Re: [PATCH v2 10/37] baseband/acc100: avoid mux for small inbound frames

[Maxime Coquelin <maxime.coquelin@redhat.com>]

On 8/20/22 04:31, Hernan Vargas wrote:
> Update check_mux to avoid multiplexing small inbound frames.
> Preventing to multiplex code blocks when K < 512B per specs.

It looks like a fix, and so should Fixes tag be added an stable cc'ed.

> Signed-off-by: Hernan Vargas <hernan.vargas@intel.com>
> ---
>   drivers/baseband/acc100/acc100_pmd.h     |  1 +
>   drivers/baseband/acc100/rte_acc100_pmd.c | 16 +++++++++++-----
>   2 files changed, 12 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/baseband/acc100/acc100_pmd.h b/drivers/baseband/acc100/acc100_pmd.h
> index 0c9810ca56..19a1f434bc 100644
> --- a/drivers/baseband/acc100/acc100_pmd.h
> +++ b/drivers/baseband/acc100/acc100_pmd.h
> @@ -135,6 +135,7 @@
>   #define ACC100_DEC_OFFSET     (80)
>   #define ACC100_EXT_MEM /* Default option with memory external to CPU */
>   #define ACC100_HARQ_OFFSET_THRESHOLD 1024
> +#define ACC100_LIMIT_DL_MUX_BITS 534
>   
>   /* Constants from K0 computation from 3GPP 38.212 Table 5.4.2.1-2 */
>   #define ACC100_N_ZC_1 66 /* N = 66 Zc for BG 1 */
> diff --git a/drivers/baseband/acc100/rte_acc100_pmd.c b/drivers/baseband/acc100/rte_acc100_pmd.c
> index 5d09908fd0..71409e11a1 100644
> --- a/drivers/baseband/acc100/rte_acc100_pmd.c
> +++ b/drivers/baseband/acc100/rte_acc100_pmd.c
> @@ -3548,20 +3548,25 @@ acc100_enqueue_enc_cb(struct rte_bbdev_queue_data *q_data,
>   }
>   
>   /* Check we can mux encode operations with common FCW */
> -static inline bool
> +static inline int16_t
>   check_mux(struct rte_bbdev_enc_op **ops, uint16_t num) {
>   	uint16_t i;
>   	if (num <= 1)
> -		return false;
> +		return 1;
>   	for (i = 1; i < num; ++i) {
>   		/* Only mux compatible code blocks */
>   		if (memcmp((uint8_t *)(&ops[i]->ldpc_enc) + ACC100_ENC_OFFSET,
>   				(uint8_t *)(&ops[0]->ldpc_enc) +
>   				ACC100_ENC_OFFSET,
>   				ACC100_CMP_ENC_SIZE) != 0)
> -			return false;
> +			return i;
>   	}
> -	return true;
> +	/* Avoid multiplexing small inbound size frames */
> +	int Kp = (ops[0]->ldpc_enc.basegraph == 1 ? 22 : 10) *
> +			ops[0]->ldpc_enc.z_c - ops[0]->ldpc_enc.n_filler;
> +	if (Kp  <= ACC100_LIMIT_DL_MUX_BITS)
> +		return 1;
> +	return num;
>   }
>   
>   /** Enqueue encode operations for ACC100 device in CB mode. */
> @@ -3583,7 +3588,8 @@ acc100_enqueue_ldpc_enc_cb(struct rte_bbdev_queue_data *q_data,
>   		}
>   		avail--;
>   		enq = RTE_MIN(left, ACC100_MUX_5GDL_DESC);
> -		if (check_mux(&ops[i], enq)) {
> +		enq = check_mux(&ops[i], enq);
> +		if (enq > 1) {
>   			ret = enqueue_ldpc_enc_n_op_cb(q, &ops[i],
>   					desc_idx, enq);
>   			if (ret < 0) {