Re: [PATCH v5] gro : packets not getting flushed in heavy-weight mode API

[Ferruh Yigit <ferruh.yigit@amd.com>]

On 1/18/2024 8:36 AM, Kumara Parameshwaran wrote:
> In heavy-weight mode GRO which is based on timer, the GRO packets
> will not be flushed in spite of timer expiry if there is no packet
> in the current poll. If timer mode GRO is enabled the
> rte_gro_timeout_flush API should be invoked.
> 

Agree on the problem, need a way to flush existing packets in GRO
context when no more packet receiving.


> Signed-off-by: Kumara Parameshwaran <kumaraparamesh92@gmail.com>
> ---
> v1:
>     Changes to make sure that the GRO flush API is invoked if there are no packets in 
>     current poll and timer expiry.
> 
> v2:
>     Fix code organisation issue
> 
> v3:
>     Fix warnings
> 
> v4:
>     Fix error and warnings
> 
> v5:
>     Fix compilation issue when GRO is not defined
> 
>  app/test-pmd/csumonly.c | 15 +++++++++++----
>  1 file changed, 11 insertions(+), 4 deletions(-)
> 
> diff --git a/app/test-pmd/csumonly.c b/app/test-pmd/csumonly.c
> index c103e54111..6d9ce99500 100644
> --- a/app/test-pmd/csumonly.c
> +++ b/app/test-pmd/csumonly.c
> @@ -863,16 +863,23 @@ pkt_burst_checksum_forward(struct fwd_stream *fs)
>  
>  	/* receive a burst of packet */
>  	nb_rx = common_fwd_stream_receive(fs, pkts_burst, nb_pkt_per_burst);
> +#ifndef RTE_LIB_GRO
>  	if (unlikely(nb_rx == 0))
>  		return false;
> -
> +#else
> +	gro_enable = gro_ports[fs->rx_port].enable;
> +	if (unlikely(nb_rx == 0)) {
> +		if (gro_enable && (gro_flush_cycles != GRO_DEFAULT_FLUSH_CYCLES))
> +			goto init;
>

Rest of the function expects 'nb_rx' non zero, so I am concerned about
unexpected side effects, like:

- GRO reassembles packets and flush, how reassembles behaves with zero
nb_rx?

- If there is no packet in GRO context, what happens to call with zero
nb_rx?


To address above issue, what about add 'rte_gro_get_pkt_count()' check
and only continue if it return not zero.
Also in below GRO block, call 'rte_gro_reassemble()' only when 'nb_rx'
is not zero.

> +		else
> +			return false;
>

'goto' can be prevented by changing the condition in if block.


> +	}
> +init:
>

Label name 'init' is not a good name.

> +#endif
>  	rx_bad_ip_csum = 0;
>  	rx_bad_l4_csum = 0;
>  	rx_bad_outer_l4_csum = 0;
>  	rx_bad_outer_ip_csum = 0;
> -#ifdef RTE_LIB_GRO
> -	gro_enable = gro_ports[fs->rx_port].enable;
> -#endif
>  
>  	txp = &ports[fs->tx_port];
>  	tx_offloads = txp->dev_conf.txmode.offloads;