linux-kernel - Re: [PATCH 2/6] sched: add a new SD SHARE_POWERLINE flag for sched

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Date:	Thu, 13 Dec 2012 10:24:00 +0800
From:	Alex Shi <alex.shi@...el.com>
To:	Vincent Guittot <vincent.guittot@...aro.org>
CC:	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linaro-dev@...ts.linaro.org, peterz@...radead.org,
	mingo@...nel.org, linux@....linux.org.uk, pjt@...gle.com,
	santosh.shilimkar@...com, Morten.Rasmussen@....com,
	chander.kashyap@...aro.org, cmetcalf@...era.com,
	tony.luck@...el.com, preeti@...ux.vnet.ibm.com,
	paulmck@...ux.vnet.ibm.com, tglx@...utronix.de,
	len.brown@...el.com, arjan@...ux.intel.com,
	amit.kucheria@...aro.org, viresh.kumar@...aro.org
Subject: Re: [PATCH 2/6] sched: add a new SD SHARE_POWERLINE flag for sched_domain

On 12/12/2012 09:31 PM, Vincent Guittot wrote:
> This new flag SD_SHARE_POWERDOMAIN is used to reflect whether groups of CPU in
> a sched_domain level can or not reach a different power state. If clusters can
> be power gated independently, as an example, the flag should be cleared at CPU
> level. This information is used to decide if it's worth packing some tasks in
> a group of CPUs in order to power gated the other groups instead of spreading
> the tasks. The default behavior of the scheduler is to spread tasks so the
> flag is set into all sched_domains
> 
> Signed-off-by: Vincent Guittot <vincent.guittot@...aro.org>
> ---
>  arch/ia64/include/asm/topology.h |    1 +
>  arch/tile/include/asm/topology.h |    1 +
>  include/linux/sched.h            |    1 +
>  include/linux/topology.h         |    4 ++++
>  kernel/sched/core.c              |    6 ++++++
>  5 files changed, 13 insertions(+)
> 
> diff --git a/arch/ia64/include/asm/topology.h b/arch/ia64/include/asm/topology.h
> index a2496e4..6d0b617 100644
> --- a/arch/ia64/include/asm/topology.h
> +++ b/arch/ia64/include/asm/topology.h
> @@ -65,6 +65,7 @@ void build_cpu_to_node_map(void);
>  				| SD_BALANCE_EXEC	\
>  				| SD_BALANCE_FORK	\
>  				| SD_WAKE_AFFINE,	\
> +				| arch_sd_local_flags(0)\
>  	.last_balance		= jiffies,		\
>  	.balance_interval	= 1,			\
>  	.nr_balance_failed	= 0,			\
> diff --git a/arch/tile/include/asm/topology.h b/arch/tile/include/asm/topology.h
> index d5e86c9..adc8710 100644
> --- a/arch/tile/include/asm/topology.h
> +++ b/arch/tile/include/asm/topology.h
> @@ -71,6 +71,7 @@ static inline const struct cpumask *cpumask_of_node(int node)
>  				| 0*SD_WAKE_AFFINE			\
>  				| 0*SD_SHARE_CPUPOWER			\
>  				| 0*SD_SHARE_PKG_RESOURCES		\
> +				| arch_sd_local_flags(0)		\
>  				| 0*SD_SERIALIZE			\
>  				,					\
>  	.last_balance		= jiffies,				\
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index 046e39a..3287be1 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -844,6 +844,7 @@ enum cpu_idle_type {
>  #define SD_BALANCE_WAKE		0x0010  /* Balance on wakeup */
>  #define SD_WAKE_AFFINE		0x0020	/* Wake task to waking CPU */
>  #define SD_SHARE_CPUPOWER	0x0080	/* Domain members share cpu power */
> +#define SD_SHARE_POWERDOMAIN	0x0100	/* Domain members share power domain */
>  #define SD_SHARE_PKG_RESOURCES	0x0200	/* Domain members share cpu pkg resources */
>  #define SD_SERIALIZE		0x0400	/* Only a single load balancing instance */
>  #define SD_ASYM_PACKING		0x0800  /* Place busy groups earlier in the domain */
> diff --git a/include/linux/topology.h b/include/linux/topology.h
> index d3cf0d6..3eab293 100644
> --- a/include/linux/topology.h
> +++ b/include/linux/topology.h
> @@ -99,6 +99,8 @@ int arch_update_cpu_topology(void);
>  				| 1*SD_WAKE_AFFINE			\
>  				| 1*SD_SHARE_CPUPOWER			\
>  				| 1*SD_SHARE_PKG_RESOURCES		\
> +				| arch_sd_local_flags(SD_SHARE_CPUPOWER|\
> +						SD_SHARE_PKG_RESOURCES) \
>  				| 0*SD_SERIALIZE			\
>  				| 0*SD_PREFER_SIBLING			\
>  				| arch_sd_sibling_asym_packing()	\
> @@ -131,6 +133,7 @@ int arch_update_cpu_topology(void);
>  				| 1*SD_WAKE_AFFINE			\
>  				| 0*SD_SHARE_CPUPOWER			\
>  				| 1*SD_SHARE_PKG_RESOURCES		\
> +				| arch_sd_local_flags(SD_SHARE_PKG_RESOURCES)\
>  				| 0*SD_SERIALIZE			\
>  				,					\
>  	.last_balance		= jiffies,				\
> @@ -161,6 +164,7 @@ int arch_update_cpu_topology(void);
>  				| 1*SD_WAKE_AFFINE			\
>  				| 0*SD_SHARE_CPUPOWER			\
>  				| 0*SD_SHARE_PKG_RESOURCES		\
> +				| arch_sd_local_flags(0)		\

The general style looks like prefering SD_XXX flag directly.

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