RE: [PATCH v7 1/1] baseband/acc100: add detection for deRM corner cases

["Chautru, Nicolas" <nicolas.chautru@intel.com>]

Given how close we are to 22.11, let's not argue over this. Hernan sending a new patch based on Maxime recommendation. 

> -----Original Message-----
> From: Chautru, Nicolas
> Sent: Thursday, November 3, 2022 9:21 AM
> To: Maxime Coquelin <maxime.coquelin@redhat.com>; Vargas, Hernan
> <Hernan.Vargas@intel.com>; dev@dpdk.org; gakhil@marvell.com;
> trix@redhat.com
> Cc: Zhang, Qi Z <qi.z.zhang@intel.com>
> Subject: RE: [PATCH v7 1/1] baseband/acc100: add detection for deRM corner
> cases
> 
> Hi Maxime, Akhil,
> 
> 
> > -----Original Message-----
> > From: Maxime Coquelin <maxime.coquelin@redhat.com>
> > Sent: Thursday, November 3, 2022 8:08 AM
> > To: Chautru, Nicolas <nicolas.chautru@intel.com>; Vargas, Hernan
> > <hernan.vargas@intel.com>; dev@dpdk.org; gakhil@marvell.com;
> > trix@redhat.com
> > Cc: Zhang, Qi Z <qi.z.zhang@intel.com>
> > Subject: Re: [PATCH v7 1/1] baseband/acc100: add detection for deRM
> > corner cases
> >
> > Hi Nicolas,
> >
> > On 11/3/22 15:59, Chautru, Nicolas wrote:
> > > Hi Maxime,
> > >
> > >> -----Original Message-----
> > >> From: Maxime Coquelin <maxime.coquelin@redhat.com>
> > >> Sent: Thursday, November 3, 2022 7:10 AM
> > >> To: Vargas, Hernan <hernan.vargas@intel.com>; dev@dpdk.org;
> > >> gakhil@marvell.com; trix@redhat.com
> > >> Cc: Chautru, Nicolas <nicolas.chautru@intel.com>; Zhang, Qi Z
> > >> <qi.z.zhang@intel.com>
> > >> Subject: Re: [PATCH v7 1/1] baseband/acc100: add detection for deRM
> > >> corner cases
> > >>
> > >>
> > >>
> > >> On 11/1/22 05:13, Hernan Vargas wrote:
> > >>> Add function to detect if de-ratematch pre-processing is
> > >>> recommended for SW corner cases.
> > >>> Some specific 5GUL FEC corner cases may cause unintended back
> > >>> pressure and in some cases a potential stability issue on the ACC100.
> > >>> The PMD can detect such code block configuration and issue an info
> > >>> message to the user.
> > >>>
> > >>> Signed-off-by: Hernan Vargas <hernan.vargas@intel.com>
> > >>> ---
> > >>>    drivers/baseband/acc/acc_common.h     |  8 ++++
> > >>>    drivers/baseband/acc/rte_acc100_pmd.c | 55
> > >> +++++++++++++++++++++++++--
> > >>>    2 files changed, 60 insertions(+), 3 deletions(-)
> > >>>
> > >>> diff --git a/drivers/baseband/acc/acc_common.h
> > >>> b/drivers/baseband/acc/acc_common.h
> > >>> index eae7eab4e9..6213b0b61e 100644
> > >>> --- a/drivers/baseband/acc/acc_common.h
> > >>> +++ b/drivers/baseband/acc/acc_common.h
> > >>> @@ -123,6 +123,14 @@
> > >>>    #define ACC_HARQ_ALIGN_64B          64
> > >>>    #define ACC_MAX_ZC                  384
> > >>>
> > >>> +/* De-ratematch code rate limitation for recommended operation */
> > >>> +#define ACC_LIM_03 2  /* 0.03 */ #define ACC_LIM_09 6  /* 0.09 */
> > >>> +#define ACC_LIM_14 9  /* 0.14 */ #define ACC_LIM_21 14 /* 0.21 */
> > >>> +#define ACC_LIM_31 20 /* 0.31 */ #define ACC_MAX_E (128 * 1024 -
> > >>> +2)
> > >>> +
> > >>>    /* Helper macro for logging */
> > >>>    #define rte_acc_log(level, fmt, ...) \
> > >>>    	rte_log(RTE_LOG_ ## level, RTE_LOG_NOTICE, fmt "\n", \ diff
> > >>> --git a/drivers/baseband/acc/rte_acc100_pmd.c
> > >>> b/drivers/baseband/acc/rte_acc100_pmd.c
> > >>> index 23bc5d25bb..47609f95b7 100644
> > >>> --- a/drivers/baseband/acc/rte_acc100_pmd.c
> > >>> +++ b/drivers/baseband/acc/rte_acc100_pmd.c
> > >>> @@ -756,6 +756,14 @@ acc100_queue_setup(struct rte_bbdev *dev,
> > >> uint16_t queue_id,
> > >>>    		ret = -ENOMEM;
> > >>>    		goto free_lb_out;
> > >>>    	}
> > >>> +	q->derm_buffer = rte_zmalloc_socket(dev->device->driver->name,
> > >>> +			RTE_BBDEV_TURBO_MAX_CB_SIZE * 10,
> > >>> +			RTE_CACHE_LINE_SIZE, conf->socket);
> > >>> +	if (q->derm_buffer == NULL) {
> > >>> +		rte_bbdev_log(ERR, "Failed to allocate derm_buffer
> memory");
> > >>> +		ret = -ENOMEM;
> > >>> +		goto free_companion_ring_addr;
> > >>> +	}
> > >>>
> > >>>    	/*
> > >>>    	 * Software queue ring wraps synchronously with the HW when it
> > >>> reaches @@ -776,7 +784,7 @@ acc100_queue_setup(struct rte_bbdev
> > >>> *dev,
> > >> uint16_t queue_id,
> > >>>    	q_idx = acc100_find_free_queue_idx(dev, conf);
> > >>>    	if (q_idx == -1) {
> > >>>    		ret = -EINVAL;
> > >>> -		goto free_companion_ring_addr;
> > >>> +		goto free_derm_buffer;
> > >>>    	}
> > >>>
> > >>>    	q->qgrp_id = (q_idx >> ACC100_GRP_ID_SHIFT) & 0xF; @@ -804,6
> > >> +812,9
> > >>> @@ acc100_queue_setup(struct rte_bbdev *dev, uint16_t queue_id,
> > >>>    	dev->data->queues[queue_id].queue_private = q;
> > >>>    	return 0;
> > >>>
> > >>> +free_derm_buffer:
> > >>> +	rte_free(q->derm_buffer);
> > >>> +	q->derm_buffer = NULL;
> > >>>    free_companion_ring_addr:
> > >>>    	rte_free(q->companion_ring_addr);
> > >>>    	q->companion_ring_addr = NULL; @@ -890,6 +901,7 @@
> > >>> acc100_queue_release(struct rte_bbdev *dev,
> > >> uint16_t q_id)
> > >>>    		/* Mark the Queue as un-assigned */
> > >>>    		d->q_assigned_bit_map[q->qgrp_id] &= (0xFFFFFFFFFFFFFFFF -
> > >>>    				(uint64_t) (1 << q->aq_id));
> > >>> +		rte_free(q->derm_buffer);
> > >>>    		rte_free(q->companion_ring_addr);
> > >>>    		rte_free(q->lb_in);
> > >>>    		rte_free(q->lb_out);
> > >>> @@ -3111,10 +3123,41 @@ harq_loopback(struct acc_queue *q, struct
> > >> rte_bbdev_dec_op *op,
> > >>>    	return 1;
> > >>>    }
> > >>>
> > >>> +/* Assess whether a work around is recommended for the deRM
> > >>> +corner cases */ static inline bool
> > >>> +derm_workaround_recommended(struct
> > >>> +rte_bbdev_op_ldpc_dec *ldpc_dec, struct acc_queue *q) {
> > >>> +	if (!is_acc100(q))
> > >>> +		return false;
> > >>> +	int32_t e = ldpc_dec->cb_params.e;
> > >>> +	int q_m = ldpc_dec->q_m;
> > >>> +	int z_c = ldpc_dec->z_c;
> > >>> +	int K = (ldpc_dec->basegraph == 1 ? ACC_K_ZC_1 : ACC_K_ZC_2) * z_c;
> > >>> +	bool recommended = false;
> > >>> +
> > >>> +	if (ldpc_dec->basegraph == 1) {
> > >>> +		if ((q_m == 4) && (z_c >= 320) && (e * ACC_LIM_31 > K * 64))
> > >>> +			recommended = true;
> > >>> +		else if ((e * ACC_LIM_21 > K * 64))
> > >>> +			recommended = true;
> > >>> +	} else {
> > >>> +		if (q_m <= 2) {
> > >>> +			if ((z_c >= 208) && (e * ACC_LIM_09 > K * 64))
> > >>> +				recommended = true;
> > >>> +			else if ((z_c < 208) && (e * ACC_LIM_03 > K * 64))
> > >>> +				recommended = true;
> > >>> +		} else if (e * ACC_LIM_14 > K * 64)
> > >>> +			recommended = true;
> > >>> +	}
> > >>> +
> > >>> +	return recommended;
> > >>> +}
> > >>> +
> > >>>    /** Enqueue one decode operations for ACC100 device in CB mode */
> > >>>    static inline int
> > >>>    enqueue_ldpc_dec_one_op_cb(struct acc_queue *q, struct
> > >> rte_bbdev_dec_op *op,
> > >>> -		uint16_t total_enqueued_cbs, bool same_op)
> > >>> +		uint16_t total_enqueued_cbs, bool same_op,
> > >>> +		struct rte_bbdev_queue_data *q_data)
> > >>>    {
> > >>>    	int ret;
> > >>>    	if (unlikely(check_bit(op->ldpc_dec.op_flags,
> > >>> @@ -3168,6 +3211,12 @@ enqueue_ldpc_dec_one_op_cb(struct
> > acc_queue
> > >> *q, struct rte_bbdev_dec_op *op,
> > >>>    	} else {
> > >>>    		struct acc_fcw_ld *fcw;
> > >>>    		uint32_t seg_total_left;
> > >>> +
> > >>> +		if (derm_workaround_recommended(&op->ldpc_dec, q)) {
> > >>> +			RTE_SET_USED(q_data);
> > >> Why do we need q_data if it is not being used?
> > >
> > > As you can guess this notably allows customer do consider running
> > > deRM
> > from here as a local patch hence keeping the q_data accessible.
> > > Basically we keep the prototype of the function
> > enqueue_ldpc_dec_one_op_cb() compatible with such usage.
> > > I believe this is a good practice here. Let us know if you are not convinced.
> >
> > I think it is better to just warn the user, without adding unused parameters.
> 
> Thanks Maxime.
> Akhil, any additional view on this? For the PMD usage and support this makes
> more sense to keep to prototype with q_data even with RTE_SET_USED().
> I don't see any meaningful drawback justifying to push back. Still let us know.
> 
> Thanks
> Nic
>