linux-kernel - RE: [PATCH] sched: Enable arch-specific asym packing option in sched domain

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Message-ID: <1DD7BFEDD3147247B1355BEFEFE46652379C3DF102@HQMAIL04.nvidia.com>
Date:	Fri, 4 May 2012 15:18:04 -0700
From:	Diwakar Tundlam <dtundlam@...dia.com>
To:	'Peter Zijlstra' <a.p.zijlstra@...llo.nl>
CC:	'Ingo Molnar' <mingo@...nel.org>,
	'Andrew Morton' <akpm@...ux-foundation.org>,
	'Christoph Lameter' <cl@...two.org>,
	'Michael Neuling' <mikey@...ling.org>,
	'Stephen Rothwell' <sfr@...b.auug.org.au>,
	'Benjamin Herrenschmidt' <benh@...nel.crashing.org>,
	'David Rientjes' <rientjes@...gle.com>,
	"'linux-kernel@...r.kernel.org'" <linux-kernel@...r.kernel.org>,
	Peter De Schrijver <pdeschrijver@...dia.com>
Subject: RE: [PATCH] sched: Enable arch-specific asym packing option in
 sched domain

>> A repost doesn't make it right to add sibling (SMT) properties to a package/socket and will still upset Power7.

Agreed. I only fixed the whitespace and commitId.

arch_sd_sibling_asym_packing() is already present under ifdef CONFIG_SMT.
I didn't touch that. I only added it to SD_CPU_INIT for all cpu's.
I assumed Power7 shouldn't use SD_CPU_INIT.

I don't understand Power7 arch to comment on impact.
Michael Neuling should review this carefully and advise.

Maybe I should define a separate weak symbol, say arch_sd_bias_to_lower_num_cpu()?
Then Power7 can define arch_sd_sibling_asym_packing() to be '1' and it will not
break all-cpu init.

We need this for Tegra's slight asymmetry with core0.

Thanks,
--Diwakar.

-----Original Message-----
From: Peter Zijlstra [mailto:a.p.zijlstra@...llo.nl] 
Sent: Friday, May 04, 2012 3:10 PM
To: Diwakar Tundlam
Cc: 'Ingo Molnar'; 'Andrew Morton'; 'Christoph Lameter'; 'Michael Neuling'; 'Stephen Rothwell'; 'Benjamin Herrenschmidt'; 'David Rientjes'; 'linux-kernel@...r.kernel.org'; Peter De Schrijver
Subject: RE: [PATCH] sched: Enable arch-specific asym packing option in sched domain

On Fri, 2012-05-04 at 15:06 -0700, Diwakar Tundlam wrote:
> +                               | arch_sd_sibling_asym_packing()        \
>                                 | sd_balance_for_package_power()        \
>                                 | sd_power_saving_flags()               \
>                                 ,                                       \ 

A repost doesn't make it right to add sibling (SMT) properties to a package/socket and will still upset Power7.
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