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Subject: Re: [patch] voluntary-preempt-2.6.8.1-P8
From: Lee Revell <rlrevell@joe-job.com>
To: Ingo Molnar <mingo@elte.hu>
Cc: linux-kernel <linux-kernel@vger.kernel.org>
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On Mon, 2004-08-23 at 18:52, Ingo Molnar wrote:
> * Lee Revell <rlrevell@joe-job.com> wrote:
> > Should this fix the 500+ usec latency I saw in rt_garbage_collect? 
> > This one took a while to occur (overnight).
> 
> i dont think it will. Does the patch below help?
> 
> 	Ingo
> 
> --- net/ipv4/route.c.orig
> +++ net/ipv4/route.c
> @@ -738,7 +738,7 @@ static int rt_garbage_collect(void)
>  
>  		if (atomic_read(&ipv4_dst_ops.entries) < ip_rt_max_size)
>  			goto out;
> -	} while (!in_softirq() && time_before_eq(jiffies, now));
> +	} while (!in_softirq() && time_before_eq(jiffies, now) && !need_resched());
>  
>  	if (atomic_read(&ipv4_dst_ops.entries) < ip_rt_max_size)
>  		goto out;
> 

Nope, the above does not actually fix it.  I got a 716 usec latency in
rt_garbage_collect:

http://krustophenia.net/testresults.php?dataset=2.6.8.1-P9#/var/www/2.6.8.1-P9/trace12.txt

I believe this is associated with heavy route cache activity, I did not
see this one again until I left a gnutella client running overnight.

Lee