Re: [PATCH] Give kjournald a IOPRIO_CLASS_RT io priority

[Arjan van de Ven <arjan@infradead.org>]

On Thu, 2 Oct 2008 13:24:57 -0700
Andrew Morton <akpm@linux-foundation.org> wrote:

> Of course, that could all be wrong and we could be stuck somewhere
> else.  A good way to diagnose this stuff would be
> 
> --- a/kernel/sched.c~a
> +++ a/kernel/sched.c
> @@ -5567,10 +5567,14 @@ EXPORT_SYMBOL(yield);
>  void __sched io_schedule(void)
>  {
>  	struct rq *rq = &__raw_get_cpu_var(runqueues);
> +	unsigned long in, out;
>  
>  	delayacct_blkio_start();
>  	atomic_inc(&rq->nr_iowait);
> +	in = jiffies;
>  	schedule();
> +	out = jiffies;
> +	WARN_ON(time_after(out, in + 1 * HZ));
>  	atomic_dec(&rq->nr_iowait);
>  	delayacct_blkio_end();
>  }
> _
> 
> perhaps for varying values of "1".

I'll run with this. (well with a value of "1000" for 1 ;-)

Also I'll tell latencytop to give me the full backtrace as well ;-)


-- 
Arjan van de Ven 	Intel Open Source Technology Centre
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