Re: Route cache performance under stress

["David S. Miller" <davem@xxxxxxxxxx>]

   From: Martin Josefsson <gandalf@xxxxxxxxxxxxxx>
   Date: 22 May 2003 15:03:07 +0200

   On Thu, 2003-05-22 at 13:44, Simon Kirby wrote:
   
   > Nice!  I tested with 300,000 routing table entries and there is no
   > discernable difference in performance from having an empty table. 
   > vmstat shows the same idle time as when the routing table is empty.
   
   How much memory does a table that large use?
   
300,000 * sizeof(struct fib_node)

the second term is:

        (2 * sizeof_pointer_on_this_architecture) + /* 8 or 16 bytes */
        sizeof(u32) + /* 4 bytes */
        4 * sizeof(u8)) /* 4 bytes */

So that's 16 bytes on 32-bit systems, and 24 bytes on 64-bit systems.

Therefore 300,000 routes take up 4.8MB on 32-bit systems and 7.2MB
on 64-bit ones.

I cannot fathom a way to make these any smaller :-)