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Reorder DLSCH MAC PDU logic

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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
This commit is contained in:
Robert Schmidt
2021-02-07 10:39:39 +01:00
parent 96e1f3597b
commit a18ed9d92d
2 changed files with 97 additions and 164 deletions
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openair2/LAYER2/NR_MAC_gNB/gNB_scheduler_dlsch.c
+97 -153
View File
@@ -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,
@@ -842,109 +801,106 @@ 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 lcid = DL_SCH_LCID_DTCH;
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));
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,
frame,
mindata,
lcid,
header_length_total,
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++;
}
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);
// 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;
}
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;
}
/* 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;
/* 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 = 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,
"%4d.%2d RNTI %04x: %d bytes from DTCH %d (ndata %d, rem TBS %d)\n",
frame,
slot,
rnti,
len,
lcid,
ndata,
TBS);
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: TBS %d B of random data\n", frame, slot, TBS);
// fill dlsch_buffer with random data
for (int i = 0; i < TBS; i++)
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;
}
// 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;
}
}
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;
retInfo->mcsTableIdx = sched_ctrl->mcsTableIdx;
@@ -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 */
openair2/LAYER2/NR_MAC_gNB/mac_proto.h
-11
View File
@@ -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);