Note: If this would exceed the maximum number of filters, an error message is output, and the filter is
not inserted. For example:
rmgr: Cannot find appropriate slot to insert rule
Cannot insert classification rule
2. Optionally list the rules for the interface and confirm that the new rule is present:
# ethtool -n <interface>
For example:
# ethtool -n enp1s0f0np0
8 RX rings available
Total 1 rules
Filter: 0
Rule Type: UDP over IPv4
Src IP addr: 0.0.0.0 mask: 255.255.255.255
Dest IP addr: 192.168.10.200 mask: 0.0.0.0
TOS: 0x0 mask: 0xff
Src port: 0 mask: 0xffff
Dest port: 1234 mask: 0x0
Action: Direct to queue 3
3. Use the taskset command to start your application on its desired CPU:
taskset -c <cpu> <command line>
4. Have your application create a filter with the same parameters as the ethtool rule.
The pre-installed ethtool rule is recognized as identical and is re-used. The application
therefore uses the receive queue that was specified for the ethtool rule.
5. When your application quits, delete the ethtool rule:
ethtool -N <interface> delete <rule number>
For example, to delete rule 0 that was installed in step above:
ethtool -N enp1s0f0np0 delete 0
6. List the rules for the interface and confirm that the rule is deleted:
# ethtool -n <interface>
For example:
# ethtool -n enp1s0f0np0
8 RX rings available
Total 0 rules
Note: The use of taskset is typically only suitable for affinity tuning single threaded, single traffic flow
applications. For a multi-threaded application, whose threads for example process a subset of receive
traffic, taskset is not suitable. In such applications, you might use multiple ethtool rules to spread receive
traffic over multiple queues and then have each application thread bind to an adjacent CPU. Thread
affinities can be set inside the application with the
shed_setaffinity()
function (see Linux man
pages). Use of this call and how a particular application can be tuned is beyond the scope of this guide.
Chapter 5: Tuning
UG1523 (v1.0) October 18, 2022
Alveo X3522 User Guide
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