Re: Performance of -mm2 and -mm4

["Martin J. Bligh" <mbligh@aracnet.com>]

>>>> The -mm4 looks more like sched stuff to me (copy_to/from_user, etc),
>>>> but the -mm2 stuff looks like something else. Buggered if I know what.
>>>> -mm3 didn't compile cleanly, so I didn't bother, but I prob can if you
>>>> like.
>>>> 
>>> 
>>> If you suspect the scheduler, you could try bumping SD_NODES_PER_DOMAIN in 
>>> kernel/sched.c to a larger value (e.g. the number of nodes in your system).  
>>> That'll make the scheduler balance more aggressively across the whole system.
>>> 
>>> 
>> 
>> Try increasing /proc/sys/kernel/base_timeslice as well.
> 
> Or back out nicksched.patch

Yeah, that mostly fixed it.

Kernbench: (make -j N vmlinux, where N = 16 x num_cpus)
                              Elapsed      System        User         CPU
                  2.6.8.1       44.82       97.19      574.55     1497.33
              2.6.8.1-mm4       46.82      107.47      594.15     1497.33
           2.6.8.1-mm4-nn       44.93       96.33      576.44     1496.33

Kernbench: (make -j vmlinux, maximal tasks)
                              Elapsed      System        User         CPU
                  2.6.8.1       43.90       87.76      572.94     1505.67
              2.6.8.1-mm4       45.87       97.60      595.23     1510.00
           2.6.8.1-mm4-nn       44.53       90.71      575.68     1495.67