mlx5-updates-2019-09-01 (Software steering support)
Abstract:
--------
Mellanox ConnetX devices supports packet matching, packet modification and
redirection. These functionalities are also referred to as flow-steering.
To configure a steering rule, the rule is written to the device owned
memory, this memory is accessed and cached by the device when processing
a packet.
Steering rules are constructed from multiple steering entries (STE).
Rules are configured using the Firmware command interface. The Firmware
processes the given driver command and translates them to STEs, then
writes them to the device memory in the current steering tables.
This process is slow due to the architecture of the command interface and
the processing complexity of each rule.
The highlight of this patchset is to cut the middle man (The firmware) and
do steering rules programming into device directly from the driver, with
no firmware intervention whatsoever.
Motivation:
-----------
Software (driver managed) steering allows for high rule insertion rates
compared to the FW steering described above, this is achieved by using
internal RDMA writes to the device owned memory instead of the slow
command interface to program steering rules.
Software (driver managed) steering, doesn't depend on new FW
for new steering functionality, new implementations can be done in the
driver skipping the FW layer.
Performance:
------------
The insertion rate on a single core using the new approach allows
programming ~300K rules per sec. (Done via direct raw test to the new mlx5
sw steering layer, without any kernel layer involved).
Test: TC L2 rules
33K/s with Software steering (this patchset).
5K/s with FW and current driver.
This will improve OVS based solution performance.
Architecture and implementation details:
----------------------------------------
Software steering will be dynamically selected via devlink device
parameter. Example:
$ devlink dev param show pci/0000:06:00.0 name flow_steering_mode
pci/0000:06:00.0:
name flow_steering_mode type driver-specific
values:
cmode runtime value smfs
mlx5 software steering module a.k.a (DR - Direct Rule) is implemented
and contained in mlx5/core/steering directory and controlled by
MLX5_SW_STEERING kconfig flag.
mlx5 core steering layer (fs_core) already provides a shim layer for
implementing different steering mechanisms, software steering will
leverage that as seen at the end of this series.
When Software Steering for a specific steering domain
(NIC/RDMA/Vport/ESwitch, etc ..) is supported, it will cause rules
targeting this domain to be created using SW steering instead of FW.
The implementation includes:
Domain - The steering domain is the object that all other object resides
in. It holds the memory allocator, send engine, locks and other shared
data needed by lower objects such as table, matcher, rule, action.
Each domain can contain multiple tables. Domain is equivalent to
namespaces e.g (NIC/RDMA/Vport/ESwitch, etc ..) as implemented
currently in mlx5_core fs_core (flow steering core).
Table - Table objects are used for holding multiple matchers, each table
has a level used to prevent processing loops. Packets are being
directed to this table once it is set as the root table, this is done
by fs_core using a FW command. A packet is being processed inside the
table matcher by matcher until a successful hit, otherwise the packet
will perform the default action.
Matcher - Matchers objects are used to specify the fields mask for
matching when processing a packet. A matcher belongs to a table, each
matcher can hold multiple rules, each rule with different matching
values corresponding to the matcher mask. Each matcher has a priority
used for rule processing order inside the table.
Action - Action objects are created to specify different steering actions
such as count, reformat (encapsulate, decapsulate, ...), modify
header, forward to table and many other actions. When creating a rule
a sequence of actions can be provided to be executed on a successful
match.
Rule - Rule objects are used to specify a specific match on packets as
well as the actions that should be executed. A rule belongs to a
matcher.
STE - This layer is used to hold the specific STE format for the device
and to convert the requested rule to STEs. Each rule is constructed of
an STE chain, Multiple rules construct a steering graph. Each node in
the graph is a hash table containing multiple STEs. The index of each
STE in the hash table is being calculated using a CRC32 hash function.
Memory pool - Used for managing and caching device owned memory for rule
insertion. The memory is being allocated using DM (device memory) API.
Communication with device - layer for standard RDMA operation using RC QP
to configure the device steering.
Command utility - This module holds all of the FW commands that are
required for SW steering to function.
Patch planning and files:
-------------------------
1) First patch, adds the support to Add flow steering actions to fs_cmd
shim layer.
2) Next 12 patch will add a file per each Software steering
functionality/module as described above. (See patches with title: DR, *)
3) Add CONFIG_MLX5_SW_STEERING for software steering support and enable
build with the new files
4) Next two patches will add the support for software steering in mlx5
steering shim layer
net/mlx5: Add API to set the namespace steering mode
net/mlx5: Add direct rule fs_cmd implementation
5) Last two patches will add the new devlink parameter to select mlx5
steering mode, will be valid only for switchdev mode for now.
Two modes are supported:
1. DMFS - Device managed flow steering
2. SMFS - Software/Driver managed flow steering.
In the DMFS mode, the HW steering entities are created through the
FW. In the SMFS mode this entities are created though the driver
directly.
The driver will use the devlink steering mode only if the steering
domain supports it, for now SMFS will manages only the switchdev
eswitch steering domain.
User command examples:
- Set SMFS flow steering mode::
$ devlink dev param set pci/0000:06:00.0 name flow_steering_mode value "smfs" cmode runtime
- Read device flow steering mode::
$ devlink dev param show pci/0000:06:00.0 name flow_steering_mode
pci/0000:06:00.0:
name flow_steering_mode type driver-specific
values:
cmode runtime value smfs
net/mlx5: Add devlink flow_steering_mode parameter
Add new parameter (flow_steering_mode) to control the flow steering
mode of the driver.
Two modes are supported:
1. DMFS - Device managed flow steering
2. SMFS - Software/Driver managed flow steering.
In the DMFS mode, the HW steering entities are created through the
FW. In the SMFS mode this entities are created though the driver
directly.
The driver will use the devlink steering mode only if the steering
domain supports it, for now SMFS will manages only the switchdev eswitch
steering domain.
User command examples:
- Set SMFS flow steering mode::
$ devlink dev param set pci/0000:06:00.0 name flow_steering_mode value "smfs" cmode runtime
- Read device flow steering mode::
$ devlink dev param show pci/0000:06:00.0 name flow_steering_mode
pci/0000:06:00.0:
name flow_steering_mode type driver-specific
values:
cmode runtime value smfs
Signed-off-by: Maor Gottlieb <maorg@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
2 files changed
