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

[Igor Mammedov <imammedo@redhat.com>]

On Mon, 8 Jun 2020 08:55:08 -0400
"Michael S. Tsirkin" <mst@redhat.com> wrote:

> On Mon, Jun 08, 2020 at 08:03:44AM -0400, 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@redhat.com>
> > Reviewed-by: Michal Privoznik <mprivozn@redhat.com>  
> 
> Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
> 
Thanks!

> numa things so I'm guessing Eduardo's tree?
yep, it's pure NUMA so it should go via Eduardo's tere.


> > ---
> > v1:
> >  - rebased on top of current master
> >  - move compat mode from 4.2 to 5.0
> > v2:
> >  - move deprection text to recently removed section
> > v3:
> >  - increase title line length for (deprecated.rst)
> >      '``-numa node,mem=``\ *size* (removed in 5.1)'
> > v4:
> >  - use error_append_hint() for suggesting valid CLI
> > 
> > CC: peter.maydell@linaro.org
> > CC: ehabkost@redhat.com
> > CC: marcel.apfelbaum@gmail.com
> > CC: mst@redhat.com
> > CC: pbonzini@redhat.com
> > CC: rth@twiddle.net
> > CC: david@gibson.dropbear.id.au
> > CC: libvir-list@redhat.com
> > CC: qemu-arm@nongnu.org
> > CC: qemu-ppc@nongnu.org
> > CC: eblake@redhat.com
> > CC: groug@kaod.org
> > ---
> >  docs/system/deprecated.rst | 37 ++++++++++++++++++++-----------------
> >  hw/arm/virt.c              |  2 +-
> >  hw/core/numa.c             |  7 +++++++
> >  hw/i386/pc.c               |  1 -
> >  hw/i386/pc_piix.c          |  1 +
> >  hw/i386/pc_q35.c           |  1 +
> >  hw/ppc/spapr.c             |  2 +-
> >  qemu-options.hx            |  9 +++++----
> >  8 files changed, 36 insertions(+), 24 deletions(-)
> > 
> > diff --git a/docs/system/deprecated.rst b/docs/system/deprecated.rst
> > index 544ece0a45..e74a5717c8 100644
> > --- a/docs/system/deprecated.rst
> > +++ 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  The ``-realtime mlock=on|off`` argument has been replaced by the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
> > -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
> > +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.
> > diff --git a/hw/arm/virt.c b/hw/arm/virt.c
> > index 37462a6f78..063d4703f7 100644
> > --- a/hw/arm/virt.c
> > +++ b/hw/arm/virt.c
> > @@ -2262,7 +2262,6 @@ static void virt_machine_class_init(ObjectClass *oc, void *data)
> >      hc->pre_plug = virt_machine_device_pre_plug_cb;
> >      hc->plug = virt_machine_device_plug_cb;
> >      hc->unplug_request = virt_machine_device_unplug_request_cb;
> > -    mc->numa_mem_supported = true;
> >      mc->nvdimm_supported = true;
> >      mc->auto_enable_numa_with_memhp = true;
> >      mc->default_ram_id = "mach-virt.ram";
> > @@ -2375,6 +2374,7 @@ DEFINE_VIRT_MACHINE_AS_LATEST(5, 1)
> >  static void virt_machine_5_0_options(MachineClass *mc)
> >  {
> >      virt_machine_5_1_options(mc);
> > +    mc->numa_mem_supported = true;
> >  }
> >  DEFINE_VIRT_MACHINE(5, 0)
> >  
> > diff --git a/hw/core/numa.c b/hw/core/numa.c
> > index 316bc50d75..7814e646e4 100644
> > --- a/hw/core/numa.c
> > +++ b/hw/core/numa.c
> > @@ -117,6 +117,13 @@ static void parse_numa_node(MachineState *ms, NumaNodeOptions *node,
> >      }
> >  
> >      if (node->has_mem) {
> > +        if (!mc->numa_mem_supported) {
> > +            error_setg(errp, "Parameter -numa node,mem is not supported by this"
> > +                      " machine type");
> > +            error_append_hint(errp, "Use -numa node,memdev instead");
> > +            return;
> > +        }
> > +
> >          numa_info[nodenr].node_mem = node->mem;
> >          if (!qtest_enabled()) {
> >              warn_report("Parameter -numa node,mem is deprecated,"
> > diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> > index 2128f3d6fe..a86136069c 100644
> > --- a/hw/i386/pc.c
> > +++ b/hw/i386/pc.c
> > @@ -1960,7 +1960,6 @@ static void pc_machine_class_init(ObjectClass *oc, void *data)
> >      hc->unplug = pc_machine_device_unplug_cb;
> >      mc->default_cpu_type = TARGET_DEFAULT_CPU_TYPE;
> >      mc->nvdimm_supported = true;
> > -    mc->numa_mem_supported = true;
> >      mc->default_ram_id = "pc.ram";
> >  
> >      object_class_property_add(oc, PC_MACHINE_DEVMEM_REGION_SIZE, "int",
> > diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
> > index f66e1d73ce..8955436efa 100644
> > --- a/hw/i386/pc_piix.c
> > +++ b/hw/i386/pc_piix.c
> > @@ -438,6 +438,7 @@ static void pc_i440fx_5_0_machine_options(MachineClass *m)
> >      pc_i440fx_5_1_machine_options(m);
> >      m->alias = NULL;
> >      m->is_default = false;
> > +    m->numa_mem_supported = true;
> >      compat_props_add(m->compat_props, hw_compat_5_0, hw_compat_5_0_len);
> >      compat_props_add(m->compat_props, pc_compat_5_0, pc_compat_5_0_len);
> >  }
> > diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
> > index 4ba8ac8774..af6b32adb7 100644
> > --- a/hw/i386/pc_q35.c
> > +++ b/hw/i386/pc_q35.c
> > @@ -366,6 +366,7 @@ static void pc_q35_5_0_machine_options(MachineClass *m)
> >  {
> >      pc_q35_5_1_machine_options(m);
> >      m->alias = NULL;
> > +    m->numa_mem_supported = true;
> >      compat_props_add(m->compat_props, hw_compat_5_0, hw_compat_5_0_len);
> >      compat_props_add(m->compat_props, pc_compat_5_0, pc_compat_5_0_len);
> >  }
> > diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> > index 3b1a5ed865..210d61d1b3 100644
> > --- a/hw/ppc/spapr.c
> > +++ b/hw/ppc/spapr.c
> > @@ -4511,7 +4511,6 @@ static void spapr_machine_class_init(ObjectClass *oc, void *data)
> >       * in which LMBs are represented and hot-added
> >       */
> >      mc->numa_mem_align_shift = 28;
> > -    mc->numa_mem_supported = true;
> >      mc->auto_enable_numa = true;
> >  
> >      smc->default_caps.caps[SPAPR_CAP_HTM] = SPAPR_CAP_OFF;
> > @@ -4599,6 +4598,7 @@ static void spapr_machine_5_0_class_options(MachineClass *mc)
> >  {
> >      spapr_machine_5_1_class_options(mc);
> >      compat_props_add(mc->compat_props, hw_compat_5_0, hw_compat_5_0_len);
> > +    mc->numa_mem_supported = true;
> >  }
> >  
> >  DEFINE_SPAPR_MACHINE(5_0, "5.0", false);
> > diff --git a/qemu-options.hx b/qemu-options.hx
> > index 93bde2bbc8..196f468786 100644
> > --- a/qemu-options.hx
> > +++ b/qemu-options.hx
> > @@ -239,10 +239,11 @@ SRST
> >          -numa node,nodeid=0 -numa node,nodeid=1 \
> >          -numa cpu,node-id=0,socket-id=0 -numa cpu,node-id=1,socket-id=1
> >  
> > -    '\ ``mem``\ ' assigns a given RAM amount to a node. '\ ``memdev``\ '
> > -    assigns RAM from a given memory backend device to a node. If
> > -    '\ ``mem``\ ' and '\ ``memdev``\ ' are omitted in all nodes, RAM is
> > -    split equally between them.
> > +    Legacy '\ ``mem``\ ' assigns a given RAM amount to a node (not supported
> > +    for 5.1 and newer machine types). '\ ``memdev``\ ' assigns RAM from
> > +    a given memory backend device to a node. If '\ ``mem``\ ' and
> > +    '\ ``memdev``\ ' are omitted in all nodes, RAM is split equally between them.
> > +
> >  
> >      '\ ``mem``\ ' and '\ ``memdev``\ ' are mutually exclusive.
> >      Furthermore, if one node uses '\ ``memdev``\ ', all of them have to
> > -- 
> > 2.26.2  
>