From: Con Kolivas <kernel@kolivas.org>
To: Jos Hulzink <josh@stack.nl>,
       linux kernel mailing list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] 2.6.1 Hyperthread smart "nice"
Date: Thu, 29 Jan 2004 21:28:20 +1100
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On Thu, 29 Jan 2004 20:39, Jos Hulzink wrote:
> On Thursday 29 Jan 2004 09:17, Con Kolivas wrote:
> > Hi all
> >
> > This patch (together with the ht base patch) will not allow a priority
> > >10 difference to run concurrently on both siblings, instead putting the
> > low priority one to sleep. Overall if you run concurrent nice 0 and nice
> > 20 tasks with this patch your cpu throughput will drop during heavy
> > periods by up to 10% (the hyperthread benefit), but your nice 0 task will
> > run about 90% faster. It has no effect if you don't run any tasks at
> > different "nice" levels. It does not modify real time tasks or kernel
> > threads, and will allow niced tasks to run while a high priority kernel
> > thread is running on the sibling cpu.
>
> If I read you correctly, if one thread has nothing else to do but the nice
> 0 task, the nice 20 task will never be scheduled at all ? Sounds like not
> the perfect solution to me...

Wrong.. there is the matter of the other runqueue in smp mode :)

Con

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