4BSD/ULE numbers...

Kris Kennaway kris at obsecurity.org
Mon Sep 26 15:44:55 PDT 2005

On Tue, Sep 27, 2005 at 06:37:05AM +0800, David Xu wrote:
> Kris Kennaway wrote:
> >On Mon, Sep 26, 2005 at 06:47:27PM +0200, Emanuel Strobl wrote:
> > 
> >
> >>Hello,
> >>
> >>I tried ULE with BETA5 and for me it felt a bit sluggish when making 
> >>ports.
> >>So I did some "realworld" simulation and compared 4BSD/ULE to see what 
> >>numbers tell me. And the prooved my feeling right.
> >>It seems that ULE is priorizing nice a little higher, but in general the 
> >>output of the 4 BSD machine is higher and finishing the tests took not so 
> >>long as with ULE, especially the "make configure" differs horribly.
> >>   
> >>
> >
> >That's consistent with my testing.  ULE seems a bit more stable now in
> >6.0 (except on my large SMP machines, which reboot spontaneously under
> >moderate load), but it doesn't perform as well as 4BSD under real
> >application workloads.
> >
> >Kris
> >
> I am fiddling it, although I don't know when I can finish.
> In fact, the ULE code in my perforce has same performance as
> 4BSD, at least this is true on my Dual PIII machine. the real
> advantage is ULE can be HTT friendly if it make it correctly,
> for example physical / logical CPU balance, if system has two
> HTT enabled physical CPU, if system has too CPU hog threads,
> you definitely want the two threads to run on the two physical
> cpu, not in same phyiscal cpu.
> but current it is not. Another advantage is when sched_lock pushes
> down, I know current sched_lock is a Giant lock between large
> number of CPU, also I don't know when sched_lock will be pushed
> down, sched_lock is abused in many place, they really can be replaced
> by another spin lock. :)

I'd love a way to measure sched_lock contention..I'm sure it's a
factor on e.g. my machines with >=10 CPUs, but mutex profiling doesn't
see it because it's a spinlock.


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