[PATCH RFC] 2.4.18+ cache align some tcp globals

This makes some of the tcp globals cache aligned in
SMP systems  (trying to address cacheline bouncing
on busy systems).

Patch applies to 2.4.18.

thanks,
Nivedita


--- tcp.c       Fri Dec 21 09:42:05 2001
+++ tcp.c.new   Sun May 26 19:55:45 2002
@@ -266,20 +266,22 @@
 kmem_cache_t *tcp_bucket_cachep;
 kmem_cache_t *tcp_timewait_cachep;
 
-atomic_t tcp_orphan_count = ATOMIC_INIT(0);
+atomic_t tcp_orphan_count ____cacheline_aligned_in_smp = ATOMIC_INIT(0);
 
 int sysctl_tcp_mem[3];
 int sysctl_tcp_wmem[3] = { 4*1024, 16*1024, 128*1024 };
 int sysctl_tcp_rmem[3] = { 4*1024, 87380, 87380*2 };
 
-atomic_t tcp_memory_allocated; /* Current allocated memory. */
-atomic_t tcp_sockets_allocated;        /* Current number of TCP sockets. */
+/* Current allocated memory. */
+atomic_t tcp_memory_allocated ____cacheline_aligned_in_smp;
+/* Current number of TCP sockets. */
+atomic_t tcp_sockets_allocated ____cacheline_aligned_in_smp;
 
 /* Pressure flag: try to collapse.
  * Technical note: it is used by multiple contexts non atomically.
  * All the tcp_mem_schedule() is of this nature: accounting
  * is strict, actions are advisory and have some latency. */
-int tcp_memory_pressure;
+int tcp_memory_pressure ____cacheline_aligned_in_smp;
 
 #define TCP_PAGES(amt) (((amt)+TCP_MEM_QUANTUM-1)/TCP_MEM_QUANTUM)