Re: [patch] Convert sockets_in_use to use per_cpu areas

[Ravikiran G Thirumalai <kiran@xxxxxxxxxx>]

On Mon, Dec 23, 2002 at 12:16:32PM -0800, David S. Miller wrote:
>...     
>    -static union {
>    -  int     counter;
>    -  char    __pad[SMP_CACHE_BYTES];
>    -} sockets_in_use[NR_CPUS] __cacheline_aligned = {{0}};
>    +static DEFINE_PER_CPU(int, sockets_in_use);
> 
> You have to provide an explicit initializer for DEFINE_PER_CPU
> declarations or you break some platforms with older GCC's which
> otherwise won't put it into the proper section.
> 

Ok, here's the modified patch...

Thanks,
Kiran


diff -ruN -X dontdiff linux-2.5.52/net/socket.c 
sockets_in_use-2.5.52/net/socket.c
--- linux-2.5.52/net/socket.c   Mon Dec 16 07:37:53 2002
+++ sockets_in_use-2.5.52/net/socket.c  Tue Dec 24 05:11:36 2002
@@ -189,10 +189,7 @@
  *     Statistics counters of the socket lists
  */
 
-static union {
-       int     counter;
-       char    __pad[SMP_CACHE_BYTES];
-} sockets_in_use[NR_CPUS] __cacheline_aligned = {{0}};
+static DEFINE_PER_CPU(int, sockets_in_use) = 0;
 
 /*
  *     Support routines. Move socket addresses back and forth across the 
kernel/user
@@ -475,7 +472,8 @@
        inode->i_uid = current->fsuid;
        inode->i_gid = current->fsgid;
 
-       sockets_in_use[smp_processor_id()].counter++;
+       get_cpu_var(sockets_in_use)++;
+       put_cpu_var(sockets_in_use);
        return sock;
 }
 
@@ -511,7 +509,8 @@
        if (sock->fasync_list)
                printk(KERN_ERR "sock_release: fasync list not empty!\n");
 
-       sockets_in_use[smp_processor_id()].counter--;
+       get_cpu_var(sockets_in_use)--;
+       put_cpu_var(sockets_in_use);
        if (!sock->file) {
                iput(SOCK_INODE(sock));
                return;
@@ -1851,7 +1850,7 @@
        int counter = 0;
 
        for (cpu = 0; cpu < NR_CPUS; cpu++)
-               counter += sockets_in_use[cpu].counter;
+               counter += per_cpu(sockets_in_use, cpu);
 
        /* It can be negative, by the way. 8) */
        if (counter < 0)