system call performance 4.x vs 5.x [and UP vs MP]

[Colin Percival]

At 17:20 28/01/2004, Don Bowman wrote:
>For example, on a 2.0GHz P4-Xeon, HTT enabled, MP kernel, i can
>do ~1M socket/s calls on 4.7, but only ~250K/s on 5.2.
>
>      syscall      4.7        5.2
>        write  1015036     169800
>       socket  1078994     223253
>       select   430564     155077
>gettimeofday   252762     183620
>
>Any suggestion on why such a difference between 4.x and 5.x?

   Mutexes are slow.  The SMP changes in 5.x result in much
better scaling, but there is some inevitable overhead cost.

Colin Percival