On Mon, Apr 03, 2017 at 10:38:51AM +0200, Andrew Jones wrote:
> On Sat, Apr 01, 2017 at 06:25:26PM +0800, He Chen wrote:
> > Current, QEMU does not provide a clear command to set vNUMA distance for
> > guest although we already have `-numa` command to set vNUMA nodes.
> >
> > vNUMA distance makes sense in certain scenario.
> > But now, if we create a guest that has 4 vNUMA nodes, when we check NUMA
> > info via `numactl -H`, we will see:
> >
> > node distance:
> > node 0 1 2 3
> > 0: 10 20 20 20
> > 1: 20 10 20 20
> > 2: 20 20 10 20
> > 3: 20 20 20 10
> >
> > Guest kernel regards all local node as distance 10, and all remote node
> > as distance 20 when there is no SLIT table since QEMU doesn't build it.
> > It looks like a little strange when you have seen the distance in an
> > actual physical machine that contains 4 NUMA nodes. My machine shows:
> >
> > node distance:
> > node 0 1 2 3
> > 0: 10 21 31 41
> > 1: 21 10 21 31
> > 2: 31 21 10 21
> > 3: 41 31 21 10
> >
> > To set vNUMA distance, guest should see a complete SLIT table.
> > I found QEMU has provide `-acpitable` command that allows users to add
> > a ACPI table into guest, but it requires users building ACPI table by
> > themselves first. Using `-acpitable` to add a SLIT table may be not so
> > straightforward or flexible, imagine that when the vNUMA configuration
> > is changes and we need to generate another SLIT table manually. It may
> > not be friendly to users or upper software like libvirt.
> >
> > This patch is going to add SLIT table support in QEMU, and provides
> > additional option `dist` for command `-numa` to allow user set vNUMA
> > distance by QEMU command.
> >
> > With this patch, when a user wants to create a guest that contains
> > several vNUMA nodes and also wants to set distance among those nodes,
> > the QEMU command would like:
> >
> > ```
> > -numa node,nodeid=0,cpus=0 \
> > -numa node,nodeid=1,cpus=1 \
> > -numa node,nodeid=2,cpus=2 \
> > -numa node,nodeid=3,cpus=3 \
> > -numa dist,src=0,dst=0,val=10 \
> > -numa dist,src=0,dst=1,val=21 \
> > -numa dist,src=0,dst=2,val=31 \
> > -numa dist,src=0,dst=3,val=41 \
> > -numa dist,src=1,dst=0,val=21 \
> > -numa dist,src=1,dst=1,val=10 \
> > -numa dist,src=1,dst=2,val=21 \
> > -numa dist,src=1,dst=3,val=31 \
> > -numa dist,src=2,dst=0,val=31 \
> > -numa dist,src=2,dst=1,val=21 \
> > -numa dist,src=2,dst=2,val=10 \
> > -numa dist,src=2,dst=3,val=21 \
> > -numa dist,src=3,dst=0,val=41 \
> > -numa dist,src=3,dst=1,val=31 \
> > -numa dist,src=3,dst=2,val=21 \
> > -numa dist,src=3,dst=3,val=10 \
> > ```
> >
> > Signed-off-by: He Chen <he.c...@linux.intel.com>
> > ---
> > hw/acpi/aml-build.c | 26 +++++++++++++++++
> > hw/i386/acpi-build.c | 2 ++
> > include/hw/acpi/aml-build.h | 1 +
> > include/sysemu/numa.h | 1 +
> > include/sysemu/sysemu.h | 4 +++
> > numa.c | 70
> > +++++++++++++++++++++++++++++++++++++++++++++
> > qapi-schema.json | 28 ++++++++++++++++--
> > qemu-options.hx | 11 ++++++-
> > 8 files changed, 140 insertions(+), 3 deletions(-)
> >
> > diff --git a/hw/acpi/aml-build.c b/hw/acpi/aml-build.c
> > index c6f2032..410b30e 100644
> > --- a/hw/acpi/aml-build.c
> > +++ b/hw/acpi/aml-build.c
> > @@ -24,6 +24,7 @@
> > #include "hw/acpi/aml-build.h"
> > #include "qemu/bswap.h"
> > #include "qemu/bitops.h"
> > +#include "sysemu/numa.h"
> >
> > static GArray *build_alloc_array(void)
> > {
> > @@ -1609,3 +1610,28 @@ void build_srat_memory(AcpiSratMemoryAffinity
> > *numamem, uint64_t base,
> > numamem->base_addr = cpu_to_le64(base);
> > numamem->range_length = cpu_to_le64(len);
> > }
> > +
> > +/*
> > + * ACPI spec 5.2.17 System Locality Distance Information Table
> > + * (Revision 2.0 or later)
> > + */
> > +void build_slit(GArray *table_data, BIOSLinker *linker)
> > +{
> > + int slit_start, i, j;
> > + slit_start = table_data->len;
> > +
> > + acpi_data_push(table_data, sizeof(AcpiTableHeader));
> > +
> > + build_append_int_noprefix(table_data, nb_numa_nodes, 8);
> > + for (i = 0; i < nb_numa_nodes; i++) {
> > + for (j = 0; j < nb_numa_nodes; j++) {
> > + build_append_int_noprefix(table_data,
> > numa_info[i].distance[j], 1);
> > + }
> > + }
> > +
> > + build_header(linker, table_data,
> > + (void *)(table_data->data + slit_start),
> > + "SLIT",
> > + table_data->len - slit_start, 1, NULL, NULL);
> > +}
> > +
> > diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
> > index 2073108..12730ea 100644
> > --- a/hw/i386/acpi-build.c
> > +++ b/hw/i386/acpi-build.c
> > @@ -2678,6 +2678,8 @@ void acpi_build(AcpiBuildTables *tables, MachineState
> > *machine)
> > if (pcms->numa_nodes) {
> > acpi_add_table(table_offsets, tables_blob);
> > build_srat(tables_blob, tables->linker, machine);
> > + acpi_add_table(table_offsets, tables_blob);
> > + build_slit(tables_blob, tables->linker);
> > }
> > if (acpi_get_mcfg(&mcfg)) {
> > acpi_add_table(table_offsets, tables_blob);
> > diff --git a/include/hw/acpi/aml-build.h b/include/hw/acpi/aml-build.h
> > index 00c21f1..329a0d0 100644
> > --- a/include/hw/acpi/aml-build.h
> > +++ b/include/hw/acpi/aml-build.h
> > @@ -389,4 +389,5 @@ GCC_FMT_ATTR(2, 3);
> > void build_srat_memory(AcpiSratMemoryAffinity *numamem, uint64_t base,
> > uint64_t len, int node, MemoryAffinityFlags flags);
> >
> > +void build_slit(GArray *table_data, BIOSLinker *linker);
> > #endif
> > diff --git a/include/sysemu/numa.h b/include/sysemu/numa.h
> > index 8f09dcf..2f7a941 100644
> > --- a/include/sysemu/numa.h
> > +++ b/include/sysemu/numa.h
> > @@ -21,6 +21,7 @@ typedef struct node_info {
> > struct HostMemoryBackend *node_memdev;
> > bool present;
> > QLIST_HEAD(, numa_addr_range) addr; /* List to store address ranges */
> > + uint8_t distance[MAX_NODES];
> > } NodeInfo;
> >
> > extern NodeInfo numa_info[MAX_NODES];
> > diff --git a/include/sysemu/sysemu.h b/include/sysemu/sysemu.h
> > index 576c7ce..6999545 100644
> > --- a/include/sysemu/sysemu.h
> > +++ b/include/sysemu/sysemu.h
> > @@ -169,6 +169,10 @@ extern int mem_prealloc;
> >
> > #define MAX_NODES 128
> > #define NUMA_NODE_UNASSIGNED MAX_NODES
> > +#define NUMA_DISTANCE_MIN 10
> > +#define NUMA_DISTANCE_DEFAULT 20
> > +#define NUMA_DISTANCE_MAX 254
> > +#define NUMA_DISTANCE_UNREACHABLE 255
> >
> > #define MAX_OPTION_ROMS 16
> > typedef struct QEMUOptionRom {
> > diff --git a/numa.c b/numa.c
> > index e01cb54..421c383 100644
> > --- a/numa.c
> > +++ b/numa.c
> > @@ -212,6 +212,40 @@ static void numa_node_parse(NumaNodeOptions *node,
> > QemuOpts *opts, Error **errp)
> > max_numa_nodeid = MAX(max_numa_nodeid, nodenr + 1);
> > }
> >
> > +static void numa_distance_parse(NumaDistOptions *dist, QemuOpts *opts,
> > Error **errp)
> > +{
> > + uint16_t src = dist->src;
> > + uint16_t dst = dist->dst;
> > + uint8_t val = dist->val;
> > +
> > + if (!numa_info[src].present || !numa_info[dst].present) {
> > + error_setg(errp, "Source/Destination NUMA node is missing. "
> > + "Please use '-numa node' option to declare it first.");
> > + return;
> > + }
> > +
> > + if (src >= MAX_NODES || dst >= MAX_NODES) {
> > + error_setg(errp, "Max number of NUMA nodes reached: %"
> > + PRIu16 "", src > dst ? src : dst);
> > + return;
> > + }
> > +
> > + if (val < NUMA_DISTANCE_MIN) {
> > + error_setg(errp, "NUMA distance (%" PRIu8 ") is invalid, "
> > + "it should be larger than %d.",
> > + val, NUMA_DISTANCE_MIN);
> > + return;
> > + }
> > +
> > + if (src == dst && val != NUMA_DISTANCE_MIN) {
> > + error_setg(errp, "Local distance of node %d should be %d.",
> > + src, NUMA_DISTANCE_MIN);
> > + return;
> > + }
> > +
> > + numa_info[src].distance[dst] = val;
> > +}
> > +
> > static int parse_numa(void *opaque, QemuOpts *opts, Error **errp)
> > {
> > NumaOptions *object = NULL;
> > @@ -235,6 +269,12 @@ static int parse_numa(void *opaque, QemuOpts *opts,
> > Error **errp)
> > }
> > nb_numa_nodes++;
> > break;
> > + case NUMA_OPTIONS_TYPE_DIST:
> > + numa_distance_parse(&object->u.dist, opts, &err);
> > + if (err) {
> > + goto end;
> > + }
> > + break;
> > default:
> > abort();
> > }
> > @@ -294,6 +334,35 @@ static void validate_numa_cpus(void)
> > g_free(seen_cpus);
> > }
> >
> > +static void validate_numa_distance(void)
> > +{
> > + int src, dst;
> > + bool have_distance = false;
> > +
> > + for (src = 0; src < nb_numa_nodes; src++) {
> > + for (dst = 0; dst < nb_numa_nodes; dst++) {
> > + if (numa_info[src].present &&
> > + numa_info[src].distance[dst] != 0)
> > + have_distance = true;
> > + }
> > + }
> > +
> > + if (!have_distance)
> > + return;
> > +
> > + for (src = 0; src < nb_numa_nodes; src++) {
> > + for (dst = 0; dst < nb_numa_nodes; dst++) {
> > + if (numa_info[src].present &&
> > + numa_info[src].distance[dst] == 0) {
> > + error_report("The distance between node %d and %d is
> > missing, "
> > + "please provide the complete NUMA distance
> > information.",
> > + src, dst);
> > + exit(EXIT_FAILURE);
> > + }
> > + }
> > + }
> > +}
>
> This validation is stricter than what Eduardo and I agreed was sufficient.
> This says if any distance is given, they must all be given. We agreed that
> the symmetrical shortcut was probably OK, but if any asymmetrical distance
> is given, then they must all be given. Here a couple examples
>
> Given:
> A -> B : 25
> A -> C : 35
> A -> D : 45
> B -> C : 25
> B -> D : 35
> C -> D : 25
>
> The above is OK. All reverse directions are assumed symmetrical.
>
> Given:
> A -> B : 25
> A -> C : 35
> A -> D : 45
> B -> C : 25
> B -> D : 35
> C -> D : 25
> D -> C : 35
>
> The above is not OK, as C -> D and D -> C are given asymmetrical
> distances, but no others are. We can no longer trust that the user meant
> the rest are symmetrical, so all must be given now.
>
> We should also ensure that when even one node pair's distance is given,
> then all unique node pair's must have a distance given.
>
> I've also attempted to describe this below as a suggestion for the
> documentation.
>
Thanks for your clear explain, I will cook a better patch soon.
> > +
> > void parse_numa_opts(MachineClass *mc)
> > {
> > int i;
> > @@ -390,6 +459,7 @@ void parse_numa_opts(MachineClass *mc)
> > }
> >
> > validate_numa_cpus();
> > + validate_numa_distance();
> > } else {
> > numa_set_mem_node_id(0, ram_size, 0);
> > }
> > diff --git a/qapi-schema.json b/qapi-schema.json
> > index 32b4a4b..b432e13 100644
> > --- a/qapi-schema.json
> > +++ b/qapi-schema.json
> > @@ -5644,10 +5644,14 @@
> > ##
> > # @NumaOptionsType:
> > #
> > +# @node: NUMA nodes configuration
> > +#
> > +# @dist: NUMA distance configuration
> > +#
> > # Since: 2.1
> > ##
> > { 'enum': 'NumaOptionsType',
> > - 'data': [ 'node' ] }
> > + 'data': [ 'node', 'dist' ] }
> >
> > ##
> > # @NumaOptions:
> > @@ -5660,7 +5664,8 @@
> > 'base': { 'type': 'NumaOptionsType' },
> > 'discriminator': 'type',
> > 'data': {
> > - 'node': 'NumaNodeOptions' }}
> > + 'node': 'NumaNodeOptions',
> > + 'dist': 'NumaDistOptions' }}
> >
> > ##
> > # @NumaNodeOptions:
> > @@ -5689,6 +5694,25 @@
> > '*memdev': 'str' }}
> >
> > ##
> > +# @NumaDistOptions:
> > +#
> > +# Set the distance between 2 NUMA nodes.
> > +#
> > +# @src: source NUMA node.
> > +#
> > +# @dst: destination NUMA node.
> > +#
> > +# @val: NUMA distance from source node to destination node.
> > +#
> > +# Since: 2.10
> > +##
> > +{ 'struct': 'NumaDistOptions',
> > + 'data': {
> > + 'src': 'uint16',
> > + 'dst': 'uint16',
> > + 'val': 'uint8' }}
> > +
> > +##
> > # @HostMemPolicy:
> > #
> > # Host memory policy types
> > diff --git a/qemu-options.hx b/qemu-options.hx
> > index 8dd8ee3..ce1a8ad 100644
> > --- a/qemu-options.hx
> > +++ b/qemu-options.hx
> > @@ -139,12 +139,15 @@ ETEXI
> >
> > DEF("numa", HAS_ARG, QEMU_OPTION_numa,
> > "-numa node[,mem=size][,cpus=firstcpu[-lastcpu]][,nodeid=node]\n"
> > - "-numa node[,memdev=id][,cpus=firstcpu[-lastcpu]][,nodeid=node]\n",
> > QEMU_ARCH_ALL)
> > + "-numa node[,memdev=id][,cpus=firstcpu[-lastcpu]][,nodeid=node]\n"
> > + "-numa dist,src=source,dst=destination,val=distance\n", QEMU_ARCH_ALL)
> > STEXI
> > @item -numa
> > node[,mem=@var{size}][,cpus=@var{firstcpu}[-@var{lastcpu}]][,nodeid=@var{node}]
> > @itemx -numa
> > node[,memdev=@var{id}][,cpus=@var{firstcpu}[-@var{lastcpu}]][,nodeid=@var{node}]
> > +@itemx -numa dist,src=@var{source},dst=@var{destination},val=@var{distance}
> > @findex -numa
> > Define a NUMA node and assign RAM and VCPUs to it.
> > +Set the NUMA distance from a source node to a destination node.
> >
> > @var{firstcpu} and @var{lastcpu} are CPU indexes. Each
> > @samp{cpus} option represent a contiguous range of CPU indexes
> > @@ -167,6 +170,12 @@ split equally between them.
> > @samp{mem} and @samp{memdev} are mutually exclusive. Furthermore,
> > if one node uses @samp{memdev}, all of them have to use it.
> >
> > +@var{source} and @var{destination} are NUMA node IDs.
> > +@var{distance} is the NUMA distance from @var{source} to @var{destination}.
> > +The distance from node A to node B may be different from the distance from
> > +node B to node A as the distance can to be asymmetrical. If a node is
> > +unreachable, set 255 as distance.
>
> The distance from a node to itself is always 10. If no distance values
> are given for node pairs, then the default distance of 20 is used for each
> pair. If any pair of nodes is given a distance, then all pairs must be
> given distances. Although, when distances are only given in one direction
> for each pair of nodes, then the distances in the opposite directions are
> assumed to be the same. If, however, an asymmetrical pair of distances is
> given for even one node pair, then all node pairs must be provided
> distance values for both directions, even when they are symmetrical. When
> a node is unreachable from another node, set the pair's distance to 255.
>
Thanks for your time to help me refine document here, really appreciate
it!
> > +
> > Note that the -@option{numa} option doesn't allocate any of the
> > specified resources, it just assigns existing resources to NUMA
> > nodes. This means that one still has to use the @option{-m},
> > --
> > 2.7.4
> >
> >
>
> Thanks,
> drew
>
