linux-kernel - Re: [PATCH 8/15] sched: Add parameter sched_mn_power_savings to control MN domain sched policy

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Message-ID: <20090824153229.GL6474@dirshya.in.ibm.com>
Date:	Mon, 24 Aug 2009 21:02:29 +0530
From:	Vaidyanathan Srinivasan <svaidy@...ux.vnet.ibm.com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Andreas Herrmann <andreas.herrmann3@....com>,
	Ingo Molnar <mingo@...e.hu>, linux-kernel@...r.kernel.org,
	Gautham Shenoy <ego@...ibm.com>,
	Srivatsa Vaddagiri <vatsa@...ibm.com>,
	Dipankar Sarma <dipankar@...ibm.com>,
	Balbir Singh <balbir@...ux.vnet.ibm.com>,
	Arun R Bharadwaj <arun@...ux.vnet.ibm.com>
Subject: Re: [PATCH 8/15] sched: Add parameter sched_mn_power_savings to
 control MN domain sched policy

* Peter Zijlstra <peterz@...radead.org> [2009-08-24 16:56:18]:

> On Thu, 2009-08-20 at 15:39 +0200, Andreas Herrmann wrote:
> > Signed-off-by: Andreas Herrmann <andreas.herrmann3@....com>
> > ---
> 
> > +#ifdef CONFIG_SCHED_MN
> > +	if (!err && mc_capable())
> > +		err = sysfs_create_file(&cls->kset.kobj,
> > +					&attr_sched_mn_power_savings.attr);
> > +#endif
> 
> *sigh* another crappy sysfs file
> 
> Guys, can't we come up with anything better than sched_*_power_saving=n?
> 
> This configuration space is _way_ too large, and now it gets even
> crazier.

Hi Peter and Andreas,

Actually we had sched_power_savings and related simplifications, but
that did not really simplify the interface.

As for this mulit-node MN stuff, Gautham had posted a better solution
to propagate the sched_mc flags without need for new sysfs file and
related changes.

Please take a look at: http://lkml.org/lkml/2009/3/31/137 and
http://lkml.org/lkml/2009/3/31/142 which actually degenerates the
domain.

However Andreas's requirement seem to indicate multiple nodes within
a single socket.  I did not yet completely understand that topology.
Some for of smart degeneration may save an additional tunable here.

Thanks for pointing me to this patch.

--Vaidy
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