unexpected idprio 31 behavior on 9.2-BETA2 and 9.2-RC1

[Harald Schmalzbauer]

Bezüglich John Baldwin's Nachricht vom 04.09.2013 15:58 (localtime):
> On Thursday, August 08, 2013 10:41:12 am Eric van Gyzen wrote:
>> On 08/08/2013 09:19, Eric van Gyzen wrote:
>>> On 08/06/2013 14:23, J David wrote:
>>>> On Tue, Aug 6, 2013 at 1:59 PM, Eric van Gyzen <eric at vangyzen.net> wrote:
>>>>>> on an otherwise idle amd64 system with 4 CPUs.  The first command in 
> the
>>>>>> build.log file:
>>>>>>
>>>>>>     rm -rf /usr/obj/home/freebsd/tmp
>>>>>>
>>>>>> took over three minutes.  It should have taken about three /seconds/.
>>>>>>
>>>>>> "uptime" reported a load average of around 1.00.
>>>>>> "top" showed no threads (user or kernel) using CPU.
>>>>>> "iostat" showed an average of less than 20 tps on ada0.
>>>>>> "rm" was usually in the RUN state.
>>>> We are looking at something similar.  Would you be able to try to
>>>> reproduce it using a kernel with:
>>>>
>>>> nooptions	SCHED_ULE
>>>> options		SCHED_4BSD
>>>>
>>>> to see if it makes a difference?  It seems to, but the problem is
>>>> inconsistent enough that I can't be sure.
>>> The 4BSD scheduler does //not// exhibit this problem.  I tested with the
>>> latest releng/9.2 (r254054) and an otherwise GENERIC config.
>>
>> To be thorough, I built a GENERIC kernel at the same rev, and it still
>> exhibits the problem.
> 
> Please try this change:
> 
> Index: sched_ule.c
> ===================================================================
> --- sched_ule.c	(revision 255020)
> +++ sched_ule.c	(working copy)
> @@ -243,7 +243,7 @@ struct tdq {
>  	int		tdq_transferable;	/* Transferable thread count. */
>  	short		tdq_switchcnt;		/* Switches this tick. */
>  	short		tdq_oldswitchcnt;	/* Switches last tick. */
> -	u_char		tdq_lowpri;		/* Lowest priority thread. */
> +	u_short		tdq_lowpri;		/* Lowest priority thread. */
>  	u_char		tdq_ipipending;		/* IPI pending. */
>  	u_char		tdq_idx;		/* Current insert index. */
>  	u_char		tdq_ridx;		/* Current removal index. */
> @@ -2323,7 +2323,7 @@ sched_choose(void)
>  		tdq->tdq_lowpri = td->td_priority;
>  		return (td);
>  	}
> -	tdq->tdq_lowpri = PRI_MAX_IDLE;
> +	tdq->tdq_lowpri = PRI_MAX_IDLE + 1;
>  	return (PCPU_GET(idlethread));
>  }

Hello,

the fix above still applies cleanly to 9.3-RC3.
Was ist solved differently? Or just slipped through?

Thanks,

-Harry

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