Re: [PATCH v5] 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 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(a)redhat.com&gt; Reviewed-by: Michal Privoznik <mprivozn(a)redhat.com&gt; Reviewed-by: Michael S. Tsirkin <mst(a)redhat.com&gt; Reviewed-by: Greg Kurz <groug(a)kaod.org&gt;

--- v1: - rebased on top of current master - move compat mode from 4.2 to 5.0 v2: - move deprecation 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 v5: - add "\n" at the end of error_append_hint() - fix gramar/spelling in moved deprecation text CC: peter.maydell(a)linaro.org CC: ehabkost(a)redhat.com CC: marcel.apfelbaum(a)gmail.com CC: mst(a)redhat.com CC: pbonzini(a)redhat.com CC: rth(a)twiddle.net CC: david(a)gibson.dropbear.id.au CC: libvir-list(a)redhat.com CC: qemu-arm(a)nongnu.org CC: qemu-ppc(a)nongnu.org CC: eblake(a)redhat.com CC: groug(a)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..72666ac764 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 The ``-realtime mlock=on|off`` argument has been replaced by the ``-overcommit mem-lock=on|off`` argument.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`` 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. 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..a935640962 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\n"); + 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