ULE/SCHED_SMP diff for 7.0, buildkernel & thanks.

[Wes Morgan]

On Tue, 17 Jul 2007, Jeff Roberson wrote:

> With regards to buildkernel times;  I do not want to sacrafice performance on 
> other benchmarks to improve buildkernel.  The problem is that 4BSD is as 
> agressive as possible at scheduling work on idle cores.  This behavior that 
> helps one buildworld hurts on other, in my opinion, more important 
> benchmarks.
>
> For example: http://people.freebsd.org/~jeff/sysbench.png
>
> ULE is 33% faster than SCHED_4BSD at this mysql test.  This is a direct 
> result of prefering to idle to make more efficient scheduling decisions. ULE 
> is also faster at various networking benchmarks for similar reasons.
>
> I also believe that while the real time may be slower on buildworld the 
> system and user time will be smaller by a degree greater than the delta in 
> real time.  This means that while you're building packages you have a little 
> more cpu time leftover to handle other tasks.  Furthermore, as the number of 
> cores goes up things start to tip in favor of ULE although this is somewhat 
> because it's harder for even 4BSD to keep them busy due to disk bandwidth.
>
> Thanks everyone for testing.  Can someone confirm that they have tested with 
> x86 rather than amd64?  I will probably commit later today.

Running fine on my core duo x86 so far. Interactivity seems good with a 
buildworld -j4 going on.