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Message-ID: <377362e105051904314229b43@mail.gmail.com>
Date: Thu, 19 May 2005 20:31:18 +0900
From: "Tetsuji \"Maverick\" Rai" <tetsuji.rai@gmail.com>
Reply-To: "Tetsuji \"Maverick\" Rai" <tetsuji.rai@gmail.com>
To: Con Kolivas <kernel@kolivas.org>
Subject: Re: HT scheduler: is it really correct? or is it feature of HT?
Cc: linux-kernel@vger.kernel.org
In-Reply-To: <200505192123.24784.kernel@kolivas.org>
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okay,   I'm tired of my temporary hacking (yes, it's just temporary;
only even "nice" values are allowed) and I've just returned to the
original 2.6.11.10  kernel  and read your message :)

I understand it is the "destiny" of HT.

Thanks!

On 5/19/05, Con Kolivas <kernel@kolivas.org> wrote:
> On Thu, 19 May 2005 08:46 pm, Tetsuji "Maverick" Rai wrote:
> > I've done a temporary minor hacking, which tells kernel only the half
> > value of nice in all processes.  Actually idle percentage was lowered,
> > but the response of the main application became slower (as a matter of
> > course.)
> >
> > I'm not sure which is better..if possible I want to take advantages of
> > each one :)   Am I expecting too much?
> 
> Yes you are. Hyperthreading (currently depending on workload) only gives you
> on average 15-25% more cpu with multiple threads. You can't get something for
> nothing. Either the nice 0 task runs slower because a low priority task is
> bound to the sibling, or it runs at the same speed and the low priority task
> runs for less. If you want the nice 19 task to use more cpu run it at nice 0
> - because this is effectively what you are trying to do. If you want more cpu
> you need extra true physical cpus, not logical cores.
> 
> Your code does not do what you think it is doing either. If you want to change
> the bias between nice levels across logical cores search the code for where
> the value of sd->per_cpu_gain is set. It is currently set to 25% and you want
> to increase it (although as I said you will derive no real world benefit as
> your nice 0 task will just slow down).
> 
> Cheers,
> Con
> 


-- 
Luckiest in the world / Weapon of Mass Distraction
http://maverick6664.bravehost.com/
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Background: http://maverick.ns1.name/
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