From a18ed9d92d0b06e468c173a948a6dfa6d6d08f65 Mon Sep 17 00:00:00 2001
From: Robert Schmidt <robert.schmidt@eurecom.fr>
Date: Mon, 14 Dec 2020 15:44:52 +0100
Subject: [PATCH] Reorder DLSCH MAC PDU logic
Before this commit, the DLSCH scheduler would construct the MAC PDU by
reading RLC data into a memory on the stack, and then construct the PDU
with CEs first. There are at least two problems:
- we need to keep track of the exact number of bytes of CEs (cumbersome)
to calculate the number of MAC SDUs to include
- we needlessly copy data around.
This commit does the following instead:
- write all CEs first (no need of keeping track of this in DLSCH and a
separate function)
- then read MAC SDUs directly into nFAPI as much as possible or
necessary, without recopying
---
.../LAYER2/NR_MAC_gNB/gNB_scheduler_dlsch.c | 234 +++++++-----------
openair2/LAYER2/NR_MAC_gNB/mac_proto.h | 11 -
2 files changed, 89 insertions(+), 156 deletions(-)
diff --git a/openair2/LAYER2/NR_MAC_gNB/gNB_scheduler_dlsch.c b/openair2/LAYER2/NR_MAC_gNB/gNB_scheduler_dlsch.c
index ea7eabdded3..a7c37b83f9e 100644
--- a/openair2/LAYER2/NR_MAC_gNB/gNB_scheduler_dlsch.c
+++ b/openair2/LAYER2/NR_MAC_gNB/gNB_scheduler_dlsch.c
@@ -56,27 +56,22 @@
#define WORD 32
//#define SIZE_OF_POINTER sizeof (void *)
-int nr_generate_dlsch_pdu(module_id_t module_idP,
- NR_UE_sched_ctrl_t *ue_sched_ctl,
- unsigned char *sdus_payload,
+// Compute and write all MAC CEs and subheaders, and return number of written
+// bytes
+int nr_write_ce_dlsch_pdu(module_id_t module_idP,
+ const NR_UE_sched_ctrl_t *ue_sched_ctl,
unsigned char *mac_pdu,
- unsigned char num_sdus,
- unsigned short *sdu_lengths,
- unsigned char *sdu_lcids,
unsigned char drx_cmd,
- unsigned char *ue_cont_res_id,
- unsigned short post_padding) {
+ unsigned char *ue_cont_res_id)
+{
gNB_MAC_INST *gNB = RC.nrmac[module_idP];
NR_MAC_SUBHEADER_FIXED *mac_pdu_ptr = (NR_MAC_SUBHEADER_FIXED *) mac_pdu;
- unsigned char *dlsch_buffer_ptr = sdus_payload;
uint8_t last_size = 0;
int offset = 0, mac_ce_size, i, timing_advance_cmd, tag_id = 0;
// MAC CEs
uint8_t mac_header_control_elements[16], *ce_ptr;
ce_ptr = &mac_header_control_elements[0];
- // 1) Compute MAC CE and related subheaders
-
// DRX command subheader (MAC CE size 0)
if (drx_cmd != 255) {
mac_pdu_ptr->R = 0;
@@ -301,42 +296,6 @@ int nr_generate_dlsch_pdu(module_id_t module_idP,
}
}
- // 2) Generation of DLSCH MAC subPDUs including subheaders and MAC SDUs
- for (i = 0; i < num_sdus; i++) {
-
- if (sdu_lengths[i] < 256) {
- ((NR_MAC_SUBHEADER_SHORT *) mac_pdu_ptr)->R = 0;
- ((NR_MAC_SUBHEADER_SHORT *) mac_pdu_ptr)->F = 0;
- ((NR_MAC_SUBHEADER_SHORT *) mac_pdu_ptr)->LCID = sdu_lcids[i];
- ((NR_MAC_SUBHEADER_SHORT *) mac_pdu_ptr)->L = (unsigned char) sdu_lengths[i];
- last_size = 2;
- } else {
- ((NR_MAC_SUBHEADER_LONG *) mac_pdu_ptr)->R = 0;
- ((NR_MAC_SUBHEADER_LONG *) mac_pdu_ptr)->F = 1;
- ((NR_MAC_SUBHEADER_LONG *) mac_pdu_ptr)->LCID = sdu_lcids[i];
- ((NR_MAC_SUBHEADER_LONG *) mac_pdu_ptr)->L1 = ((unsigned short) sdu_lengths[i] >> 8) & 0xff;
- ((NR_MAC_SUBHEADER_LONG *) mac_pdu_ptr)->L2 = (unsigned short) sdu_lengths[i] & 0xff;
- last_size = 3;
- }
-
- mac_pdu_ptr += last_size;
- // 3) cycle through SDUs, compute each relevant and place dlsch_buffer in
- memcpy((void *) mac_pdu_ptr, (void *) dlsch_buffer_ptr, sdu_lengths[i]);
- dlsch_buffer_ptr += sdu_lengths[i];
- mac_pdu_ptr += sdu_lengths[i];
- LOG_D(MAC, "Generate DLSCH header num sdu %d len header %d len sdu %d -> offset %ld\n", num_sdus, last_size, sdu_lengths[i], (unsigned char *)mac_pdu_ptr - mac_pdu);
- }
-
- // 4) Compute final offset for padding
- if (post_padding > 0) {
- ((NR_MAC_SUBHEADER_FIXED *) mac_pdu_ptr)->R = 0;
- ((NR_MAC_SUBHEADER_FIXED *) mac_pdu_ptr)->LCID = DL_SCH_LCID_PADDING;
- mac_pdu_ptr++;
- LOG_D(MAC, "Generate Padding -> offset %ld\n", (unsigned char *)mac_pdu_ptr - mac_pdu);
- } else {
- // no MAC subPDU with padding
- }
-
// compute final offset
offset = ((unsigned char *) mac_pdu_ptr - mac_pdu);
//printf("Offset %d \n", ((unsigned char *) mac_pdu_ptr - mac_pdu));
@@ -593,7 +552,7 @@ void nr_schedule_ue_spec(module_id_t module_id,
const int nrOfLayers = 1;
const uint16_t R = nr_get_code_rate_dl(sched_ctrl->mcs, sched_ctrl->mcsTableIdx);
const uint8_t Qm = nr_get_Qm_dl(sched_ctrl->mcs, sched_ctrl->mcsTableIdx);
- const uint32_t TBS =
+ uint32_t TBS =
nr_compute_tbs(nr_get_Qm_dl(sched_ctrl->mcs, sched_ctrl->mcsTableIdx),
nr_get_code_rate_dl(sched_ctrl->mcs, sched_ctrl->mcsTableIdx),
sched_ctrl->rbSize,
@@ -842,108 +801,105 @@ void nr_schedule_ue_spec(module_id_t module_id,
} else { /* initial transmission */
LOG_D(MAC, "[%s] Initial HARQ transmission in %d.%d\n", __FUNCTION__, frame, slot);
- /* reserve space for timing advance of UE if necessary,
- * nr_generate_dlsch_pdu() checks for ta_apply and add TA CE if necessary */
- const int ta_len = (sched_ctrl->ta_apply) ? 2 : 0;
-
- /* Get RLC data */
- int header_length_total = 0;
- int header_length_last = 0;
- int sdu_length_total = 0;
- int num_sdus = 0;
- uint16_t sdu_lengths[NB_RB_MAX] = {0};
- uint8_t mac_sdus[MAX_NR_DLSCH_PAYLOAD_BYTES];
- unsigned char sdu_lcids[NB_RB_MAX] = {0};
+ const int ntx_req = gNB_mac->TX_req[CC_id].Number_of_PDUs;
+ nfapi_nr_pdu_t *tx_req = &gNB_mac->TX_req[CC_id].pdu_list[ntx_req];
+ tx_req->PDU_length = TBS;
+ tx_req->PDU_index = pduindex;
+ tx_req->num_TLV = 1;
+ tx_req->TLVs[0].length = TBS + 2;
+ /* pointer to directly generate the PDU into the nFAPI structure */
+ uint8_t *buf = (uint8_t *) tx_req->TLVs[0].value.direct;
+ gNB_mac->TX_req[CC_id].Number_of_PDUs++;
+ gNB_mac->TX_req[CC_id].SFN = frame;
+ gNB_mac->TX_req[CC_id].Slot = slot;
+
+ /* first, write all CEs that might be there */
+ int written = nr_write_ce_dlsch_pdu(module_id,
+ sched_ctrl,
+ (unsigned char *)buf,
+ 255, // no drx
+ NULL); // contention res id
+ buf += written;
+ TBS -= written;
+
+ DevAssert(TBS > 3);
+
+ /* next, get RLC data */
+ // we do not know how much data we will get from RLC, i.e., whether it
+ // will be longer than 256B or not. Therefore, reserve space for long header, then
+ // fetch data, then fill real length
+ NR_MAC_SUBHEADER_LONG *header = (NR_MAC_SUBHEADER_LONG *) buf;
+ buf += 3;
+ TBS -= 3;
+
const int lcid = DL_SCH_LCID_DTCH;
+ int dlsch_total_bytes = 0;
if (sched_ctrl->num_total_bytes > 0) {
/* this is the data from the RLC we would like to request (e.g., only
* some bytes for first LC and some more from a second one */
- const rlc_buffer_occupancy_t ndata = sched_ctrl->rlc_status[lcid].bytes_in_buffer;
- /* this is the maximum data we can transport based on TBS minus headers */
- const int mindata = min(ndata, TBS - ta_len - header_length_total - sdu_length_total - 2 - (ndata >= 256));
+ const rlc_buffer_occupancy_t ndata = min(sched_ctrl->rlc_status[lcid].bytes_in_buffer, TBS);
+ const tbs_size_t len = mac_rlc_data_req(module_id,
+ rnti,
+ module_id,
+ frame,
+ ENB_FLAG_YES,
+ MBMS_FLAG_NO,
+ lcid,
+ ndata,
+ (char *)buf,
+ 0,
+ 0);
+
LOG_D(MAC,
- "[gNB %d][USER-PLANE DEFAULT DRB] Frame %d : DTCH->DLSCH, Requesting "
- "%d bytes from RLC (lcid %d total hdr len %d), TBS: %d \n \n",
- module_id,
+ "%4d.%2d RNTI %04x: %d bytes from DTCH %d (ndata %d, rem TBS %d)\n",
frame,
- mindata,
+ slot,
+ rnti,
+ len,
lcid,
- header_length_total,
+ ndata,
TBS);
- sdu_lengths[num_sdus] = mac_rlc_data_req(module_id,
- rnti,
- module_id,
- frame,
- ENB_FLAG_YES,
- MBMS_FLAG_NO,
- lcid,
- mindata,
- (char *)&mac_sdus[sdu_length_total],
- 0,
- 0);
-
- LOG_D(MAC,
- "[gNB %d][USER-PLANE DEFAULT DRB] Got %d bytes for DTCH %d \n",
- module_id,
- sdu_lengths[num_sdus],
- lcid);
-
- sdu_lcids[num_sdus] = lcid;
- sdu_length_total += sdu_lengths[num_sdus];
- header_length_last = 1 + 1 + (sdu_lengths[num_sdus] >= 128);
- header_length_total += header_length_last;
- num_sdus++;
+ header->R = 0;
+ header->F = 1;
+ header->LCID = lcid;
+ header->L1 = (len >> 8) & 0xff;
+ header->L2 = len & 0xff;
+ TBS -= len;
+ buf += len;
+ dlsch_total_bytes += len;
}
else if (get_softmodem_params()->phy_test || get_softmodem_params()->do_ra) {
- LOG_D(MAC, "Configuring DL_TX in %d.%d: random data\n", frame, slot);
+ LOG_D(MAC, "Configuring DL_TX in %d.%d: TBS %d B of random data\n", frame, slot, TBS);
// fill dlsch_buffer with random data
for (int i = 0; i < TBS; i++)
- mac_sdus[i] = (unsigned char) (lrand48()&0xff);
- sdu_lcids[0] = 0x3f; // DRB
- sdu_lengths[0] = TBS - ta_len - 3;
- header_length_total += 2 + (sdu_lengths[0] >= 256);
- sdu_length_total += sdu_lengths[0];
- num_sdus +=1;
+ buf[i] = lrand48() & 0xff;
+ header->R = 0;
+ header->F = 1;
+ header->LCID = DL_SCH_LCID_PADDING;
+ header->L1 = (TBS >> 8) & 0xff;
+ header->L2 = TBS & 0xff;
+ TBS -= TBS;
+ buf += TBS;
+ dlsch_total_bytes += TBS;
}
- UE_info->mac_stats[UE_id].dlsch_total_bytes += TBS;
- UE_info->mac_stats[UE_id].lc_bytes_tx[lcid] += sdu_length_total;
-
- const int post_padding = TBS > header_length_total + sdu_length_total + ta_len;
-
- const int ntx_req = gNB_mac->TX_req[CC_id].Number_of_PDUs;
- nfapi_nr_pdu_t *tx_req = &gNB_mac->TX_req[CC_id].pdu_list[ntx_req];
- /* pointer to directly generate the PDU into the nFAPI structure */
- uint32_t *buf = tx_req->TLVs[0].value.direct;
-
- const int offset = nr_generate_dlsch_pdu(
- module_id,
- sched_ctrl,
- (unsigned char *)mac_sdus,
- (unsigned char *)buf,
- num_sdus, // num_sdus
- sdu_lengths,
- sdu_lcids,
- 255, // no drx
- NULL, // contention res id
- post_padding);
-
- // Padding: fill remainder of DLSCH with 0
- if (post_padding > 0) {
- for (int j = 0; j < TBS - offset; j++)
- buf[offset + j] = 0;
+ // Add padding header and zero rest out if there is space left
+ if (TBS > 0) {
+ NR_MAC_SUBHEADER_FIXED *padding = (NR_MAC_SUBHEADER_FIXED *) buf;
+ padding->R = 0;
+ padding->LCID = DL_SCH_LCID_PADDING;
+ TBS -= 1;
+ buf += 1;
+ while (TBS > 0) {
+ *buf = 0;
+ buf += 1;
+ TBS -= 1;
+ }
}
- /* the buffer has been filled by nr_generate_dlsch_pdu(), below we simply
- * fill the remaining information */
- tx_req->PDU_length = TBS;
- tx_req->PDU_index = pduindex;
- tx_req->num_TLV = 1;
- tx_req->TLVs[0].length = TBS + 2;
- gNB_mac->TX_req[CC_id].Number_of_PDUs++;
- gNB_mac->TX_req[CC_id].SFN = frame;
- gNB_mac->TX_req[CC_id].Slot = slot;
+ UE_info->mac_stats[UE_id].dlsch_total_bytes += dlsch_total_bytes;
+ UE_info->mac_stats[UE_id].lc_bytes_tx[lcid] += dlsch_total_bytes;
retInfo->rbSize = sched_ctrl->rbSize;
retInfo->time_domain_allocation = sched_ctrl->time_domain_allocation;
@@ -964,18 +920,6 @@ void nr_schedule_ue_spec(module_id_t module_id,
T(T_GNB_MAC_DL_PDU_WITH_DATA, T_INT(module_id), T_INT(CC_id), T_INT(rnti),
T_INT(frame), T_INT(slot), T_INT(current_harq_pid), T_BUFFER(buf, TBS));
-
-#if defined(ENABLE_MAC_PAYLOAD_DEBUG)
- if (frame%100 == 0) {
- LOG_I(MAC,
- "%d.%d, first 10 payload bytes, TBS size: %d \n",
- frame,
- slot,
- TBS);
- for(int i = 0; i < 10; i++)
- LOG_I(MAC, "byte %d: %x\n", i, ((uint8_t *) buf)[i]);
- }
-#endif
}
/* mark UE as scheduled */
diff --git a/openair2/LAYER2/NR_MAC_gNB/mac_proto.h b/openair2/LAYER2/NR_MAC_gNB/mac_proto.h
index 2c5449affa2..8a314d9b296 100644
--- a/openair2/LAYER2/NR_MAC_gNB/mac_proto.h
+++ b/openair2/LAYER2/NR_MAC_gNB/mac_proto.h
@@ -64,17 +64,6 @@ void clear_nr_nfapi_information(gNB_MAC_INST * gNB,
void gNB_dlsch_ulsch_scheduler(module_id_t module_idP,
frame_t frame_rxP, sub_frame_t slot_rxP);
-int nr_generate_dlsch_pdu(module_id_t Mod_idP,
- NR_UE_sched_ctrl_t *ue_sched_ctl,
- unsigned char *sdus_payload,
- unsigned char *mac_pdu,
- unsigned char num_sdus,
- unsigned short *sdu_lengths,
- unsigned char *sdu_lcids,
- unsigned char drx_cmd,
- unsigned char *ue_cont_res_id,
- unsigned short post_padding);
-
void nr_schedule_ue_spec(module_id_t module_id,
frame_t frame,
sub_frame_t slot);
--
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