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Stefano Brivio 4051f43116 nft_set_pipapo: Add support for 8-bit lookup groups and dynamic switch
While grouping matching bits in groups of four saves memory compared
to the more natural choice of 8-bit words (lookup table size is one
eighth), it comes at a performance cost, as the number of lookup
comparisons is doubled, and those also needs bitshifts and masking.

Introduce support for 8-bit lookup groups, together with a mapping
mechanism to dynamically switch, based on defined per-table size
thresholds and hysteresis, between 8-bit and 4-bit groups, as tables
grow and shrink. Empty sets start with 8-bit groups, and per-field
tables are converted to 4-bit groups if they get too big.

An alternative approach would have been to swap per-set lookup
operation functions as needed, but this doesn't allow for different
group sizes in the same set, which looks desirable if some fields
need significantly more matching data compared to others due to
heavier impact of ranges (e.g. a big number of subnets with
relatively simple port specifications).

Allowing different group sizes for the same lookup functions implies
the need for further conditional clauses, whose cost, however,
appears to be negligible in tests.

The matching rate figures below were obtained for x86_64 running
the nft_concat_range.sh "performance" cases, averaged over five
runs, on a single thread of an AMD Epyc 7402 CPU, and for aarch64
on a single thread of a BCM2711 (Raspberry Pi 4 Model B 4GB),
clocked at a stable 2147MHz frequency:

---------------.-----------------------------------.------------.
AMD Epyc 7402  |          baselines, Mpps          | this patch |
 1 thread      |___________________________________|____________|
 3.35GHz       |        |        |        |        |            |
 768KiB L1D$   | netdev |  hash  | rbtree |        |            |
---------------|  hook  |   no   | single | pipapo |   pipapo   |
type   entries |  drop  | ranges | field  | 4 bits | bit switch |
---------------|--------|--------|--------|--------|------------|
net,port       |        |        |        |        |            |
         1000  |   19.0 |   10.4 |    3.8 |    2.8 | 4.0   +43% |
---------------|--------|--------|--------|--------|------------|
port,net       |        |        |        |        |            |
          100  |   18.8 |   10.3 |    5.8 |    5.5 | 6.3   +14% |
---------------|--------|--------|--------|--------|------------|
net6,port      |        |        |        |        |            |
         1000  |   16.4 |    7.6 |    1.8 |    1.3 | 2.1   +61% |
---------------|--------|--------|--------|--------|------------|
port,proto     |        |        |        |        |     [1]    |
        30000  |   19.6 |   11.6 |    3.9 |    0.3 | 0.5   +66% |
---------------|--------|--------|--------|--------|------------|
net6,port,mac  |        |        |        |        |            |
           10  |   16.5 |    5.4 |    4.3 |    2.6 | 3.4   +31% |
---------------|--------|--------|--------|--------|------------|
net6,port,mac, |        |        |        |        |            |
proto    1000  |   16.5 |    5.7 |    1.9 |    1.0 | 1.4   +40% |
---------------|--------|--------|--------|--------|------------|
net,mac        |        |        |        |        |            |
         1000  |   19.0 |    8.4 |    3.9 |    1.7 | 2.5   +47% |
---------------'--------'--------'--------'--------'------------'
[1] Causes switch of lookup table buckets for 'port', not 'proto',
    to 4-bit groups

 ---------------.-----------------------------------.------------.
 BCM2711        |          baselines, Mpps          | this patch |
  1 thread      |___________________________________|____________|
  2147MHz       |        |        |        |        |            |
  32KiB L1D$    | netdev |  hash  | rbtree |        |            |
 ---------------|  hook  |   no   | single | pipapo |   pipapo   |
 type   entries |  drop  | ranges | field  | 4 bits | bit switch |
 ---------------|--------|--------|--------|--------|------------|
 net,port       |        |        |        |        |            |
          1000  |   1.63 |   1.37 |   0.87 |   0.61 | 0.70  +17% |
 ---------------|--------|--------|--------|--------|------------|
 port,net       |        |        |        |        |            |
           100  |   1.64 |   1.36 |   1.02 |   0.78 | 0.81   +4% |
 ---------------|--------|--------|--------|--------|------------|
 net6,port      |        |        |        |        |            |
          1000  |   1.56 |   1.27 |   0.65 |   0.34 | 0.50  +47% |
 ---------------|--------|--------|--------|--------|------------|
 port,proto [2] |        |        |        |        |            |
         10000  |   1.68 |   1.43 |   0.84 |   0.30 | 0.40  +13% |
 ---------------|--------|--------|--------|--------|------------|
 net6,port,mac  |        |        |        |        |            |
            10  |   1.56 |   1.14 |   1.02 |   0.62 | 0.66   +6% |
 ---------------|--------|--------|--------|--------|------------|
 net6,port,mac, |        |        |        |        |            |
 proto    1000  |   1.56 |   1.12 |   0.64 |   0.27 | 0.40  +48% |
 ---------------|--------|--------|--------|--------|------------|
 net,mac        |        |        |        |        |            |
          1000  |   1.63 |   1.26 |   0.87 |   0.41 | 0.53  +29% |
 ---------------'--------'--------'--------'--------'------------'
[2] Using 10000 entries instead of 30000 as it would take way too
    long for the test script to generate all of them

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2020-03-15 15:27:43 +01:00
arch Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2020-03-13 20:52:03 -07:00
block block, bfq: fix overwrite of bfq_group pointer in bfq_find_set_group() 2020-03-06 07:00:58 -07:00
certs certs: Add wrapper function to check blacklisted binary hash 2019-11-12 12:25:50 +11:00
crypto Merge branch 'next-integrity' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity 2020-02-20 15:15:16 -08:00
Documentation Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2020-03-13 20:52:03 -07:00
drivers cdc_ncm: Fix the build warning 2020-03-15 00:41:29 -07:00
fs Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2020-03-13 20:52:03 -07:00
include netfilter: flowtable: add tunnel match offload support 2020-03-15 15:26:17 +01:00
init Tracing updates: 2020-02-26 10:34:42 -08:00
ipc Revert "ipc,sem: remove uneeded sem_undo_list lock usage in exit_sem()" 2020-02-21 11:22:15 -08:00
kernel Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2020-03-13 20:52:03 -07:00
lib Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2020-02-29 15:53:35 -08:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
mm Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2020-03-12 16:19:19 -07:00
net nft_set_pipapo: Add support for 8-bit lookup groups and dynamic switch 2020-03-15 15:27:43 +01:00
samples Kbuild updates for v5.6 (2nd) 2020-02-09 16:05:50 -08:00
scripts Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2020-03-13 20:52:03 -07:00
security Merge branch 'next-integrity' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity 2020-02-20 15:15:16 -08:00
sound Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2020-03-12 22:34:48 -07:00
tools selftests: mlxsw: RED: Test RED ECN nodrop offload 2020-03-14 21:03:46 -07:00
usr Kbuild updates for v5.6 (2nd) 2020-02-09 16:05:50 -08:00
virt KVM/arm fixes for 5.6, take #1 2020-02-28 11:50:06 +01:00
.clang-format clang-format: Update with the latest for_each macro list 2020-03-06 21:50:05 +01:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore selftest/lkdtm: Use local .gitignore 2020-03-02 08:39:39 -07:00
.mailmap A handful of small documentation fixes that wandered in. 2020-02-07 13:03:10 -08:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Hand MIPS over to Thomas 2020-02-24 22:43:18 -08:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig docs: kbuild: convert docs to ReST and rename to *.rst 2019-06-14 14:21:21 -06:00
MAINTAINERS Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2020-03-13 20:52:03 -07:00
Makefile Linux 5.6-rc5 2020-03-08 17:44:44 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.