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[Dynamic buffer calc] Add table descriptions for dynamic buffer calculation to the documents #1664

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Mar 10, 2021
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[Dynamic buffer calc] Add table descriptions for dynamic buffer calculation to the documents #1664

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100 changes: 98 additions & 2 deletions doc/Configuration.md
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Original file line number Diff line number Diff line change
Expand Up @@ -17,13 +17,15 @@ Table of Contents
* [Cable length](#cable-length)
* [COPP_TABLE](#copp_table)
* [CRM](#crm)
* [Data Plane L3 Interfaces](#data-plane-l3-interfaces)
* [Data Plane L3 Interfaces](#data-plane-l3-interfaces)
* [DEFAULT_LOSSLESS_BUFFER_PARAMETER](#DEFAULT_LOSSLESS_BUFFER_PARAMETER)
* [Device Metadata](#device-metadata)
* [Device neighbor metada](#device-neighbor-metada)
* [DSCP_TO_TC_MAP](#dscp_to_tc_map)
* [FLEX_COUNTER_TABLE](#flex_counter_table)
* [L2 Neighbors](#l2-neighbors)
* [Loopback Interface](#loopback-interface)
* [LOSSLESS_TRAFFIC_PATTERN](#LOSSLESS_TRAFFIC_PATTERN)
* [Management Interface](#management-interface)
* [Management port](#management-port)
* [Management VRF](#management-vrf)
Expand Down Expand Up @@ -334,6 +336,8 @@ group name and IP ranges in **BGP_PEER_RANGE** table.

### BUFFER_PG

When the system is running in traditional buffer model, profiles needs to explicitly configured:

```
{
"BUFFER_PG": {
Expand All @@ -351,8 +355,32 @@ group name and IP ranges in **BGP_PEER_RANGE** table.

```

When the system is running in dynamic buffer model, profiles can be:

- either calculated dynamically according to ports' configuration and just configured as "NULL";
- or configured explicitly.

```
{
"BUFFER_PG": {
"Ethernet0|3-4": {
"profile": "NULL"
},
"Ethernet1|3-4": {
"profile": "NULL"
},
"Ethernet2|3-4": {
"profile": "[BUFFER_PROFILE|static_profile]"
}
}
}

```

### Buffer pool

When the system is running in traditional buffer model, the size of all of the buffer pools and xoff of ingress_lossless_pool need to be configured explicitly.

```
{
"BUFFER_POOL": {
Expand All @@ -377,6 +405,29 @@ group name and IP ranges in **BGP_PEER_RANGE** table.

```

When the system is running in dynamic buffer model, the size of some of the buffer pools can be omitted and will be dynamically calculated.

```
{
"BUFFER_POOL": {
"egress_lossless_pool": {
"type": "egress",
"mode": "static",
"size": "15982720"
},
"egress_lossy_pool": {
"type": "egress",
"mode": "dynamic",
},
"ingress_lossless_pool": {
"type": "ingress",
"mode": "dynamic",
}
}
}

```


### Buffer profile

Expand Down Expand Up @@ -419,6 +470,19 @@ group name and IP ranges in **BGP_PEER_RANGE** table.

```

When the system is running in dynamic buffer model and the headroom_type is dynamic, only dynamic_th needs to be configured and rest of fields can be omitted.
This kind of profiles will be handled by buffer manager and won't be applied to SAI.

```
{
{
"non_default_dynamic_th_profile": {
"dynamic_th": 1,
"headroom_type": "dynamic"
}
}
}
```

### Buffer queue

Expand Down Expand Up @@ -588,6 +652,21 @@ attributes.
```


### DEFAULT_LOSSLESS_BUFFER_PARAMETER

This table stores the default lossless buffer parameters for dynamic buffer calculation.

```
{
"DEFAULT_LOSSLESS_BUFFER_PARAMETER": {
"AZURE": {
"default_dynamic_th": "0",
"over_subscribe_ratio": "2"
}
}
}
```

### Device Metadata

The **DEVICE_METADATA** table contains only one object named
Expand All @@ -609,7 +688,8 @@ instance is supported in SONiC.
"default_pfcwd_status": "disable",
"bgp_asn": "65100",
"deployment_id": "1",
"type": "ToRRouter"
"type": "ToRRouter",
"buffer_model": "traditional"
}
}
}
Expand Down Expand Up @@ -746,6 +826,22 @@ interface objects.

```

### LOSSLESS_TRAFFIC_PATTERN

The LOSSLESS_TRAFFIC_PATTERN table stores parameters related to
lossless traffic for dynamic buffer calculation

```
{
"LOSSLESS_TRAFFIC_PATTERN": {
"AZURE": {
"mtu": "1024",
"small_packet_percentage": "100"
}
}
}
```

### Management Interface

Management interfaces are defined in **MGMT_INTERFACE** table. Object
Expand Down
61 changes: 61 additions & 0 deletions doc/swss-schema.md
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Expand Up @@ -803,6 +803,59 @@ packet_action = "drop" | "forward" | "copy" | "copy_cancel" | "trap" | "log" | "
nexthop = IP ; Nexthop IP address (Optional)
ifname = ifname ; Interface name

### BUFFER_POOL_TABLE
;Stores buffer pools

key = BUFFER_POOL_TABLE:poolname ; The poolname can be one of ingress_lossless_pool, ingress_lossy_pool, egress_lossless_pool, and egress_lossy_pool or other used-defined pools.
mode = "dynamic" / "static" ; Whether the pool uses dynamic threshold or static threshold.
type = "ingress" / "egress" ; Whether the pool serves for ingress or egress traffic
size = 1*10DIGIT ; The size of the shared buffer pool
xoff = 1*10DIGIT ; The size of the shared headroom pool. Available only for ingress_lossless_pool.

### BUFFER_PROFILE_TABLE
;Stores buffer profiles

key = BUFFER_PROFILE_TABLE:profilename ; profile name can be predefined or dynamically generated with name convention "pg_lossless_<speed>_<cable_length>_profile"
pool = reference to BUFFER_POOL_TABLE object
xon = 1*6DIGIT ; The xon threshold. The switch stops sending PFC frame when the buffer occupancy drops to this threshold.
xon_offset = 1*6DIGIT ; The xon offset. If both xon and xon_offset have been defined, the switch stops sending PFC frame
; when the buffer occupancy drops to xon or size of buffer pool size minus xon_offset, whichever is larger.
xoff = 1*6DIGIT ; The xoff threshold. The switch starts sending PFC frame when the buffer occupancy rises to this threshold.
size = 1*6DIGIT ; The reserved size of the PG or queue referencing this buffer profile.
dynamic_th = 1*2DIGIT ; For dynamic pools, representing the proportion of currently available memory in the pool the PG or queue can occupy.
; It is calculated as:
; alpha = 2 ^ dynamic_th;
; proportion = alpha / (1 + alpha)
static_th = 1*10DIGIT ; For static pools, representing the threshold in bytes the PG or queue can occupy.

### BUFFER_PG_TABLE
;Stores buffer PG (priority-groups)

key = BUFFER_PG_TABLE:port_name:pg ; The pg consists of a single number representing a single priority or two numbers connected by a dash representing a range of priorities.
; By default, PG 0 for lossy traffic and PG 3-4 for lossless traffic.
profile = reference to BUFFER_PROFILE_TABLE object

### BUFFER_QUEUE_TABLE
;Stores buffer queue

key = BUFFER_QUEUE_TABLE:port_name:queue ; The queue consists of a single number representing a single priority or two numbers connected by a dash representing a range of priorities.
; By default, queue 0-2 and 5-6 for lossy traffic and queue 3-4 for lossless traffic
profile = reference to BUFFER_PROFILE_TABLE object

### BUFFER_PORT_INGRESS_PROFILE_LIST_TABLE
;Stores per port buffer threshold on ingress side

key = BUFFER_PORT_INGRESS_PROFILE_LIST_TABLE:port_name
profile_list = a list of references to BUFFER_PROFILE_TABLE object ; Typically, for each ingress buffer pools there should be a buffer profile referencing the pool in the list.
; For example, if there are two ingress buffer pools in the system, ingress_lossless_pool and ingress_lossy_pool,
; there should be two profiles in the list: ingress_lossless_profile and ingress_lossy_profile

### BUFFER_PORT_EGRESS_PROFILE_LIST_TABLE
;Stores per port buffer threshold on egress side

key = BUFFER_PORT_EGRESS_PROFILE_LIST_TABLE:port_name
profile_list = a list of references to BUFFER_PROFILE_TABLE object ; Similar to profile_list in BUFFER_PORT_INGRESS_PROFILE_LIST_TABLE but on egress side.

## Configuration DB schema

### PORT_TABLE
Expand Down Expand Up @@ -994,6 +1047,14 @@ Stores information for physical switch ports managed by the switch chip. Ports t
key = VRF_OBJECT_TABLE|vrf_name ; vrf_name start with 'Vrf' prefix
state = "ok" ; vrf entry exist in orchagent

### BUFFER_MAX_PARAM_TABLE
;Available only when the switch is running in dynamic buffer model
;Stores the maximum available buffer on a global or per-port basis

key = BUFFER_MAX_PARAM_TABLE|ifname ; The maximum headroom of the port. The ifname should be the name of a physical port.
BUFFER_MAX_PARAM_TABLE|global ; The maximum available of the system.
mmu_size = 1*10DIGIT ; The maximum available of the system. Available only when the key is "global".
max_headroom_size = 1*10DIGIT ; The maximum headroom of the port. Available only when the key is ifname.

## Configuration files
What configuration files should we have? Do apps, orch agent each need separate files?
Expand Down