Re: ULE/yielding patch for testing.

On Tue, Oct 02, 2007 at 09:53:29PM -0700, Jeff Roberson wrote:
> On Wed, 3 Oct 2007, Yuri Pankov wrote:
>
>> On Tue, Oct 02, 2007 at 07:55:02PM -0700, Jeff Roberson wrote:
>>> On Wed, 3 Oct 2007, Yuri Pankov wrote:
>>>
>>>> On Wed, Oct 03, 2007 at 04:50:09AM +0400, Yuri Pankov wrote:
>>>>> 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_at_/usr/src/sys/security/audit_worker.c:518
>>>>>
>>>>> and after few seconds system just hangs.
>>>>>
>>>>> Any hints?
>>>>>
>>>>> --
>>>>> Yuri Pankov <yuri.pankov_at_gmail.com>
>>>>
>>>> Sorry for being so verbose...
>>>
>>> Did you 'make depend' as well?  If you patch -R < yield.diff does this
>>> kernel work?  I'm not sure how my changes could cause this type of bug.
>>>
>>> Thanks,
>>> Jeff
>>>
>>
>> I'm rebuilt kernel with and without your patch (with clean /usr/obj/ every 
>> time)
>> using `make kernel KERNCONF=DARKLIGHT` just to be sure.
>>
>> Without your patch, system seems to run stable. With it - I get hard hangs 
>> upon
>> just loading X or upon xdm startup or after xdm login, every time the 
>> same. No
>> messages now, just hangs. Nothing suspicious in /var/log/messages, etc.
>>
>> Xorg 7.3 with xf86-video-nv, all ports built yesterday (it was fresh 
>> install).
>>
>> Anything that I should look at? (as it can be just pilot error).
>
> The attached diff is only the changes the fix yield() and sched_yield() to 
> pre-CURRENT states.  Can you try this on its own and let me know if it 
> works so I can narrow down the part of the patch causing trouble?
>
> Thanks,
> Jeff
>

Works fine so far (at least I'm able to login through xdm and run apps :-).

Thanks Jeff.

-- 
Yuri Pankov <yuri.pankov_at_gmail.com>