Commit 32a354dc authored by Igor Mammedov's avatar Igor Mammedov Committed by Paolo Bonzini
Browse files

numa: forbid '-numa node, mem' for 5.1 and newer machine types 



Deprecation period is run out and it's a time to flip the switch
introduced by cd5ff833.  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: default avatarIgor Mammedov <imammedo@redhat.com>
Reviewed-by: default avatarMichal Privoznik <mprivozn@redhat.com>
Reviewed-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Reviewed-by: default avatarGreg Kurz <groug@kaod.org>
Message-Id: <20200609135635.761587-1-imammedo@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent f9919116

docs/system/deprecated.rst

+20 −17
Original line number Diff line number Diff line
@@ -95,23 +95,6 @@ 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The ``-realtime mlock=on|off`` argument has been replaced by the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)

'''''''''''''''''''''''''''''''''''''''''''''''''''''
@@ -553,3 +536,23 @@ 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`` was used to assign a part of

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

RAM chunk on the host side (like bind it to a host node, setting bind policy, ...),

so the guest ends up 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 actually manage node RAM on the host side. Use parameter ``memdev``

with *memory-backend-ram* backend as 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.

New machine versions (since 5.1) will not accept the option but it will still

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

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

hw/arm/virt.c

+1 −1
Original line number Diff line number Diff line
@@ -2320,7 +2320,6 @@ static void virt_machine_class_init(ObjectClass *oc, void *data) 
    hc->plug = virt_machine_device_plug_cb;

    hc->unplug_request = virt_machine_device_unplug_request_cb;

    hc->unplug = virt_machine_device_unplug_cb;

    mc->numa_mem_supported = true;

    mc->nvdimm_supported = true;

    mc->auto_enable_numa_with_memhp = true;

    mc->default_ram_id = "mach-virt.ram";
@@ -2434,6 +2433,7 @@ static void virt_machine_5_0_options(MachineClass *mc) 
{

    virt_machine_5_1_options(mc);

    compat_props_add(mc->compat_props, hw_compat_5_0, hw_compat_5_0_len);

    mc->numa_mem_supported = true;

}

DEFINE_VIRT_MACHINE(5, 0)

hw/core/numa.c

+7 −0
Original line number Diff line number Diff line
@@ -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\n");

            return;

        }



        numa_info[nodenr].node_mem = node->mem;

        if (!qtest_enabled()) {

            warn_report("Parameter -numa node,mem is deprecated,"

hw/i386/pc.c

+0 −1
Original line number Diff line number Diff line
@@ -1980,7 +1980,6 @@ 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_MAX_RAM_BELOW_4G, "size",

hw/i386/pc_piix.c

+1 −0
Original line number Diff line number Diff line
@@ -441,6 +441,7 @@ 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);

}