ULE/yielding patch for testing.

[Yuri Pankov]

On Tue, Oct 02, 2007 at 04:53:33PM -0700, Jeff Roberson wrote:
> Enclosed is a patch that does two things:
>
> 1)  Reduces UP context switch time by over 10% making it faster than 4BSD 
> on UP.  On SMP it's hard to compare since ULE can do as many as 30x as many 
> switches per second on my 8way system.
>
> 2)  Restores old sched_yield() behavior from 6.x.  This was changed in 
> -current unintentionally I think.
>
> I'd appreciate any extra testing.  The ULE context switch time improvements 
> required some changes to the frequency that we recalculate priorities.  I'm 
> mostly interested in hearing whether this causes any regression in normal 
> workloads.
>
> Those of you still using 4BSD can also verify that the yield changes don't 
> cause any problems there.
>
> Thanks,
> Jeff

Jeff,

Patch applied cleanly, though with new kernel I got a panic just after
boot - on xdm startup, I guess (crashdump wasn't saved), a lot of the same messages
(copied by hand):

cpuid = 0
panic: _mtx_lock_sleep: recursed on non-recursive mutex
audit_mtx@/usr/src/sys/security/audit_worker.c:518

and after few seconds system just hangs.

Any hints?

-- 
Yuri Pankov <yuri.pankov at gmail.com>