4BSD/ULE numbers...

David Xu davidxu at freebsd.org
Mon Sep 26 15:37:14 PDT 2005

Kris Kennaway wrote:

>On Mon, Sep 26, 2005 at 06:47:27PM +0200, Emanuel Strobl wrote:
>>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.
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. :)

David Xu

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