *size* (since 4.1)
-'''''''''''''''''''''''''''''''''''''''
-
-The parameter ``mem`` of ``-numa node`` is used to assign a part of

Present tense in the old text made sense because the old way still worked...

-guest RAM to a NUMA node. But when using it, it's impossible to manage specified
-RAM chunk on the host side (like bind it to a host node, setting bind policy, ...),
-so guest end-ups with the fake NUMA configuration with suboptiomal performance.
-However since 2014 there is an alternative way to assign RAM to a NUMA node
-using parameter ``memdev``, which does the same as ``mem`` and adds
-means to actualy manage node RAM on the host side. Use parameter ``memdev``
-with *memory-backend-ram* backend as an replacement for parameter ``mem``
-to achieve the same fake NUMA effect or a properly configured
-*memory-backend-file* backend to actually benefit from NUMA configuration.
-In future new machine versions will not accept the option but it will still
-work with old machine types. User can check QAPI schema to see if the legacy
-option is supported by looking at MachineInfo::numa-mem-supported property.
-
  ``-numa`` node (without memory specified) (since 4.1)
  '''''''''''''''''''''''''''''''''''''''''''''''''''''
@@ -516,3 +499,23 @@ long starting at 1MiB, the old command::
  can be rewritten as::
qemu-nbd -t --image-opts driver=raw,offset=1M,size=100M,file.driver=qcow2,file.file.driver=file,file.file.filename=file.qcow2
+
+Command line options
+--------------------
+
+``-numa node,mem=``\ *size* (removed in 5.1)
+''''''''''''''''''''''''''''''''''''''''''''
+
+The parameter ``mem`` of ``-numa node`` is used to assign a part of

...but in the new text, if we completely got rid of 'mem', then past tense is preferred to describe what used to work. s/is/was/

Other pre-existing typo and grammar problems worth fixing now:

+guest RAM to a NUMA node. But when using it, it's impossible to manage specified

s/manage/manage a/

+RAM chunk on the host side (like bind it to a host node, setting bind policy, ...),
+so guest end-ups with the fake NUMA configuration with suboptiomal performance.

s/so guest end-ups/so the guest ends up/

+However since 2014 there is an alternative way to assign RAM to a NUMA node
+using parameter ``memdev``, which does the same as ``mem`` and adds
+means to actualy manage node RAM on the host side. Use parameter ``memdev``

s/actualy/actually/

+with *memory-backend-ram* backend as an replacement for parameter ``mem``

s/an/a/

+to achieve the same fake NUMA effect or a properly configured
+*memory-backend-file* backend to actually benefit from NUMA configuration.
+In future new machine versions will not accept the option but it will still

If this sentence is still true:
s/In future new/New/

If the sentence is false (that is, we completely dropped 'mem' even for old machine versions), drop it.

+work with old machine types. User can check QAPI schema to see if the legacy

s/check/check the/

+option is supported by looking at MachineInfo::numa-mem-supported property.

--
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org




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