Hi Maxime,
> -----Original Message-----
> From: Maxime Coquelin <maxime.coque...@redhat.com>
> Sent: Tuesday, October 25, 2022 1:26 AM
> To: Vargas, Hernan <hernan.var...@intel.com>; dev@dpdk.org;
> gak...@marvell.com; t...@redhat.com
> Cc: Chautru, Nicolas <nicolas.chau...@intel.com>; Zhang, Qi Z
> <qi.z.zh...@intel.com>; David Marchand <david.march...@redhat.com>;
> Thomas Monjalon <tho...@monjalon.net>
> Subject: Re: [PATCH v6 1/1] baseband/acc100: add workaround for deRM
> corner cases
>
> Hi Hernan,
>
> On 10/25/22 04:38, Hernan Vargas wrote:
> > Add function to support de-ratematch pre-processing 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.
> > To be able to avoid completely such potential issue, the PMD can
> > preempt such code block configuration so that to process the first
> > level deRM in SW using the SDK libraries prior to running the rest of
> > the FEC decoding in HW using an amended code block configuration.
> > In case meson build system doesn't find such SDK libraries, the fall
> > method is to run in HW with a warning.
> >
> > Signed-off-by: Hernan Vargas <hernan.var...@intel.com>
> > ---
> > drivers/baseband/acc/acc_common.h | 8 ++
> > drivers/baseband/acc/meson.build | 21 +++++
> > drivers/baseband/acc/rte_acc100_pmd.c | 108
> +++++++++++++++++++++++++-
> > 3 files changed, 134 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/baseband/acc/acc_common.h
> > b/drivers/baseband/acc/acc_common.h
> > index eae7eab4e9..5e8972b40a 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 when padding is required */
> > +#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/meson.build b/drivers/baseband/acc/meson.build
> > index 77c393b533..a5fc4fed01 100644
> > --- a/drivers/baseband/acc/meson.build
> > +++ b/drivers/baseband/acc/meson.build
> > @@ -1,6 +1,27 @@
> > # SPDX-License-Identifier: BSD-3-Clause
> > # Copyright(c) 2020 Intel Corporation
> >
> > +# Check for FlexRAN SDK libraries
> > +dep_dec5g = dependency('flexran_sdk_ldpc_decoder_5gnr', required:
> > +false)
> > +
> > +if dep_dec5g.found()
> > + ext_deps += cc.find_library('libstdc++', required: true)
> > + ext_deps += cc.find_library('libirc', required: true)
> > + ext_deps += cc.find_library('libimf', required: true)
> > + ext_deps += cc.find_library('libipps', required: true)
> > + ext_deps += cc.find_library('libsvml', required: true)
> > + ext_deps += dep_dec5g
> > + ext_deps += dependency('flexran_sdk_ldpc_encoder_5gnr', required:
> true)
> > + ext_deps += dependency('flexran_sdk_LDPC_ratematch_5gnr', required:
> true)
> > + ext_deps += dependency('flexran_sdk_rate_dematching_5gnr', required:
> true)
> > + ext_deps += dependency('flexran_sdk_turbo', required: true)
> > + ext_deps += dependency('flexran_sdk_crc', required: true)
> > + ext_deps += dependency('flexran_sdk_rate_matching', required: true)
> > + ext_deps += dependency('flexran_sdk_common', required: true)
> > + cflags += ['-DRTE_BBDEV_SDK_AVX2']
> > + cflags += ['-DRTE_BBDEV_SDK_AVX512'] endif
> > +
> > deps += ['bbdev', 'bus_pci']
> >
> > sources = files('rte_acc100_pmd.c', 'rte_acc200_pmd.c') diff --git
> > a/drivers/baseband/acc/rte_acc100_pmd.c
> > b/drivers/baseband/acc/rte_acc100_pmd.c
> > index 23bc5d25bb..e8b230e563 100644
> > --- a/drivers/baseband/acc/rte_acc100_pmd.c
> > +++ b/drivers/baseband/acc/rte_acc100_pmd.c
> > @@ -25,6 +25,10 @@
> > #include "acc101_pmd.h"
> > #include "acc200_cfg.h"
> >
> > +#ifdef RTE_BBDEV_SDK_AVX512
> > +#include <phy_rate_dematching_5gnr.h> #endif
> > +
> > #ifdef RTE_LIBRTE_BBDEV_DEBUG
> > RTE_LOG_REGISTER_DEFAULT(acc100_logtype, DEBUG);
> > #else
> > @@ -756,6 +760,14 @@ 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 +788,7 @@ 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
> +816,9
> > @@ 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 +905,7 @@ 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 +3127,44 @@ harq_loopback(struct acc_queue *q, struct
> rte_bbdev_dec_op *op,
> > return 1;
> > }
> >
> > +/** Assess whether a work around is required for the deRM corner
> > +cases */ static inline bool derm_workaround_required(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 required = false;
> > + if (ldpc_dec->basegraph == 1) {
> > + if ((q_m == 4) && (z_c >= 320) && (e * ACC_LIM_31 > K * 64))
> > + required = true;
> > + else if ((e * ACC_LIM_21 > K * 64))
> > + required = true;
> > + } else {
> > + if (q_m <= 2) {
> > + if ((z_c >= 208) && (e * ACC_LIM_09 > K * 64))
> > + required = true;
> > + else if ((z_c < 208) && (e * ACC_LIM_03 > K * 64))
> > + required = true;
> > + } else if (e * ACC_LIM_14 > K * 64)
> > + required = true;
> > + }
> > + if (required)
> > + rte_bbdev_log(INFO, "Running deRM pre-processing in SW");
> > +
> > + return required;
> > +}
> > +
> > /** 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 +3218,58 @@ 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_required(&op->ldpc_dec, q)) {
> > + #ifdef RTE_BBDEV_SDK_AVX512
> > + struct rte_bbdev_op_ldpc_dec *dec = &op->ldpc_dec;
> > + struct bblib_rate_dematching_5gnr_request
> derm_req;
> > + struct bblib_rate_dematching_5gnr_response
> derm_resp;
> > + uint8_t *in;
> > +
> > + /* Checking input size is matching with E */
> > + if (dec->input.data->data_len < dec->cb_params.e) {
> > + rte_bbdev_log(ERR, "deRM: Input size
> mismatch");
> > + return -EFAULT;
> > + }
> > + /* Run first deRM processing in SW */
> > + in = rte_pktmbuf_mtod_offset(dec->input.data, uint8_t
> *, in_offset);
> > + derm_req.p_in = (int8_t *) in;
> > + derm_req.p_harq = (int8_t *) q->derm_buffer;
> > + derm_req.base_graph = dec->basegraph;
> > + derm_req.zc = dec->z_c;
> > + derm_req.ncb = dec->n_cb;
> > + derm_req.e = dec->cb_params.e;
> > + if (derm_req.e > ACC_MAX_E) {
> > + rte_bbdev_log(WARNING,
> > + "deRM: E %d > %d max",
> > + derm_req.e, ACC_MAX_E);
> > + derm_req.e = ACC_MAX_E;
> > + }
> > + derm_req.k0 = 0; /* Actual output from SDK */
> > + derm_req.isretx = false;
> > + derm_req.rvid = dec->rv_index;
> > + derm_req.modulation_order = dec->q_m;
> > + derm_req.start_null_index =
> > + (dec->basegraph == 1 ? 22 : 10)
> > + * dec->z_c - 2 * dec->z_c
> > + - dec->n_filler;
> > + derm_req.num_of_null = dec->n_filler;
> > + bblib_rate_dematching_5gnr(&derm_req,
> &derm_resp);
> > + /* Force back the HW DeRM */
> > + dec->q_m = 1;
> > + dec->cb_params.e = dec->n_cb - dec->n_filler;
> > + dec->rv_index = 0;
> > + rte_memcpy(in, q->derm_buffer, dec->cb_params.e);
> > + /* Capture counter when pre-processing is used */
> > + q_data->queue_stats.enqueue_warn_count++;
> > + #else
> > + RTE_SET_USED(q_data);
> > + rte_bbdev_log(WARNING,
> > + "Corner case may require deRM pre-
> processing in SDK"
> > + );
> > + #endif
> > + }
> > +
> > fcw = &desc->req.fcw_ld;
> > q->d->fcw_ld_fill(op, fcw, harq_layout);
> >
> > @@ -3721,7 +3823,7 @@ acc100_enqueue_ldpc_dec_cb(struct
> rte_bbdev_queue_data *q_data,
> > ops[i]->ldpc_dec.n_cb, ops[i]->ldpc_dec.q_m,
> > ops[i]->ldpc_dec.n_filler, ops[i]-
> >ldpc_dec.cb_params.e,
> > same_op);
> > - ret = enqueue_ldpc_dec_one_op_cb(q, ops[i], i, same_op);
> > + ret = enqueue_ldpc_dec_one_op_cb(q, ops[i], i, same_op,
> q_data);
> > if (ret < 0) {
> > acc_enqueue_invalid(q_data);
> > break;
>
> As I already replied on a previous revision, I think it is not acceptable to
> condition the fix on forcing to depend on a proprietary SDK. The ACC100 driver
> did not have this Flexran SDK requirement initially, not like the SW-only
> BBDEV
> PMDs.
The SDK is not proprietary. This is available on IDZ with a permissible license
and includes a plain C code implementation in case there is no AVX512 isa on
the CPU.
> In my opinion, you can keep the call to Flexran SDK API but you should provide
> an open-source alternative, even if not optimized so that it is at least
> functionnal. Later contributors could provide an optimized open-source version
> if they feel the need.
Again the SDK is available on the IDZ with a permissible license and includes a
plain C implementation.
> I had a quick look at the bblib_rate_dematching_5gnr C implementation, and it
> is reasonably small and there is really nothing special in it.
>
> Not having an open-source alternative is problematic, because it could make CI
> to fail when using test-bbdev application if the HW bug is triggered.
CI would not fail.
We can discuss further offline later this week as there seems to be some
confusion still.
Thanks
Nic
>
> Regards,
> Maxime
