[ovs-dev] [PATCH v3] flow: Read recirc depth and flow api enabled once per batch in miniflow_extract

Eli Britstein elibr at nvidia.com
Tue Jun 29 05:35:22 UTC 2021


On 6/28/2021 6:19 PM, Balazs Nemeth wrote:
> External email: Use caution opening links or attachments
>
>
> The call to recirc_depth_get involves accessing a TLS value. So read
> that once, and store it on the stack for re-use while processing the
> batch. The same goes for reading netdev_is_flow_api_enabled(), a
> non-inlined function.

A small further suggestion:

The config other_config:hw-offload is read only once upon init, so for 
netdev_is_flow_api_enabled(), we can have a global static variable to be 
set only at init (dpif_netdev_set_config) by the non-inline function.

Then, we can replace all other calls with this variable.

Other than that, LGTM.

>
> Signed-off-by: Balazs Nemeth <bnemeth at redhat.com>
> Acked-by: Gaetan Rivet <grive at u256.net>
> Acked-by: Paolo Valerio <pvalerio at redhat.com>
> ---
>   lib/dpif-netdev.c | 4 +++-
>   1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/lib/dpif-netdev.c b/lib/dpif-netdev.c
> index c5ab35d2a..bf2112ead 100644
> --- a/lib/dpif-netdev.c
> +++ b/lib/dpif-netdev.c
> @@ -7165,6 +7165,8 @@ dfc_processing(struct dp_netdev_pmd_thread *pmd,
>       struct dp_packet *packet;
>       const size_t cnt = dp_packet_batch_size(packets_);
>       uint32_t cur_min = pmd->ctx.emc_insert_min;
> +    const uint32_t recirc_depth = *recirc_depth_get();
> +    const bool netdev_flow_api = netdev_is_flow_api_enabled();
>       int i;
>       uint16_t tcp_flags;
>       bool smc_enable_db;
> @@ -7196,7 +7198,7 @@ dfc_processing(struct dp_netdev_pmd_thread *pmd,
>               pkt_metadata_init(&packet->md, port_no);
>           }
>
> -        if (netdev_is_flow_api_enabled() && *recirc_depth_get() == 0) {
> +        if (netdev_flow_api && recirc_depth == 0) {
>               if (OVS_UNLIKELY(dp_netdev_hw_flow(pmd, port_no, packet, &flow))) {
>                   /* Packet restoration failed and it was dropped, do not
>                    * continue processing.
> --
> 2.31.1
>


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