Re: [PATCH net-next v4 6/8] gve: Add rx hardware timestamp expansion

[Vadim Fedorenko]

On 09/06/2025 19:40, Harshitha Ramamurthy wrote:
> From: John Fraker <jfraker@xxxxxxxxxx>
>
> Allow the rx path to recover the high 32 bits of the full 64 bit rx
> timestamp.
>
> Use the low 32 bits of the last synced nic time and the 32 bits of the
> timestamp provided in the rx descriptor to generate a difference, which
> is then applied to the last synced nic time to reconstruct the complete
> 64-bit timestamp.
>
> This scheme remains accurate as long as no more than ~2 seconds have
> passed between the last read of the nic clock and the timestamping
> application of the received packet.
>
> Signed-off-by: John Fraker <jfraker@xxxxxxxxxx>
> Signed-off-by: Ziwei Xiao <ziweixiao@xxxxxxxxxx>
> Reviewed-by: Willem de Bruijn <willemb@xxxxxxxxxx>
> Signed-off-by: Harshitha Ramamurthy <hramamurthy@xxxxxxxxxx>
> ---
>   Changes in v3:
>   - Change the last_read to be u64 (Vadim Fedorenko)
>
>   Changes in v2:
>   - Add the missing READ_ONCE (Joe Damato)
> ---

Reviewed-by: Vadim Fedorenko <vadim.fedorenko@xxxxxxxxx>