interconnect: increase UDP unack queue size and fix mem size unit handling

Fix calculation of per-queue capacity in SetupUDPIFCInterconnect by
properly converting gp_interconnect_mem_size from MB to bytes. Without
this conversion, the derived send queue depth could be severely
underestimated, leading to suboptimal throughput.

Author: yjhjstz

contrib/interconnect/udp/ic_udpifc.c

@@ -595,7 +595,7 @@ static ICGlobalControlInfo ic_control_info;
 
 #define MAX_SEQS_IN_DISORDER_ACK (4)
 
-#define MAX_QUEUE_SIZE (64)
+#define MAX_QUEUE_SIZE (12)
 /*
  * UnackQueueRing
  *
@@ -3753,7 +3753,7 @@ SetupUDPIFCInterconnect(EState *estate)
 			Gp_interconnect_queue_depth == 4 &&
 			Gp_interconnect_snd_queue_depth == 2)
 		{
-			int32 perQueue = Gp_interconnect_mem_size /
+			int32 perQueue = ((int64)Gp_interconnect_mem_size * 1024 * 1024) /
 				(Gp_max_packet_size * sliceNum);
 
 			calcSndDepth = Max(Gp_interconnect_snd_queue_depth, perQueue / 2);

contrib/udp2/ic_udp2.c

@@ -47,7 +47,7 @@
 #include "ic_types.h"
 #include "udp2/ic_udp2.h"
 
-#define MAX_QUEUE_SIZE (64)
+#define MAX_QUEUE_SIZE (12)
 
 #define HandleLastError() \
 do { \
@@ -179,7 +179,7 @@ SetupInterconnectUDP2(EState *estate)
 		Gp_interconnect_queue_depth == 4 &&
 		Gp_interconnect_snd_queue_depth == 2)
 	{
-		int32 perQueue = Gp_interconnect_mem_size /
+		int32 perQueue = ((int64)Gp_interconnect_mem_size * 1024 * 1024) /
 			(Gp_max_packet_size * sliceNum);
 
 		calcSndDepth = Max(Gp_interconnect_snd_queue_depth, perQueue / 2);

src/backend/utils/misc/guc_gp.c

@@ -3788,7 +3788,7 @@ struct config_int ConfigureNamesInt_gp[] =
 			NULL
 		},
 		&Gp_interconnect_mem_size,
-		10, 1, 1024,
+		1, 1, 1024,
 		NULL, NULL, NULL
 	},