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SubjectRe: [PATCH 9/15] sched: Check sched_mn_power_savings when setting flags for CPU and MN domains
On Thu, Aug 20, 2009 at 03:40:13PM +0200, Andreas Herrmann wrote:
>
> Use new function sd_balance_for_mn_power() and adapt
> sd_balance_for_package_power() and sd_power_saving_flags() for correct
> setting of flags SD_POWERSAVINGS_BALANCE and SD_BALANCE_NEWIDLE in CPU
> and MN domains.
>
> Furthermore add flag SD_SHARE_PKG_RESOURCES to MN domain.
> Rational: a multi-node processor most likely shares package resources
> (on Magny-Cours the package constitues a "voltage domain").
>
> Signed-off-by: Andreas Herrmann <andreas.herrmann3@amd.com>
> ---
> arch/x86/include/asm/topology.h | 3 ++-
> include/linux/sched.h | 14 ++++++++++++--
> 2 files changed, 14 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/include/asm/topology.h b/arch/x86/include/asm/topology.h
> index 6d7d133..4a520b8 100644
> --- a/arch/x86/include/asm/topology.h
> +++ b/arch/x86/include/asm/topology.h
> @@ -198,7 +198,8 @@ static inline void setup_node_to_cpumask_map(void) { }
> | SD_BALANCE_EXEC \
> | SD_WAKE_AFFINE \
> | SD_WAKE_BALANCE \
> - | sd_balance_for_package_power()\
> + | SD_SHARE_PKG_RESOURCES\
> + | sd_balance_for_mn_power()\
> | sd_power_saving_flags(),\
> .last_balance = jiffies, \
> .balance_interval = 1, \
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index 5755643..c53bdd8 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -844,9 +844,18 @@ static inline int sd_balance_for_mc_power(void)
> return 0;
> }
>
> +static inline int sd_balance_for_mn_power(void)
> +{
> + if (sched_mc_power_savings || sched_smt_power_savings)
> + return SD_POWERSAVINGS_BALANCE;
> +
> + return 0;

This again implies that if SD_POWERSAVINGS_BALANCE is set at any level,
it must also be set at it's parent.

With this constraint, there can only be 4 combinations.
0) SD_POWERSAVINGS_BALANCE not set.
1) SD_POWERSAVINGS_BALANCE set at SD_LV_CPU.
2) SD_POWERSAVINGS_BALANCE set at SD_LV_MN and SD_LV_CPU
3) SD_POWERSAVINGS_BALANCE set at SD_LV_MC, SD_LV_MN and SD_LV_CPU.

If we could independently decide the aggressiveness of consolidation
(i.e, 1 or 2), We can do away with these multiple sysfs variables have
have a single tunable.

Does this make sense ?

> +
> static inline int sd_balance_for_package_power(void)
> {
> - if (sched_mc_power_savings | sched_smt_power_savings)
> + if (sched_mn_power_savings || sched_mc_power_savings ||
> + sched_smt_power_savings)
> return SD_POWERSAVINGS_BALANCE;
>
> return 0;
> @@ -860,7 +869,8 @@ static inline int sd_balance_for_package_power(void)
>
> static inline int sd_power_saving_flags(void)
> {
> - if (sched_mc_power_savings | sched_smt_power_savings)
> + if (sched_mn_power_savings || sched_mc_power_savings ||
> + sched_smt_power_savings)
> return SD_BALANCE_NEWIDLE;
>
> return 0;
> --
> 1.6.0.4
>
>
>
> --
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--
Thanks and Regards
gautham


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