On 8 Sep 2025, at 17:26, Kevin Traynor via dev wrote:
> Add some more details about dpdk-lcore-mask and remove
> the recommendation to use it.
>
> Signed-off-by: Kevin Traynor <ktray...@redhat.com>
> ---
> vswitchd/vswitch.xml | 17 ++++++++++++-----
> 1 file changed, 12 insertions(+), 5 deletions(-)
>
> diff --git a/vswitchd/vswitch.xml b/vswitchd/vswitch.xml
> index 332d8890d..25b0989ac 100644
> --- a/vswitchd/vswitch.xml
> +++ b/vswitchd/vswitch.xml
> @@ -335,11 +335,18 @@
> </p>
> <p>
> - For performance reasons, it is best to set this to a single core on
> - the system, rather than allow lcore threads to float.
> + The lowest set core will be assigned in DPDK as the DPDK main
> thread.
> + Other set bits will be assigned by DPDK as DPDK worker threads.
> + As OVS implements it's own threading for the datapath (see
> + <ref column="other_config" key="pmd-cpu-mask"/>), DPDK worker
> + threads will be unused.
> </p>
> <p>
> - If not specified, the value will be determined by choosing the
> lowest
> - CPU core from initial cpu affinity list. Otherwise, the value will
> be
> - passed directly to the DPDK library.
> + If this option is specified, OVS main/handler/revalidator threads
> + will run on the selected DPDK main thread core.
Should it be a bit clearer that they will all run on a single core, and this
might not be desired?
Maybe something along the lines of:
If this option is specified, all OVS main, handler, and revalidator threads
will be pinned to the selected DPDK main thread core. This means that
potentially many threads will share a single CPU core, which may not be
desirable for performance reasons.
> + </p>
> + <p>
> + If this option is not specified the value for DPDK initialization
> + will be auto-determined and OVS main/revalidator/handler threads
> will
> + float on the OVS cpu affinity list.
> </p>
> </column>
> --
> 2.51.0
>
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