From: Ophir Munk <ophirmu@mellanox.com>
To: dev@dpdk.org, Pascal Mazon <pascal.mazon@6wind.com>
Cc: Thomas Monjalon <thomas@monjalon.net>,
Olga Shern <olgas@mellanox.com>,
Ophir Munk <ophirmu@mellanox.com>
Subject: [dpdk-dev] [PATCH v5 6/6] doc: detail new tap RSS feature in guides
Date: Thu, 18 Jan 2018 13:38:11 +0000 [thread overview]
Message-ID: <1516282691-29698-7-git-send-email-ophirmu@mellanox.com> (raw)
In-Reply-To: <1516282691-29698-1-git-send-email-ophirmu@mellanox.com>
Signed-off-by: Ophir Munk <ophirmu@mellanox.com>
---
doc/guides/nics/tap.rst | 60 +++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 60 insertions(+)
diff --git a/doc/guides/nics/tap.rst b/doc/guides/nics/tap.rst
index 04086b1..dc6f834 100644
--- a/doc/guides/nics/tap.rst
+++ b/doc/guides/nics/tap.rst
@@ -132,6 +132,7 @@ Supported actions:
- DROP
- QUEUE
- PASSTHRU
+- RSS
It is generally not possible to provide a "last" item. However, if the "last"
item, once masked, is identical to the masked spec, then it is supported.
@@ -161,6 +162,11 @@ Drop UDP packets in vlan 3::
testpmd> flow create 0 priority 3 ingress pattern eth / vlan vid is 3 / \
ipv4 proto is 17 / end actions drop / end
+Distribute IPv4 TCP packets using RSS to a given MAC address over queues 0-3::
+
+ testpmd> flow create 0 priority 4 ingress pattern eth dst is 0a:0b:0c:0d:0e:0f \
+ / ipv4 / tcp / end actions rss queues 0 1 2 3 end / end
+
Example
-------
@@ -213,3 +219,57 @@ traffic is being looped back. You can use ``set all size XXX`` to change the
size of the packets after you stop the traffic. Use pktgen ``help``
command to see a list of all commands. You can also use the ``-f`` option to
load commands at startup in command line or Lua script in pktgen.
+
+RSS specifics
+-------------
+Packet distribution in TAP is done by the kernel which has a default
+distribution. This feature is adding RSS distribution based on eBPF code.
+The default eBPF code calculates RSS hash based on Toeplitz algorithm for
+a fixed RSS key. It is calculated on fixed packet offsets. For IPv4 and IPv6 it
+is calculated over src/dst addresses (8 or 32 bytes for IPv4 or IPv6
+respectively) and src/dst TCP/UDP ports (4 bytes).
+
+The RSS algorithm is written in file ``tap_bpf_program.c`` which
+does not take part in TAP PMD compilation. Instead this file is compiled
+in advance to eBPF object file. The eBPF object file is then parsed and
+translated into eBPF byte code in the format of C arrays of eBPF
+instructions. The C array of eBPF instructions is part of TAP PMD tree and
+is taking part in TAP PMD compilation. At run time the C arrays are uploaded to
+the kernel via BPF system calls and the RSS hash is calculated by the
+kernel.
+
+It is possible to support different RSS hash algorithms by updating file
+``tap_bpf_program.c`` In order to add a new RSS hash algorithm follow these
+steps:
+
+1. Write the new RSS implementation in file ``tap_bpf_program.c``
+
+BPF programs which are uploaded to the kernel correspond to
+C functions under different ELF sections.
+
+2. Install ``LLVM`` library and ``clang`` compiler versions 3.7 and above
+
+3. Compile ``tap_bpf_program.c`` via ``LLVM`` into an object file::
+
+ clang -O2 -emit-llvm -c tap_bpf_program.c -o - | llc -march=bpf \
+ -filetype=obj -o <tap_bpf_program.o>
+
+
+4. Use a tool that receives two parameters: an eBPF object file and a section
+name, and prints out the section as a C array of eBPF instructions.
+Embed the C array in your TAP PMD tree.
+
+The C arrays are uploaded to the kernel using BPF system calls.
+
+``tc`` (traffic control) is a well known user space utility program used to
+configure the Linux kernel packet scheduler. It is usually packaged as
+part of the ``iproute2`` package.
+Since commit 11c39b5e9 ("tc: add eBPF support to f_bpf") ``tc`` can be used
+to uploads eBPF code to the kernel and can be patched in order to print the
+C arrays of eBPF instructions just before calling the BPF system call.
+Please refer to ``iproute2`` package file ``lib/bpf.c`` function
+``bpf_prog_load()``.
+
+An example utility for eBPF instruction generation in the format of C arrays will
+be added in next releases
+
--
2.7.4
next prev parent reply other threads:[~2018-01-18 13:38 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-17 12:21 [dpdk-dev] [PATCH v1 0/3] TAP RSS eBPF cover letter Ophir Munk
2017-12-17 12:21 ` [dpdk-dev] [PATCH v1 1/3] net/tap: add BPF sections for TAP device Ophir Munk
2017-12-17 12:21 ` [dpdk-dev] [PATCH v1 2/3] net/tap: add eBPF instructions Ophir Munk
2017-12-17 12:21 ` [dpdk-dev] [PATCH v1 3/3] net/tap: add eBPF classifiers map and actions Ophir Munk
2017-12-28 10:09 ` [dpdk-dev] [PATCH v2 0/2] TAP RSS eBPF cover letter Ophir Munk
2017-12-28 10:09 ` [dpdk-dev] [PATCH v2 1/2] net/tap: add eBPF instructions to TAP device Ophir Munk
2017-12-28 10:09 ` [dpdk-dev] [PATCH v2 2/2] net/tap: implement RSS with eBPF classifier and action Ophir Munk
2018-01-10 7:06 ` [dpdk-dev] [PATCH v3 0/2] TAP RSS eBPF cover letter Ophir Munk
2018-01-10 7:06 ` [dpdk-dev] [PATCH v3 1/2] net/tap: add eBPF instructions to TAP device Ophir Munk
2018-01-10 9:34 ` Pascal Mazon
2018-01-10 10:12 ` Ophir Munk
2018-01-10 7:06 ` [dpdk-dev] [PATCH v3 2/2] net/tap: implement RSS with eBPF classifier and action Ophir Munk
2018-01-10 10:19 ` Pascal Mazon
2018-01-11 17:20 ` Ophir Munk
2018-01-10 10:10 ` [dpdk-dev] [PATCH v3 0/2] TAP RSS eBPF cover letter Jason Wang
2018-01-10 15:34 ` Ophir Munk
2018-01-11 2:45 ` Jason Wang
2018-01-11 17:45 ` [dpdk-dev] [PATCH v4 0/5] " Ophir Munk
2018-01-11 17:45 ` [dpdk-dev] [PATCH v4 1/5] net/tap: support actions for different classifiers Ophir Munk
2018-01-11 17:45 ` [dpdk-dev] [PATCH v4 2/5] net/tap: add eBPF bytes code Ophir Munk
2018-01-11 17:45 ` [dpdk-dev] [PATCH v4 3/5] net/tap: add eBPF program file Ophir Munk
2018-01-11 17:45 ` [dpdk-dev] [PATCH v4 4/5] net/tap: add eBPF API Ophir Munk
2018-01-11 17:45 ` [dpdk-dev] [PATCH v4 5/5] net/tap: implement TAP RSS using eBPF Ophir Munk
2018-01-18 13:38 ` [dpdk-dev] [PATCH v5 0/6] TAP RSS eBPF cover letter Ophir Munk
2018-01-18 13:38 ` [dpdk-dev] [PATCH v5 1/6] net/tap: support actions for different classifiers Ophir Munk
2018-01-18 13:38 ` [dpdk-dev] [PATCH v5 2/6] net/tap: add eBPF bytes code Ophir Munk
2018-01-18 13:38 ` [dpdk-dev] [PATCH v5 3/6] net/tap: add eBPF program file Ophir Munk
2018-01-18 13:38 ` [dpdk-dev] [PATCH v5 4/6] net/tap: add eBPF API Ophir Munk
2018-01-18 13:38 ` [dpdk-dev] [PATCH v5 5/6] net/tap: implement TAP RSS using eBPF Ophir Munk
2018-01-18 13:38 ` Ophir Munk [this message]
2018-01-19 6:48 ` [dpdk-dev] [PATCH v5 0/6] TAP RSS eBPF cover letter Pascal Mazon
2018-01-20 16:15 ` Ferruh Yigit
2018-01-20 21:25 ` Ophir Munk
2018-01-21 14:20 ` Ferruh Yigit
2018-01-20 21:11 ` [dpdk-dev] [PATCH v6 " Ophir Munk
2018-01-20 21:11 ` [dpdk-dev] [PATCH v6 1/6] net/tap: support actions for different classifiers Ophir Munk
2018-01-20 21:11 ` [dpdk-dev] [PATCH v6 2/6] net/tap: add eBPF program file Ophir Munk
2018-01-20 21:11 ` [dpdk-dev] [PATCH v6 3/6] net/tap: add eBPF bytes code Ophir Munk
2018-01-20 21:11 ` [dpdk-dev] [PATCH v6 4/6] net/tap: add eBPF API Ophir Munk
2018-01-20 21:11 ` [dpdk-dev] [PATCH v6 5/6] net/tap: implement TAP RSS using eBPF Ophir Munk
2018-01-20 21:11 ` [dpdk-dev] [PATCH v6 6/6] doc: detail new tap RSS feature in guides Ophir Munk
2018-01-21 14:50 ` [dpdk-dev] [PATCH v6 0/6] TAP RSS eBPF cover letter Ferruh Yigit
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1516282691-29698-7-git-send-email-ophirmu@mellanox.com \
--to=ophirmu@mellanox.com \
--cc=dev@dpdk.org \
--cc=olgas@mellanox.com \
--cc=pascal.mazon@6wind.com \
--cc=thomas@monjalon.net \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).