diff mbox series

[v18,2/8] numa: Extend CLI to provide memory latency and bandwidth information

Message ID 20191127082613.22903-3-tao3.xu@intel.com
State New
Headers show
Series Build ACPI Heterogeneous Memory Attribute Table (HMAT) | expand

Commit Message

Tao Xu Nov. 27, 2019, 8:26 a.m. UTC
From: Liu Jingqi <jingqi.liu@intel.com>

Add -numa hmat-lb option to provide System Locality Latency and
Bandwidth Information. These memory attributes help to build
System Locality Latency and Bandwidth Information Structure(s)
in ACPI Heterogeneous Memory Attribute Table (HMAT).

Signed-off-by: Liu Jingqi <jingqi.liu@intel.com>
Signed-off-by: Tao Xu <tao3.xu@intel.com>
---

Changes in v18:
    - Use qapi type uint64 and only nanosecond for latency (Markus)

Changes in v17:
    - Add check when user input latency or bandwidth 0, the
      lb_info_provided should also be 0. Because in ACPI 6.3 5.2.27.4,
      0 means the corresponding latency or bandwidth information is
      not provided.
    - Fix the infinite loop when node->latency is 0.

Changes in v16:
    - Initialize HMAT_LB_Data lb_data (Igor)
    - Remove punctuation from error_setg (Igor)
    - Correct some description (Igor)
    - Drop statement about max value (Igor)
    - Simplify struct HMAT_LB_Info and related code, unify latency
      and bandwidth (Igor)

Changes in v15:
    - Change the QAPI version tag to 5.0 (Eric)
---
 hw/core/numa.c        | 181 ++++++++++++++++++++++++++++++++++++++++++
 include/sysemu/numa.h |  53 +++++++++++++
 qapi/machine.json     |  94 +++++++++++++++++++++-
 qemu-options.hx       |  47 ++++++++++-
 4 files changed, 372 insertions(+), 3 deletions(-)

Comments

Markus Armbruster Nov. 27, 2019, 9:48 a.m. UTC | #1
Tao Xu <tao3.xu@intel.com> writes:

> From: Liu Jingqi <jingqi.liu@intel.com>
>
> Add -numa hmat-lb option to provide System Locality Latency and
> Bandwidth Information. These memory attributes help to build
> System Locality Latency and Bandwidth Information Structure(s)
> in ACPI Heterogeneous Memory Attribute Table (HMAT).

Please mention this requires -machine hmat=on.

> Signed-off-by: Liu Jingqi <jingqi.liu@intel.com>
> Signed-off-by: Tao Xu <tao3.xu@intel.com>
[...]
> diff --git a/qapi/machine.json b/qapi/machine.json
> index 27d0e37534..c741649d7b 100644
> --- a/qapi/machine.json
> +++ b/qapi/machine.json
> @@ -426,10 +426,12 @@
>  #
>  # @cpu: property based CPU(s) to node mapping (Since: 2.10)
>  #
> +# @hmat-lb: memory latency and bandwidth information (Since: 5.0)
> +#
>  # Since: 2.1
>  ##
>  { 'enum': 'NumaOptionsType',
> -  'data': [ 'node', 'dist', 'cpu' ] }
> +  'data': [ 'node', 'dist', 'cpu', 'hmat-lb' ] }
>  
>  ##
>  # @NumaOptions:
> @@ -444,7 +446,8 @@
>    'data': {
>      'node': 'NumaNodeOptions',
>      'dist': 'NumaDistOptions',
> -    'cpu': 'NumaCpuOptions' }}
> +    'cpu': 'NumaCpuOptions',
> +    'hmat-lb': 'NumaHmatLBOptions' }}
>  
>  ##
>  # @NumaNodeOptions:
> @@ -557,6 +560,93 @@
>     'base': 'CpuInstanceProperties',
>     'data' : {} }
>  
> +##
> +# @HmatLBMemoryHierarchy:
> +#
> +# The memory hierarchy in the System Locality Latency
> +# and Bandwidth Information Structure of HMAT (Heterogeneous
> +# Memory Attribute Table)
> +#
> +# For more information about @HmatLBMemoryHierarchy see
> +# the chapter 5.2.27.4: Table 5-146: Field "Flags" of ACPI 6.3 spec.

Comma before "see", and s/the chapter/chapter/.

Suggest to fill these paragraphs more evenly:

   # The memory hierarchy in the System Locality Latency and Bandwidth
   # Information Structure of HMAT (Heterogeneous Memory Attribute Table)
   #
   # For more information about @HmatLBMemoryHierarchy, see chapter
   # 5.2.27.4: Table 5-146: Field "Flags" of ACPI 6.3 spec.

> +#
> +# @memory: the structure represents the memory performance
> +#
> +# @first-level: first level of memory side cache
> +#
> +# @second-level: second level of memory side cache
> +#
> +# @third-level: third level of memory side cache
> +#
> +# Since: 5.0
> +##
> +{ 'enum': 'HmatLBMemoryHierarchy',
> +  'data': [ 'memory', 'first-level', 'second-level', 'third-level' ] }
> +
> +##
> +# @HmatLBDataType:
> +#
> +# Data type in the System Locality Latency
> +# and Bandwidth Information Structure of HMAT (Heterogeneous
> +# Memory Attribute Table)
> +#
> +# For more information about @HmatLBDataType see
> +# the chapter 5.2.27.4: Table 5-146:  Field "Data Type" of ACPI 6.3 spec.

Likewise.

> +#
> +# @access-latency: access latency (nanoseconds)
> +#
> +# @read-latency: read latency (nanoseconds)
> +#
> +# @write-latency: write latency (nanoseconds)
> +#
> +# @access-bandwidth: access bandwidth (B/s)

We spell out bytes per second elsewhere in the QAPI schema.  Let's to
the same here.

> +#
> +# @read-bandwidth: read bandwidth (B/s)
> +#
> +# @write-bandwidth: write bandwidth (B/s)
> +#
> +# Since: 5.0
> +##
> +{ 'enum': 'HmatLBDataType',
> +  'data': [ 'access-latency', 'read-latency', 'write-latency',
> +            'access-bandwidth', 'read-bandwidth', 'write-bandwidth' ] }
> +
> +##
> +# @NumaHmatLBOptions:
> +#
> +# Set the system locality latency and bandwidth information
> +# between Initiator and Target proximity Domains.
> +#
> +# For more information about @NumaHmatLBOptions see
> +# the chapter 5.2.27.4: Table 5-146 of ACPI 6.3 spec.

Likewise.

> +#
> +# @initiator: the Initiator Proximity Domain.
> +#
> +# @target: the Target Proximity Domain.
> +#
> +# @hierarchy: the Memory Hierarchy. Indicates the performance
> +#             of memory or side cache.
> +#
> +# @data-type: presents the type of data, access/read/write
> +#             latency or hit latency.
> +#
> +# @latency: the value of latency from @initiator to @target proximity domain,
> +#           the latency unit is "ns(nanosecond)".
> +#
> +# @bandwidth: the value of bandwidth between @initiator and @target proximity
> +#             domain, the bandwidth unit is "B(/s)".

Break lines around column 70, please.

> +#
> +# Since: 5.0
> +##
> +{ 'struct': 'NumaHmatLBOptions',
> +    'data': {
> +    'initiator': 'uint16',
> +    'target': 'uint16',
> +    'hierarchy': 'HmatLBMemoryHierarchy',
> +    'data-type': 'HmatLBDataType',
> +    '*latency': 'uint64',
> +    '*bandwidth': 'size' }}
> +
>  ##
>  # @HostMemPolicy:
>  #
[...]
diff mbox series

Patch

diff --git a/hw/core/numa.c b/hw/core/numa.c
index e60da99293..2183c8df1f 100644
--- a/hw/core/numa.c
+++ b/hw/core/numa.c
@@ -23,6 +23,7 @@ 
  */
 
 #include "qemu/osdep.h"
+#include "qemu/units.h"
 #include "sysemu/hostmem.h"
 #include "sysemu/numa.h"
 #include "sysemu/sysemu.h"
@@ -198,6 +199,173 @@  void parse_numa_distance(MachineState *ms, NumaDistOptions *dist, Error **errp)
     ms->numa_state->have_numa_distance = true;
 }
 
+void parse_numa_hmat_lb(NumaState *numa_state, NumaHmatLBOptions *node,
+                        Error **errp)
+{
+    int i, first_bit, last_bit;
+    uint64_t max_entry, temp_base_la;
+    NodeInfo *numa_info = numa_state->nodes;
+    HMAT_LB_Info *hmat_lb =
+        numa_state->hmat_lb[node->hierarchy][node->data_type];
+    HMAT_LB_Data lb_data = {};
+    HMAT_LB_Data *lb_temp;
+
+    /* Error checking */
+    if (node->initiator > numa_state->num_nodes) {
+        error_setg(errp, "Invalid initiator=%d, it should be less than %d",
+                   node->initiator, numa_state->num_nodes);
+        return;
+    }
+    if (node->target > numa_state->num_nodes) {
+        error_setg(errp, "Invalid target=%d, it should be less than %d",
+                   node->target, numa_state->num_nodes);
+        return;
+    }
+    if (!numa_info[node->initiator].has_cpu) {
+        error_setg(errp, "Invalid initiator=%d, it isn't an "
+                   "initiator proximity domain", node->initiator);
+        return;
+    }
+    if (!numa_info[node->target].present) {
+        error_setg(errp, "The target=%d should point to an existing node",
+                   node->target);
+        return;
+    }
+
+    if (!hmat_lb) {
+        hmat_lb = g_malloc0(sizeof(*hmat_lb));
+        numa_state->hmat_lb[node->hierarchy][node->data_type] = hmat_lb;
+        hmat_lb->list = g_array_new(false, true, sizeof(HMAT_LB_Data));
+    }
+    hmat_lb->hierarchy = node->hierarchy;
+    hmat_lb->data_type = node->data_type;
+    lb_data.initiator = node->initiator;
+    lb_data.target = node->target;
+
+    if (node->data_type <= HMATLB_DATA_TYPE_WRITE_LATENCY) {
+        /* Input latency data */
+
+        if (!node->has_latency) {
+            error_setg(errp, "Missing 'latency' option");
+            return;
+        }
+        if (node->has_bandwidth) {
+            error_setg(errp, "Invalid option 'bandwidth' since "
+                       "the data type is latency");
+            return;
+        }
+
+        /* Detect duplicate configuration */
+        for (i = 0; i < hmat_lb->list->len; i++) {
+            lb_temp = &g_array_index(hmat_lb->list, HMAT_LB_Data, i);
+
+            if (node->initiator == lb_temp->initiator &&
+                node->target == lb_temp->target) {
+                error_setg(errp, "Duplicate configuration of the latency for "
+                    "initiator=%d and target=%d", node->initiator,
+                    node->target);
+                return;
+            }
+        }
+
+        hmat_lb->base = hmat_lb->base ? hmat_lb->base : UINT64_MAX;
+
+        if (node->latency) {
+            /* Calculate the temporary base and compressed latency */
+            max_entry = node->latency;
+            temp_base_la = 1;
+            while (QEMU_IS_ALIGNED(max_entry, 10)) {
+                max_entry /= 10;
+                temp_base_la *= 10;
+            }
+
+            /* Calculate the max compressed latency */
+            hmat_lb->base = MIN(hmat_lb->base, temp_base_la);
+            max_entry = node->latency / hmat_lb->base;
+            hmat_lb->range_bitmap = MAX(hmat_lb->range_bitmap, max_entry);
+
+            /*
+             * For latency hmat_lb->range_bitmap record the max compressed
+             * latency which should be less than 0xFFFF (UINT16_MAX)
+             */
+            if (hmat_lb->range_bitmap >= UINT16_MAX) {
+                error_setg(errp, "Latency %" PRIu64 " between initiator=%d and "
+                        "target=%d should not differ from previously entered "
+                        "min or max values on more than %d", node->latency,
+                        node->initiator, node->target, UINT16_MAX - 1);
+                return;
+            }
+
+            /*
+             * Set lb_info_provided bit 0 as 1,
+             * latency information is provided
+             */
+            numa_info[node->target].lb_info_provided |= BIT(0);
+        }
+        lb_data.data = node->latency;
+    } else if (node->data_type >= HMATLB_DATA_TYPE_ACCESS_BANDWIDTH) {
+        /* Input bandwidth data */
+
+        if (!node->has_bandwidth) {
+            error_setg(errp, "Missing 'bandwidth' option");
+            return;
+        }
+        if (node->has_latency) {
+            error_setg(errp, "Invalid option 'latency' since "
+                       "the data type is bandwidth");
+            return;
+        }
+        if (!QEMU_IS_ALIGNED(node->bandwidth, MiB)) {
+            error_setg(errp, "Bandwidth %" PRIu64 " between initiator=%d and "
+                       "target=%d should be 1MB aligned", node->bandwidth,
+                       node->initiator, node->target);
+            return;
+        }
+
+        /* Detect duplicate configuration */
+        for (i = 0; i < hmat_lb->list->len; i++) {
+            lb_temp = &g_array_index(hmat_lb->list, HMAT_LB_Data, i);
+
+            if (node->initiator == lb_temp->initiator &&
+                node->target == lb_temp->target) {
+                error_setg(errp, "Duplicate configuration of the bandwidth for "
+                    "initiator=%d and target=%d", node->initiator,
+                    node->target);
+                return;
+            }
+        }
+
+        hmat_lb->range_bitmap |= node->bandwidth;
+        first_bit = ctz64(hmat_lb->range_bitmap);
+        hmat_lb->base = UINT64_C(1) << first_bit;
+        max_entry = node->bandwidth / hmat_lb->base;
+        last_bit = 64 - clz64(hmat_lb->range_bitmap);
+
+        /*
+         * For bandwidth, first_bit record the base unit of bandwidth bits,
+         * last_bit record the last bit of the max bandwidth. The max compressed
+         * bandwidth should be less than 0xFFFF (UINT16_MAX)
+         */
+        if ((last_bit - first_bit) > UINT16_BITS || max_entry >= UINT16_MAX) {
+            error_setg(errp, "Bandwidth %" PRIu64 " between initiator=%d and "
+                       "target=%d should not differ from previously entered "
+                       "values on more than %d", node->bandwidth,
+                       node->initiator, node->target, UINT16_MAX - 1);
+            return;
+        }
+
+        /* Set lb_info_provided bit 1 as 1, bandwidth information is provided */
+        if (node->bandwidth) {
+            numa_info[node->target].lb_info_provided |= BIT(1);
+        }
+        lb_data.data = node->bandwidth;
+    } else {
+        assert(0);
+    }
+
+    g_array_append_val(hmat_lb->list, lb_data);
+}
+
 void set_numa_options(MachineState *ms, NumaOptions *object, Error **errp)
 {
     Error *err = NULL;
@@ -236,6 +404,19 @@  void set_numa_options(MachineState *ms, NumaOptions *object, Error **errp)
         machine_set_cpu_numa_node(ms, qapi_NumaCpuOptions_base(&object->u.cpu),
                                   &err);
         break;
+    case NUMA_OPTIONS_TYPE_HMAT_LB:
+        if (!ms->numa_state->hmat_enabled) {
+            error_setg(errp, "ACPI Heterogeneous Memory Attribute Table "
+                       "(HMAT) is disabled, enable it with -machine hmat=on "
+                       "before using any of hmat specific options");
+            return;
+        }
+
+        parse_numa_hmat_lb(ms->numa_state, &object->u.hmat_lb, &err);
+        if (err) {
+            goto end;
+        }
+        break;
     default:
         abort();
     }
diff --git a/include/sysemu/numa.h b/include/sysemu/numa.h
index 788cbec7a2..70f93c83d7 100644
--- a/include/sysemu/numa.h
+++ b/include/sysemu/numa.h
@@ -14,11 +14,34 @@  struct CPUArchId;
 #define NUMA_DISTANCE_MAX         254
 #define NUMA_DISTANCE_UNREACHABLE 255
 
+/* the value of AcpiHmatLBInfo flags */
+enum {
+    HMAT_LB_MEM_MEMORY           = 0,
+    HMAT_LB_MEM_CACHE_1ST_LEVEL  = 1,
+    HMAT_LB_MEM_CACHE_2ND_LEVEL  = 2,
+    HMAT_LB_MEM_CACHE_3RD_LEVEL  = 3,
+    HMAT_LB_LEVELS   /* must be the last entry */
+};
+
+/* the value of AcpiHmatLBInfo data type */
+enum {
+    HMAT_LB_DATA_ACCESS_LATENCY   = 0,
+    HMAT_LB_DATA_READ_LATENCY     = 1,
+    HMAT_LB_DATA_WRITE_LATENCY    = 2,
+    HMAT_LB_DATA_ACCESS_BANDWIDTH = 3,
+    HMAT_LB_DATA_READ_BANDWIDTH   = 4,
+    HMAT_LB_DATA_WRITE_BANDWIDTH  = 5,
+    HMAT_LB_TYPES   /* must be the last entry */
+};
+
+#define UINT16_BITS       16
+
 struct NodeInfo {
     uint64_t node_mem;
     struct HostMemoryBackend *node_memdev;
     bool present;
     bool has_cpu;
+    uint8_t lb_info_provided;
     uint16_t initiator;
     uint8_t distance[MAX_NODES];
 };
@@ -28,6 +51,31 @@  struct NumaNodeMem {
     uint64_t node_plugged_mem;
 };
 
+struct HMAT_LB_Data {
+    uint8_t     initiator;
+    uint8_t     target;
+    uint64_t    data;
+};
+typedef struct HMAT_LB_Data HMAT_LB_Data;
+
+struct HMAT_LB_Info {
+    /* Indicates it's memory or the specified level memory side cache. */
+    uint8_t     hierarchy;
+
+    /* Present the type of data, access/read/write latency or bandwidth. */
+    uint8_t     data_type;
+
+    /* The range bitmap of bandwidth for calculating common base */
+    uint64_t    range_bitmap;
+
+    /* The common base unit for latencies or bandwidths */
+    uint64_t    base;
+
+    /* Array to store the latencies or bandwidths */
+    GArray      *list;
+};
+typedef struct HMAT_LB_Info HMAT_LB_Info;
+
 struct NumaState {
     /* Number of NUMA nodes */
     int num_nodes;
@@ -40,11 +88,16 @@  struct NumaState {
 
     /* NUMA nodes information */
     NodeInfo nodes[MAX_NODES];
+
+    /* NUMA nodes HMAT Locality Latency and Bandwidth Information */
+    HMAT_LB_Info *hmat_lb[HMAT_LB_LEVELS][HMAT_LB_TYPES];
 };
 typedef struct NumaState NumaState;
 
 void set_numa_options(MachineState *ms, NumaOptions *object, Error **errp);
 void parse_numa_opts(MachineState *ms);
+void parse_numa_hmat_lb(NumaState *numa_state, NumaHmatLBOptions *node,
+                        Error **errp);
 void numa_complete_configuration(MachineState *ms);
 void query_numa_node_mem(NumaNodeMem node_mem[], MachineState *ms);
 extern QemuOptsList qemu_numa_opts;
diff --git a/qapi/machine.json b/qapi/machine.json
index 27d0e37534..c741649d7b 100644
--- a/qapi/machine.json
+++ b/qapi/machine.json
@@ -426,10 +426,12 @@ 
 #
 # @cpu: property based CPU(s) to node mapping (Since: 2.10)
 #
+# @hmat-lb: memory latency and bandwidth information (Since: 5.0)
+#
 # Since: 2.1
 ##
 { 'enum': 'NumaOptionsType',
-  'data': [ 'node', 'dist', 'cpu' ] }
+  'data': [ 'node', 'dist', 'cpu', 'hmat-lb' ] }
 
 ##
 # @NumaOptions:
@@ -444,7 +446,8 @@ 
   'data': {
     'node': 'NumaNodeOptions',
     'dist': 'NumaDistOptions',
-    'cpu': 'NumaCpuOptions' }}
+    'cpu': 'NumaCpuOptions',
+    'hmat-lb': 'NumaHmatLBOptions' }}
 
 ##
 # @NumaNodeOptions:
@@ -557,6 +560,93 @@ 
    'base': 'CpuInstanceProperties',
    'data' : {} }
 
+##
+# @HmatLBMemoryHierarchy:
+#
+# The memory hierarchy in the System Locality Latency
+# and Bandwidth Information Structure of HMAT (Heterogeneous
+# Memory Attribute Table)
+#
+# For more information about @HmatLBMemoryHierarchy see
+# the chapter 5.2.27.4: Table 5-146: Field "Flags" of ACPI 6.3 spec.
+#
+# @memory: the structure represents the memory performance
+#
+# @first-level: first level of memory side cache
+#
+# @second-level: second level of memory side cache
+#
+# @third-level: third level of memory side cache
+#
+# Since: 5.0
+##
+{ 'enum': 'HmatLBMemoryHierarchy',
+  'data': [ 'memory', 'first-level', 'second-level', 'third-level' ] }
+
+##
+# @HmatLBDataType:
+#
+# Data type in the System Locality Latency
+# and Bandwidth Information Structure of HMAT (Heterogeneous
+# Memory Attribute Table)
+#
+# For more information about @HmatLBDataType see
+# the chapter 5.2.27.4: Table 5-146:  Field "Data Type" of ACPI 6.3 spec.
+#
+# @access-latency: access latency (nanoseconds)
+#
+# @read-latency: read latency (nanoseconds)
+#
+# @write-latency: write latency (nanoseconds)
+#
+# @access-bandwidth: access bandwidth (B/s)
+#
+# @read-bandwidth: read bandwidth (B/s)
+#
+# @write-bandwidth: write bandwidth (B/s)
+#
+# Since: 5.0
+##
+{ 'enum': 'HmatLBDataType',
+  'data': [ 'access-latency', 'read-latency', 'write-latency',
+            'access-bandwidth', 'read-bandwidth', 'write-bandwidth' ] }
+
+##
+# @NumaHmatLBOptions:
+#
+# Set the system locality latency and bandwidth information
+# between Initiator and Target proximity Domains.
+#
+# For more information about @NumaHmatLBOptions see
+# the chapter 5.2.27.4: Table 5-146 of ACPI 6.3 spec.
+#
+# @initiator: the Initiator Proximity Domain.
+#
+# @target: the Target Proximity Domain.
+#
+# @hierarchy: the Memory Hierarchy. Indicates the performance
+#             of memory or side cache.
+#
+# @data-type: presents the type of data, access/read/write
+#             latency or hit latency.
+#
+# @latency: the value of latency from @initiator to @target proximity domain,
+#           the latency unit is "ns(nanosecond)".
+#
+# @bandwidth: the value of bandwidth between @initiator and @target proximity
+#             domain, the bandwidth unit is "B(/s)".
+#
+# Since: 5.0
+##
+{ 'struct': 'NumaHmatLBOptions',
+    'data': {
+    'initiator': 'uint16',
+    'target': 'uint16',
+    'hierarchy': 'HmatLBMemoryHierarchy',
+    'data-type': 'HmatLBDataType',
+    '*latency': 'uint64',
+    '*bandwidth': 'size' }}
+
 ##
 # @HostMemPolicy:
 #
diff --git a/qemu-options.hx b/qemu-options.hx
index 63f6b33322..6a9f738dc5 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -168,16 +168,19 @@  DEF("numa", HAS_ARG, QEMU_OPTION_numa,
     "-numa node[,mem=size][,cpus=firstcpu[-lastcpu]][,nodeid=node][,initiator=node]\n"
     "-numa node[,memdev=id][,cpus=firstcpu[-lastcpu]][,nodeid=node][,initiator=node]\n"
     "-numa dist,src=source,dst=destination,val=distance\n"
-    "-numa cpu,node-id=node[,socket-id=x][,core-id=y][,thread-id=z]\n",
+    "-numa cpu,node-id=node[,socket-id=x][,core-id=y][,thread-id=z]\n"
+    "-numa hmat-lb,initiator=node,target=node,hierarchy=memory|first-level|second-level|third-level,data-type=access-latency|read-latency|write-latency[,latency=lat][,bandwidth=bw]\n",
     QEMU_ARCH_ALL)
 STEXI
 @item -numa node[,mem=@var{size}][,cpus=@var{firstcpu}[-@var{lastcpu}]][,nodeid=@var{node}][,initiator=@var{initiator}]
 @itemx -numa node[,memdev=@var{id}][,cpus=@var{firstcpu}[-@var{lastcpu}]][,nodeid=@var{node}][,initiator=@var{initiator}]
 @itemx -numa dist,src=@var{source},dst=@var{destination},val=@var{distance}
 @itemx -numa cpu,node-id=@var{node}[,socket-id=@var{x}][,core-id=@var{y}][,thread-id=@var{z}]
+@itemx -numa hmat-lb,initiator=@var{node},target=@var{node},hierarchy=@var{hierarchy},data-type=@var{tpye}[,latency=@var{lat}][,bandwidth=@var{bw}]
 @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.
+Set the ACPI Heterogeneous Memory Attributes for the given nodes.
 
 Legacy VCPU assignment uses @samp{cpus} option where
 @var{firstcpu} and @var{lastcpu} are CPU indexes. Each
@@ -256,6 +259,48 @@  specified resources, it just assigns existing resources to NUMA
 nodes. This means that one still has to use the @option{-m},
 @option{-smp} options to allocate RAM and VCPUs respectively.
 
+Use @samp{hmat-lb} to set System Locality Latency and Bandwidth Information
+between initiator and target NUMA nodes in ACPI Heterogeneous Attribute Memory Table (HMAT).
+Initiator NUMA node can create memory requests, usually it has one or more processors.
+Target NUMA node contains addressable memory.
+
+In @samp{hmat-lb} option, @var{node} are NUMA node IDs. @var{hierarchy} is the memory
+hierarchy of the target NUMA node: if @var{hierarchy} is 'memory', the structure
+represents the memory performance; if @var{hierarchy} is 'first-level|second-level|third-level',
+this structure represents aggregated performance of memory side caches for each domain.
+@var{type} of 'data-type' is type of data represented by this structure instance:
+if 'hierarchy' is 'memory', 'data-type' is 'access|read|write' latency or 'access|read|write'
+bandwidth of the target memory; if 'hierarchy' is 'first-level|second-level|third-level',
+'data-type' is 'access|read|write' hit latency or 'access|read|write' hit bandwidth of the
+target memory side cache.
+
+@var{lat} is latency value in nanoseconds. @var{bw} is bandwidth value,
+the possible value and units are NUM[M|G|T], mean that the bandwidth value are
+NUM byte (or MB/s, GB/s or TB/s depending on used suffix). And if input bandwidth
+value without any unit, the unit will be B/s. Note that if latency or bandwidth
+value is 0, means the corresponding latency or bandwidth information is not provided.
+
+For example, the following options describe 2 NUMA nodes. Node 0 has 2 cpus and
+a ram, node 1 has only a ram. The processors in node 0 access memory in node
+0 with access-latency 5 nanoseconds, access-bandwidth is 200 MB/s;
+The processors in NUMA node 0 access memory in NUMA node 1 with access-latency 10
+nanoseconds, access-bandwidth is 100 MB/s.
+@example
+-machine hmat=on \
+-m 2G \
+-object memory-backend-ram,size=1G,id=m0 \
+-object memory-backend-ram,size=1G,id=m1 \
+-smp 2 \
+-numa node,nodeid=0,memdev=m0 \
+-numa node,nodeid=1,memdev=m1,initiator=0 \
+-numa cpu,node-id=0,socket-id=0 \
+-numa cpu,node-id=0,socket-id=1 \
+-numa hmat-lb,initiator=0,target=0,hierarchy=memory,data-type=access-latency,latency=5 \
+-numa hmat-lb,initiator=0,target=0,hierarchy=memory,data-type=access-bandwidth,bandwidth=200M \
+-numa hmat-lb,initiator=0,target=1,hierarchy=memory,data-type=access-latency,latency=10 \
+-numa hmat-lb,initiator=0,target=1,hierarchy=memory,data-type=access-bandwidth,bandwidth=100M
+@end example
+
 ETEXI
 
 DEF("add-fd", HAS_ARG, QEMU_OPTION_add_fd,