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-rw-r--r--docs/gettingstarted/developers/fib20/index.rst1
-rw-r--r--docs/gettingstarted/developers/fib20/scale.rst283
2 files changed, 284 insertions, 0 deletions
diff --git a/docs/gettingstarted/developers/fib20/index.rst b/docs/gettingstarted/developers/fib20/index.rst
index 535e15662d6..1b014524cb8 100644
--- a/docs/gettingstarted/developers/fib20/index.rst
+++ b/docs/gettingstarted/developers/fib20/index.rst
@@ -11,3 +11,4 @@ FIB 2.0 Hierarchical, Protocol, Independent
mplsfib
multicast
fastconvergence
+ scale
diff --git a/docs/gettingstarted/developers/fib20/scale.rst b/docs/gettingstarted/developers/fib20/scale.rst
new file mode 100644
index 00000000000..c97297d4adc
--- /dev/null
+++ b/docs/gettingstarted/developers/fib20/scale.rst
@@ -0,0 +1,283 @@
+.. _scale:
+
+Scale
+-----
+
+The only limiting factor on FIB scale is the amount of memory
+allocated to each heap the FIB uses, and there are 4:
+
+* The IP4 heap
+* The IP6 heap
+* The main heap
+* The stats heap
+
+
+IP4 Heap
+--------
+
+The IPv4 heap is used to allocate the memory needed for the
+data-structures within which the IPv4 prefixes are stored. Each
+table, created by the user, i.e. with;
+
+.. code-block:: console
+
+ $ ip table add 1
+
+or the default table, comprises 2 *ip4_fib_t* objects.
+The 'non-forwarding' *ip4_fib_t* contains all the entries in the table
+and, the 'forwarding' contains the entries that are matched against in
+the data-plane. The difference between the two sets are the entries
+that should not be matched in the data-plane.
+Each *ip4_fib_t* comprises an mtrie (for fast lookup in the data-plane)
+and a hash table per-prefix length (for lookup in the control plane).
+
+To see the amount of memory consumed by the IPv4 tables use:
+
+.. code-block:: console
+
+ vpp# sh ip fib mem
+ ipv4-VRF:0 mtrie:333056 hash:3523
+ ipv4-VRF:1 mtrie:333056 hash:3523
+ totals: mtrie:666112 hash:7046 all:673158
+
+ Mtrie Mheap Usage: total: 32.06M, used: 662.44K, free: 31.42M, trimmable: 31.09M
+ free chunks 3 free fastbin blks 0
+ max total allocated 32.06M
+ no traced allocations
+
+this output shows two 'empty' (i.e. no added routes) tables. Each
+mtrie uses about 150k of memory, so each table about 300k. the total
+heap usage statistics for the IP4 heap are shown at the end.
+
+
+Below the output having added 1M, 2M and 4M routes respectively:
+
+.. code-block:: console
+
+ vpp# sh ip fib mem
+ ipv4-VRF:0 mtrie:335744 hash:4695
+ totals: mtrie:335744 hash:4695 all:340439
+
+ Mtrie Mheap Usage: total: 1.00G, used: 335.20K, free: 1023.74M, trimmable: 1023.72M
+ free chunks 3 free fastbin blks 0
+ max total allocated 1.00G
+ no traced allocations
+
+.. code-block:: console
+
+ vpp# sh ip fib mem
+ ipv4-VRF:0 mtrie:5414720 hash:41177579
+ totals: mtrie:5414720 hash:41177579 all:46592299
+
+ Mtrie Mheap Usage: total: 1.00G, used: 46.87M, free: 977.19M, trimmable: 955.93M
+ free chunks 61 free fastbin blks 0
+ max total allocated 1.00G
+ no traced allocations
+
+.. code-block:: console
+
+ vpp# sh ip fib mem
+ ipv4-VRF:0 mtrie:22452608 hash:168544508
+ totals: mtrie:22452608 hash:168544508 all:190997116
+
+ Mtrie Mheap Usage: total: 1.00G, used: 198.37M, free: 825.69M, trimmable: 748.24M
+ free chunks 219 free fastbin blks 0
+ max total allocated 1.00G
+ no traced allocations
+
+VPP was started with a 1G IP4 heap.
+
+IP6 Heap
+--------
+
+The IPv6 heap is used to allocate the memory needed for the
+data-structure within which the IPv6 prefixes are stored. IPv6 also
+has the concept of forwarding and non-forwarding entries, however for
+IPv6 all the forwardind entries are stored in a single hash table
+(same goes for the non-forwarding). The key to the hash table includes
+the IPv6 table-id.
+
+To see the amount of memory consumed by the IPv4 tables use:
+
+.. code-block:: console
+
+ vpp# sh ip6 fib mem
+ IPv6 Non-Forwarding Hash Table:
+ Hash table ip6 FIB non-fwding table
+ 7 active elements 7 active buckets
+ 1 free lists
+ 0 linear search buckets
+ arena: base 7f2fe28bf000, next 803c0
+ used 525248 b (0 Mbytes) of 33554432 b (32 Mbytes)
+
+ IPv6 Forwarding Hash Table:
+ Hash table ip6 FIB fwding table
+ 7 active elements 7 active buckets
+ 1 free lists
+ 0 linear search buckets
+ arena: base 7f2fe48bf000, next 803c0
+ used 525248 b (0 Mbytes) of 33554432 b (32 Mbytes)
+
+as we scale to 128k IPv6 entries:
+
+.. code-block:: console
+
+ vpp# sh ip6 fib mem
+ IPv6 Non-Forwarding Hash Table:
+ Hash table ip6 FIB non-fwding table
+ 131079 active elements 32773 active buckets
+ 2 free lists
+ [len 1] 2 free elts
+ 0 linear search buckets
+ arena: base 7fed7a514000, next 4805c0
+ used 4720064 b (4 Mbytes) of 1073741824 b (1024 Mbytes)
+
+ IPv6 Forwarding Hash Table:
+ Hash table ip6 FIB fwding table
+ 131079 active elements 32773 active buckets
+ 2 free lists
+ [len 1] 2 free elts
+ 0 linear search buckets
+ arena: base 7fedba514000, next 4805c0
+ used 4720064 b (4 Mbytes) of 1073741824 b (1024 Mbytes)
+
+and 256k:
+
+.. code-block:: console
+
+ vpp# sh ip6 fib mem
+ IPv6 Non-Forwarding Hash Table:
+ Hash table ip6 FIB non-fwding table
+ 262151 active elements 65536 active buckets
+ 2 free lists
+ [len 1] 6 free elts
+ 0 linear search buckets
+ arena: base 7fed7a514000, next 880840
+ used 8915008 b (8 Mbytes) of 1073741824 b (1024 Mbytes)
+
+ IPv6 Forwarding Hash Table:
+ Hash table ip6 FIB fwding table
+ 262151 active elements 65536 active buckets
+ 2 free lists
+ [len 1] 6 free elts
+ 0 linear search buckets
+ arena: base 7fedba514000, next 880840
+ used 8915008 b (8 Mbytes) of 1073741824 b (1024 Mbytes)
+
+and 1M:
+
+.. code-block:: console
+
+ vpp# sh ip6 fib mem
+ IPv6 Non-Forwarding Hash Table:
+ Hash table ip6 FIB non-fwding table
+ 1048583 active elements 65536 active buckets
+ 4 free lists
+ [len 1] 65533 free elts
+ [len 2] 65531 free elts
+ [len 4] 9 free elts
+ 0 linear search buckets
+ arena: base 7fed7a514000, next 3882740
+ used 59254592 b (56 Mbytes) of 1073741824 b (1024 Mbytes)
+
+ IPv6 Forwarding Hash Table:
+ Hash table ip6 FIB fwding table
+ 1048583 active elements 65536 active buckets
+ 4 free lists
+ [len 1] 65533 free elts
+ [len 2] 65531 free elts
+ [len 4] 9 free elts
+ 0 linear search buckets
+ arena: base 7fedba514000, next 3882740
+ used 59254592 b (56 Mbytes) of 1073741824 b (1024 Mbytes)
+
+as can be seen from the output the IPv6 heap in this case was scaled
+to 1GB and 1million prefixes has used 56MB of it.
+
+
+Main Heap
+---------
+
+The main heap is used to allocate objects that represent the FIB
+entries in the control and data plane (see :ref:`controlplane` and
+:ref:`dataplane`) such as *fib_entry_t* and *load_balance_t*. These come
+from the main heap because they are not protocol specific
+(i.e. they are used to represent either IPv4, IPv6 or MPLS
+entries).
+
+With 1M prefixes allocated the memory usage is:
+
+.. code-block:: console
+
+ vpp# sh fib mem
+ FIB memory
+ Tables:
+ SAFI Number Bytes
+ IPv4 unicast 1 33619968
+ IPv6 unicast 2 118502784
+ MPLS 0 0
+ IPv4 multicast 1 1175
+ IPv6 multicast 1 525312
+ Nodes:
+ Name Size in-use /allocated totals
+ Entry 72 1048589/ 1048589 75498408/75498408
+ Entry Source 40 1048589/ 1048589 41943560/41943560
+ Entry Path-Extensions 76 0 / 0 0/0
+ multicast-Entry 192 6 / 6 1152/1152
+ Path-list 40 18 / 18 720/720
+ uRPF-list 16 14 / 14 224/224
+ Path 72 22 / 22 1584/1584
+ Node-list elements 20 1048602/ 1048602 20972040/20972040
+ Node-list heads 8 24 / 24 192/192
+
+and with 2M
+
+.. code-block:: console
+
+ vpp# sh fib mem
+ FIB memory
+ Tables:
+ SAFI Number Bytes
+ IPv4 unicast 1 33619968
+ IPv6 unicast 2 252743040
+ MPLS 0 0
+ IPv4 multicast 1 1175
+ IPv6 multicast 1 525312
+ Nodes:
+ Name Size in-use /allocated totals
+ Entry 72 2097165/ 2097165 150995880/150995880
+ Entry Source 40 2097165/ 2097165 83886600/83886600
+ Entry Path-Extensions 76 0 / 0 0/0
+ multicast-Entry 192 6 / 6 1152/1152
+ Path-list 40 18 / 19 720/760
+ uRPF-list 16 18 / 18 288/288
+ Path 72 22 / 23 1584/1656
+ Node-list elements 20 2097178/ 2097178 41943560/41943560
+ Node-list heads 8 24 / 24 192/192
+
+However, the situation is not a simple as that. All of the 1M prefixes
+added above were reachable via the same next-hop, so the path-list
+(and path) they use is shared. As prefixes are added that use
+different (sets of) next-hops, the number of path-lists and paths
+requires will increase.
+
+
+Stats Heap
+----------
+
+VPP collects statistics for each route. For each route VPP collects
+byte and packet counters for packets sent to the prefix (i.e. the
+route was matched in the data-plane) and packets sent via the prefix (i.e. the
+matching prefix is reachable through it - like a BGP peer). This
+requires 4 counters per route in the stats segment.
+
+Below shows the size of the stats segment with 1M, 2M and 4M routes.
+
+.. code-block:: console
+
+ total: 1023.99M, used: 127.89M, free: 896.10M, trimmable: 830.94M
+ total: 1023.99M, used: 234.14M, free: 789.85M, trimmable: 668.15M
+ total: 1023.99M, used: 456.83M, free: 567.17M, trimmable: 388.91M
+
+VPP was started with a 1G stats heap.
+