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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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