Replace kzalloc with mempool to reduce memory fragmentation

Signed-off-by: Nick Huang <[email protected]>

Author: yaodehaung

http_server.c

@@ -7,6 +7,8 @@
 #include "http_parser.h"
 #include "http_server.h"
 
+extern mempool_t *http_buf_pool;
+
 #define CRLF "\r\n"
 
 #define HTTP_RESPONSE_200_DUMMY                               \
@@ -30,7 +32,6 @@
     "Content-Type: text/plain" CRLF "Content-Length: 21" CRLF          \
     "Connection: KeepAlive" CRLF CRLF "501 Not Implemented" CRLF
 
-#define RECV_BUFFER_SIZE 4096
 
 struct http_request {
     struct socket *socket;
@@ -165,7 +166,7 @@ static int http_server_worker(void *arg)
     allow_signal(SIGKILL);
     allow_signal(SIGTERM);
 
-    buf = kzalloc(RECV_BUFFER_SIZE, GFP_KERNEL);
+    buf = mempool_alloc(http_buf_pool, GFP_KERNEL);
     if (!buf) {
         pr_err("can't allocate memory!\n");
         err = -ENOMEM;
@@ -190,7 +191,7 @@ static int http_server_worker(void *arg)
         memset(buf, 0, RECV_BUFFER_SIZE);
     }
 out_free_buf:
-    kfree(buf);
+    mempool_free(buf, http_buf_pool);
 out:
     kernel_sock_shutdown(socket, SHUT_RDWR);
     sock_release(socket);

http_server.h

@@ -3,10 +3,22 @@
 
 #include <net/sock.h>
 
+#define RECV_BUFFER_SIZE 4096
+extern mempool_t *http_buf_pool;
+
 struct http_server_param {
     struct socket *listen_socket;
 };
 
 extern int http_server_daemon(void *arg);
 
+static inline void *http_buf_alloc(gfp_t gfp_mask, void *pool_data)
+{
+    return kzalloc(RECV_BUFFER_SIZE, gfp_mask);
+}
+
+static inline void http_buf_free(void *element, void *pool_data)
+{
+    kfree(element);
+}
 #endif

main.c

@@ -1,7 +1,9 @@
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
 #include <linux/kthread.h>
+#include <linux/mempool.h>
 #include <linux/sched/signal.h>
+#include <linux/slab.h>
 #include <linux/tcp.h>
 #include <linux/version.h>
 #include <net/sock.h>
@@ -10,6 +12,9 @@
 
 #define DEFAULT_PORT 8081
 #define DEFAULT_BACKLOG 100
+#define POOL_MIN_NR 4
+
+mempool_t *http_buf_pool;
 
 static ushort port = DEFAULT_PORT;
 module_param(port, ushort, S_IRUGO);
@@ -154,6 +159,11 @@ static void close_listen_socket(struct socket *socket)
 
 static int __init khttpd_init(void)
 {
+    if (!(http_buf_pool = mempool_create(POOL_MIN_NR, http_buf_alloc,
+                                         http_buf_free, NULL))) {
+        pr_err("failed to create mempool\n");
+        return -ENOMEM;
+    }
     int err = open_listen_socket(port, backlog, &listen_socket);
     if (err < 0) {
         pr_err("can't open listen socket\n");