drivers: rmnet: shs: add segmentation levels for slow start flows

Adds various levels of segmentation for flows in TCP slow start.
Instead of segmentation causing all packets to be 1500 bytes,
we will control how much larger packets get broken up by
passing segs_per_skb, which indicates how many MTU sizes packets
should be in the newly segmented SKBs. i.e. segs_per_skb = 2
means 2*MTU can be passed in a segmented skb.

Change-Id: I422a794f3b1d3f2e313ce8f89695a536984cd947
Acked-by: Ryan Chapman <rchapman@qti.qualcomm.com>
Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>

1 files changed, 12 insertions, 10 deletions

diff --git a/drivers/rmnet/shs/rmnet_shs_wq.c b/drivers/rmnet/shs/rmnet_shs_wq.c
index 53f5826..2678d8b 100644
--- a/drivers/rmnet/shs/rmnet_shs_wq.c
+++ b/drivers/rmnet/shs/rmnet_shs_wq.c
@@ -42,6 +42,8 @@ MODULE_PARM_DESC(rmnet_shs_cpu_prio_dur, "Priority ignore duration (wq intervals
 
 #define PRIO_BACKOFF ((!rmnet_shs_cpu_prio_dur) ? 2 : rmnet_shs_cpu_prio_dur)
 
+#define RMNET_SHS_SEGS_PER_SKB_DEFAULT (2)
+
 unsigned int rmnet_shs_wq_interval_ms __read_mostly = RMNET_SHS_WQ_INTERVAL_MS;
 module_param(rmnet_shs_wq_interval_ms, uint, 0644);
 MODULE_PARM_DESC(rmnet_shs_wq_interval_ms, "Interval between wq runs (ms)");
@@ -411,7 +413,7 @@ void rmnet_shs_wq_create_new_flow(struct rmnet_shs_skbn_s *node_p)
 		/* Start TCP flows with segmentation if userspace connected */
 		if (rmnet_shs_userspace_connected &&
 		    node_p->hstats->skb_tport_proto == IPPROTO_TCP)
-			node_p->hstats->segment_enable = 1;
+			node_p->hstats->segs_per_skb = RMNET_SHS_SEGS_PER_SKB_DEFAULT;
 
 		node_p->hstats->node = node_p;
 		node_p->hstats->c_epoch = RMNET_SHS_SEC_TO_NSEC(time.tv_sec) +
@@ -1291,7 +1293,7 @@ int rmnet_shs_wq_try_to_move_flow(u16 cur_cpu, u16 dest_cpu, u32 hash_to_move,
 }
 
 /* Change flow segmentation, return 1 if set, 0 otherwise */
-int rmnet_shs_wq_set_flow_segmentation(u32 hash_to_set, u8 seg_enable)
+int rmnet_shs_wq_set_flow_segmentation(u32 hash_to_set, u8 segs_per_skb)
 {
 	struct rmnet_shs_skbn_s *node_p;
 	struct rmnet_shs_wq_hstat_s *hstat_p;
@@ -1311,22 +1313,22 @@ int rmnet_shs_wq_set_flow_segmentation(u32 hash_to_set, u8 seg_enable)
 		if (hstat_p->hash != hash_to_set)
 			continue;
 
-		rm_err("SHS_HT: >> segmentation on hash 0x%x enable %u",
-		       hash_to_set, seg_enable);
+		rm_err("SHS_HT: >> segmentation on hash 0x%x segs_per_skb %u",
+		       hash_to_set, segs_per_skb);
 
 		trace_rmnet_shs_wq_high(RMNET_SHS_WQ_FLOW_STATS,
 				RMNET_SHS_WQ_FLOW_STATS_SET_FLOW_SEGMENTATION,
-				hstat_p->hash, seg_enable,
+				hstat_p->hash, segs_per_skb,
 				0xDEF, 0xDEF, hstat_p, NULL);
 
-		node_p->hstats->segment_enable = seg_enable;
+		node_p->hstats->segs_per_skb = segs_per_skb;
 		spin_unlock_irqrestore(&rmnet_shs_ht_splock, ht_flags);
 		return 1;
 	}
 	spin_unlock_irqrestore(&rmnet_shs_ht_splock, ht_flags);
 
-	rm_err("SHS_HT: >> segmentation on hash 0x%x enable %u not set - hash not found",
-	       hash_to_set, seg_enable);
+	rm_err("SHS_HT: >> segmentation on hash 0x%x segs_per_skb %u not set - hash not found",
+	       hash_to_set, segs_per_skb);
 	return 0;
 }
 
@@ -1966,7 +1968,7 @@ void rmnet_shs_wq_filter(void)
 			continue;
 		}
 
-		if (hnode->node->hstats->segment_enable) {
+		if (hnode->node->hstats->segs_per_skb > 0) {
 			rmnet_shs_cpu_node_tbl[cur_cpu].seg++;
 		}
 	}
@@ -2003,7 +2005,7 @@ void rmnet_shs_wq_update_stats(void)
 				}
 			} else {
 				/* Disable segmentation if userspace gets disconnected connected */
-				hnode->node->hstats->segment_enable = 0;
+				hnode->node->hstats->segs_per_skb = 0;
 			}
 		}
 	}