net: Provide separate configs for TX/RX memory pool for variable bufs

Instead of having a single config specifying the memory pool size for
variable-sized net buffers, have a separate one for TX and RX for better
configuration granularity when optimizing memory usage of the
application.

Deprecate the old configuration but use its value as a default (for now)
for the new configs. This will need to change when the config is
deleted.

Signed-off-by: Robert Lubos <robert.lubos@nordicsemi.no>

doc/connectivity/networking/net_config_guide.rst

@@ -35,8 +35,8 @@ are able to either send or receive at the same time.
   When data is received from the network, it is placed into net_buf data portion.
   Depending on device resources and desired network usage, user can tweak
   the size of the fixed buffer by setting :kconfig:option:`CONFIG_NET_BUF_DATA_SIZE`, and
-  the size of the data pool size by setting :kconfig:option:`CONFIG_NET_BUF_DATA_POOL_SIZE`
-  if variable size buffers are used.
+  the size of the data pool size by setting :kconfig:option:`CONFIG_NET_PKT_BUF_RX_DATA_POOL_SIZE`
+  and :kconfig:option:`CONFIG_NET_PKT_BUF_TX_DATA_POOL_SIZE` if variable size buffers are used.
 
   When using the fixed size data buffers, the memory consumption of network buffers
   can be tweaked by selecting the size of the data part according to what kind of network

subsys/net/ip/Kconfig

@@ -668,12 +668,28 @@ config NET_BUF_DATA_SIZE
 	  This value tells what is the fixed size of each network buffer.
 
 config NET_BUF_DATA_POOL_SIZE
-	int "Size of the memory pool where buffers are allocated from"
+	int "[DEPRECATED] Size of the memory pool where buffers are allocated from"
 	default 4096 if NET_L2_ETHERNET
 	default 2048
 	depends on NET_BUF_VARIABLE_DATA_SIZE
 	help
-	  This value tell what is the size of the memory pool where each
+	  This config is deprecated, use NET_PKT_BUF_RX_DATA_POOL_SIZE and
+	  NET_PKT_BUF_TX_DATA_POOL_SIZE instead.
+
+config NET_PKT_BUF_RX_DATA_POOL_SIZE
+	int "Size of the RX memory pool where buffers are allocated from"
+	default NET_BUF_DATA_POOL_SIZE
+	depends on NET_BUF_VARIABLE_DATA_SIZE
+	help
+	  This value tell what is the size of the RX memory pool where each
+	  network buffer is allocated from.
+
+config NET_PKT_BUF_TX_DATA_POOL_SIZE
+	int "Size of the TX memory pool where buffers are allocated from"
+	default NET_BUF_DATA_POOL_SIZE
+	depends on NET_BUF_VARIABLE_DATA_SIZE
+	help
+	  This value tell what is the size of the TX memory pool where each
 	  network buffer is allocated from.
 
 config NET_PKT_BUF_USER_DATA_SIZE

subsys/net/ip/net_pkt.c

@@ -129,9 +129,9 @@ NET_BUF_POOL_FIXED_DEFINE(tx_bufs, CONFIG_NET_BUF_TX_COUNT, CONFIG_NET_BUF_DATA_
 
 #else /* !CONFIG_NET_BUF_FIXED_DATA_SIZE */
 
-NET_BUF_POOL_VAR_DEFINE(rx_bufs, CONFIG_NET_BUF_RX_COUNT, CONFIG_NET_BUF_DATA_POOL_SIZE,
+NET_BUF_POOL_VAR_DEFINE(rx_bufs, CONFIG_NET_BUF_RX_COUNT, CONFIG_NET_PKT_BUF_RX_DATA_POOL_SIZE,
 			CONFIG_NET_PKT_BUF_USER_DATA_SIZE, NULL);
-NET_BUF_POOL_VAR_DEFINE(tx_bufs, CONFIG_NET_BUF_TX_COUNT, CONFIG_NET_BUF_DATA_POOL_SIZE,
+NET_BUF_POOL_VAR_DEFINE(tx_bufs, CONFIG_NET_BUF_TX_COUNT, CONFIG_NET_PKT_BUF_TX_DATA_POOL_SIZE,
 			CONFIG_NET_PKT_BUF_USER_DATA_SIZE, NULL);
 
 #endif /* CONFIG_NET_BUF_FIXED_DATA_SIZE */

subsys/net/ip/tcp.c

@@ -45,7 +45,7 @@ static int tcp_rx_window =
 #if defined(CONFIG_NET_BUF_FIXED_DATA_SIZE)
 	(CONFIG_NET_BUF_RX_COUNT * CONFIG_NET_BUF_DATA_SIZE) / 3;
 #else
-	CONFIG_NET_BUF_DATA_POOL_SIZE / 3;
+	CONFIG_NET_PKT_BUF_RX_DATA_POOL_SIZE / 3;
 #endif /* CONFIG_NET_BUF_FIXED_DATA_SIZE */
 #endif
 static int tcp_tx_window =
@@ -55,7 +55,7 @@ static int tcp_tx_window =
 #if defined(CONFIG_NET_BUF_FIXED_DATA_SIZE)
 	(CONFIG_NET_BUF_TX_COUNT * CONFIG_NET_BUF_DATA_SIZE) / 3;
 #else
-	CONFIG_NET_BUF_DATA_POOL_SIZE / 3;
+	CONFIG_NET_PKT_BUF_TX_DATA_POOL_SIZE / 3;
 #endif /* CONFIG_NET_BUF_FIXED_DATA_SIZE */
 #endif
 #ifdef CONFIG_NET_TCP_RANDOMIZED_RTO

subsys/net/lib/capture/capture.c

@@ -41,8 +41,10 @@ NET_PKT_SLAB_DEFINE(capture_pkts, CONFIG_NET_CAPTURE_PKT_COUNT);
 NET_BUF_POOL_FIXED_DEFINE(capture_bufs, CONFIG_NET_CAPTURE_BUF_COUNT,
 			  CONFIG_NET_BUF_DATA_SIZE, 4, NULL);
 #else
+#define DATA_POOL_SIZE MAX(NET_PKT_BUF_RX_DATA_POOL_SIZE, NET_PKT_BUF_TX_DATA_POOL_SIZE)
+
 NET_BUF_POOL_VAR_DEFINE(capture_bufs, CONFIG_NET_CAPTURE_BUF_COUNT,
-			CONFIG_NET_BUF_DATA_POOL_SIZE, 4, NULL);
+			DATA_POOL_SIZE, 4, NULL);
 #endif
 
 static sys_slist_t net_capture_devlist;

subsys/net/lib/shell/mem.c

@@ -107,7 +107,8 @@ static int cmd_net_mem(const struct shell *sh, size_t argc, char *argv[])
 #if defined(CONFIG_NET_BUF_FIXED_DATA_SIZE)
 	PR("Fragment length %d bytes\n", CONFIG_NET_BUF_DATA_SIZE);
 #else
-	PR("Fragment data pool size %d bytes\n", CONFIG_NET_BUF_DATA_POOL_SIZE);
+	PR("Fragment RX data pool size %d bytes\n", CONFIG_NET_PKT_BUF_RX_DATA_POOL_SIZE);
+	PR("Fragment TX data pool size %d bytes\n", CONFIG_NET_PKT_BUF_TX_DATA_POOL_SIZE);
 #endif /* CONFIG_NET_BUF_FIXED_DATA_SIZE */
 
 	PR("Network buffer pools:\n");

tests/drivers/build_all/ethernet/prj.conf

@@ -11,7 +11,8 @@ CONFIG_NET_PKT_RX_COUNT=14
 CONFIG_NET_PKT_TX_COUNT=14
 CONFIG_NET_BUF_RX_COUNT=36
 CONFIG_NET_BUF_TX_COUNT=36
-CONFIG_NET_BUF_DATA_POOL_SIZE=4096
+CONFIG_NET_PKT_BUF_RX_DATA_POOL_SIZE=4096
+CONFIG_NET_PKT_BUF_TX_DATA_POOL_SIZE=4096
 
 # Disable L2
 CONFIG_NET_L2_ETHERNET=n

tests/net/6lo/testcase.yaml

@@ -14,4 +14,5 @@ tests:
   net.6lo.variable_buf_size:
     extra_configs:
       - CONFIG_NET_BUF_VARIABLE_DATA_SIZE=y
-      - CONFIG_NET_BUF_DATA_POOL_SIZE=4096
+      - CONFIG_NET_PKT_BUF_RX_DATA_POOL_SIZE=4096
+      - CONFIG_NET_PKT_BUF_TX_DATA_POOL_SIZE=4096

tests/net/all/prj.conf

@@ -25,7 +25,8 @@ CONFIG_NET_BUF_LOG_LEVEL_DBG=y
 CONFIG_NET_BUF_WARN_ALLOC_INTERVAL=2
 CONFIG_NET_BUF_SIMPLE_LOG=y
 CONFIG_NET_BUF_POOL_USAGE=y
-#CONFIG_NET_BUF_DATA_POOL_SIZE=4096
+#CONFIG_NET_PKT_BUF_RX_DATA_POOL_SIZE=4096
+#CONFIG_NET_PKT_BUF_TX_DATA_POOL_SIZE=4096
 CONFIG_NET_BUF_FIXED_DATA_SIZE=y
 CONFIG_NET_BUF_VARIABLE_DATA_SIZE=n
 CONFIG_NET_PKT_RX_COUNT=10

tests/net/ipv6/testcase.yaml

@@ -10,4 +10,5 @@ tests:
   net.ipv6.variable_buf_size:
     extra_configs:
       - CONFIG_NET_BUF_VARIABLE_DATA_SIZE=y
-      - CONFIG_NET_BUF_DATA_POOL_SIZE=4096
+      - CONFIG_NET_PKT_BUF_RX_DATA_POOL_SIZE=4096
+      - CONFIG_NET_PKT_BUF_TX_DATA_POOL_SIZE=4096

tests/net/tcp/testcase.yaml

@@ -13,4 +13,5 @@ tests:
   net.tcp.variable_buf_size:
     extra_configs:
       - CONFIG_NET_BUF_VARIABLE_DATA_SIZE=y
-      - CONFIG_NET_BUF_DATA_POOL_SIZE=4096
+      - CONFIG_NET_PKT_BUF_RX_DATA_POOL_SIZE=4096
+      - CONFIG_NET_PKT_BUF_TX_DATA_POOL_SIZE=4096