[SPARC64]: Dynamically grow TSB in response to RSS growth.

As the RSS grows, grow the TSB in order to reduce the likelyhood
of hash collisions and thus poor hit rates in the TSB.

This definitely needs some serious tuning.

Signed-off-by: David S. Miller <davem@davemloft.net>

include/asm-sparc64/mmu.h

@@ -100,6 +100,7 @@ struct tsb {
 typedef struct {
 	unsigned long	sparc64_ctx_val;
 	struct tsb	*tsb;
+	unsigned long	tsb_rss_limit;
 	unsigned long	tsb_nentries;
 	unsigned long	tsb_reg_val;
 	unsigned long	tsb_map_vaddr;