From 97c69dc4a4f5b8946197c38f85c4919fc2804c31 Mon Sep 17 00:00:00 2001
From: Robert Schmidt <robert.schmidt@eurecom.fr>
Date: Thu, 7 Jun 2018 11:58:34 +0200
Subject: [PATCH] Drop traffic in PDCP if RLC buffer is full
If the buffer in the RLC is full, testing the buffer state over and over again
slows the DL traffic down. In order to circumvent this, the PDCP will drop any
data during a configurable time (compile-time) before it delivers data to RLC
again.
To change this, see the constant TM_SKIP_FULL_BUF_MS in pdcp.h.
---
openair2/LAYER2/PDCP_v10.1.0/pdcp.c | 46 +++++++++++++++++++----------
openair2/LAYER2/PDCP_v10.1.0/pdcp.h | 2 ++
openair2/LAYER2/RLC/rlc.h | 1 +
3 files changed, 34 insertions(+), 15 deletions(-)
diff --git a/openair2/LAYER2/PDCP_v10.1.0/pdcp.c b/openair2/LAYER2/PDCP_v10.1.0/pdcp.c
index 4731039c1a..8b96542e33 100644
--- a/openair2/LAYER2/PDCP_v10.1.0/pdcp.c
+++ b/openair2/LAYER2/PDCP_v10.1.0/pdcp.c
@@ -169,6 +169,11 @@ boolean_t pdcp_data_req(
start_meas(&UE_pdcp_stats[ctxt_pP->module_id].data_req);
}
+ for (pdcp_uid = 0; pdcp_uid < MAX_MOBILES_PER_ENB; ++pdcp_uid) {
+ if (pdcp_enb[ctxt_pP->module_id].rnti[pdcp_uid] == ctxt_pP->rnti)
+ break;
+ }
+
// PDCP transparent mode for MBMS traffic
if (modeP == PDCP_TRANSMISSION_MODE_TRANSPARENT) {
@@ -366,13 +371,24 @@ boolean_t pdcp_data_req(
LOG_DUMPMSG(PDCP,DEBUG_PDCP,(char *)pdcp_pdu_p->data,pdcp_pdu_size,
"[MSG] PDCP DL %s PDU on rb_id %d\n",(srb_flagP)? "CONTROL" : "DATA", rb_idP);
- rlc_status = rlc_data_req(ctxt_pP, srb_flagP, MBMS_FLAG_NO, rb_idP, muiP, confirmP, pdcp_pdu_size, pdcp_pdu_p
+ /* if RLC buffer for this UE has been full, we want to skip all subsequent
+ * traffic for TM_SKIP_FULL_BUF_MS ms. Afterwards, it will be checkd again */
+ if (pdcp_enb[ctxt_pP->module_id].time_buf_full[pdcp_uid] == 0
+ || pdcp_enb[ctxt_pP->module_id].sfn - pdcp_enb[ctxt_pP->module_id].time_buf_full[pdcp_uid] >= TM_SKIP_FULL_BUF_MS) {
+ pdcp_enb[ctxt_pP->module_id].time_buf_full[pdcp_uid] = 0;
+ rlc_status = rlc_data_req(ctxt_pP, srb_flagP, MBMS_FLAG_NO, rb_idP, muiP,
+ confirmP, pdcp_pdu_size, pdcp_pdu_p
#if (RRC_VERSION >= MAKE_VERSION(14, 0, 0))
- ,sourceL2Id
- ,destinationL2Id
+ ,sourceL2Id
+ ,destinationL2Id
#endif
- );
-
+ );
+ } else {
+ /* RLC would free pdcp_pdu_p, but since we skip it, have to do it
+ * ourselves and fake normal operation */
+ free_mem_block(pdcp_pdu_p, __func__);
+ rlc_status = RLC_OP_SKIPPED_FUL_BUF;
+ }
}
switch (rlc_status) {
@@ -392,10 +408,19 @@ boolean_t pdcp_data_req(
break;
case RLC_OP_STATUS_OUT_OF_RESSOURCES:
+ pdcp_enb[ctxt_pP->module_id].time_buf_full[pdcp_uid] = pdcp_enb[ctxt_pP->module_id].sfn;
LOG_W(PDCP, "Data sending request over RLC failed with 'Out of Resources' reason!\n");
+ int h = TM_SKIP_FULL_BUF_MS;
+ LOG_W(PDCP, "Blocking incoming traffic for %d ms\n", h);
ret= FALSE;
break;
+ case RLC_OP_SKIPPED_FUL_BUF:
+ LOG_D(PDCP, "Skipping RLC request due to full buffer\n");
+ /* fake good return so that GTP doesn't spam us */
+ ret = TRUE;
+ break;
+
default:
LOG_W(PDCP, "RLC returned an unknown status code after PDCP placed the order to send some data (Status Code:%d)\n", rlc_status);
ret= FALSE;
@@ -408,16 +433,6 @@ boolean_t pdcp_data_req(
stop_meas(&UE_pdcp_stats[ctxt_pP->module_id].data_req);
}
- /*
- * Control arrives here only if rlc_data_req() returns RLC_OP_STATUS_OK
- * so we return TRUE afterwards
- */
-
- for (pdcp_uid=0; pdcp_uid< MAX_MOBILES_PER_ENB;pdcp_uid++){
- if (pdcp_enb[ctxt_pP->module_id].rnti[pdcp_uid] == ctxt_pP->rnti )
- break;
- }
-
//LOG_I(PDCP,"ueid %d lcid %d tx seq num %d\n", pdcp_uid, rb_idP+rb_offset, current_sn);
Pdcp_stats_tx[ctxt_pP->module_id][pdcp_uid][rb_idP+rb_offset]++;
Pdcp_stats_tx_tmp_w[ctxt_pP->module_id][pdcp_uid][rb_idP+rb_offset]++;
@@ -1066,6 +1081,7 @@ void pdcp_add_UE(const protocol_ctxt_t* const ctxt_pP){
if (pdcp_enb[ctxt_pP->module_id].rnti[i] == 0 ){
pdcp_enb[ctxt_pP->module_id].rnti[i]=ctxt_pP->rnti;
pdcp_enb[ctxt_pP->module_id].uid[i]=i;
+ pdcp_enb[ctxt_pP->module_id].time_buf_full[i] = 0;
pdcp_enb[ctxt_pP->module_id].num_ues++;
printf("add new uid is %d %x\n\n", i, ctxt_pP->rnti);
// ret=1;
diff --git a/openair2/LAYER2/PDCP_v10.1.0/pdcp.h b/openair2/LAYER2/PDCP_v10.1.0/pdcp.h
index 054bb5fac4..1bfe4e022a 100644
--- a/openair2/LAYER2/PDCP_v10.1.0/pdcp.h
+++ b/openair2/LAYER2/PDCP_v10.1.0/pdcp.h
@@ -106,6 +106,8 @@ typedef struct pdcp_enb_s {
uint16_t uid[MAX_MOBILES_PER_ENB];
rnti_t rnti[MAX_MOBILES_PER_ENB];
uint16_t num_ues;
+#define TM_SKIP_FULL_BUF_MS (500)
+ uint64_t time_buf_full[MAX_MOBILES_PER_ENB];
uint64_t sfn;
frame_t frame;
diff --git a/openair2/LAYER2/RLC/rlc.h b/openair2/LAYER2/RLC/rlc.h
index 8c557188a2..dfb22f1a0d 100644
--- a/openair2/LAYER2/RLC/rlc.h
+++ b/openair2/LAYER2/RLC/rlc.h
@@ -67,6 +67,7 @@ typedef uint64_t hash_key_t;
#define RLC_OP_STATUS_BAD_PARAMETER 22
#define RLC_OP_STATUS_INTERNAL_ERROR 2
#define RLC_OP_STATUS_OUT_OF_RESSOURCES 3
+#define RLC_OP_SKIPPED_FUL_BUF 4
#define RLC_MUI_UNDEFINED (mui_t)0
--
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