linux-kernel - Re: [PATCH 0/4] sched/topology: Set SD_ASYM

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Message-ID: <20180731105349.GQ2476@hirez.programming.kicks-ass.net>
Date:   Tue, 31 Jul 2018 12:53:49 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Morten Rasmussen <morten.rasmussen@....com>
Cc:     mingo@...hat.com, valentin.schneider@....com,
        dietmar.eggemann@....com, vincent.guittot@...aro.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 0/4] sched/topology: Set SD_ASYM_CPUCAPACITY flag
 automatically

On Fri, Jul 20, 2018 at 02:32:30PM +0100, Morten Rasmussen wrote:
> The SD_ASYM_CPUCAPACITY flag has been around for some time now with no code to
> actually set it. Android has carried patches to do this out-of-tree in the
> meantime. The flag is meant to indicate cpu capacity asymmetry and is set at
> the topology level where the sched_domain spans all available cpu capacity in
> the system, i.e. all core types are visible, for any cpu in the system.
> 
> The flag was merged as being a topology flag meaning that architecture had to
> provide the flag explicitly, however when mixed with cpusets splitting the
> system into multiple root_domains the flag can't be set without knowledge about
> the cpusets. Rather than exposing cpusets to architecture code this patch set
> moves the responsibility for setting the flag to generic topology code which is
> simpler and make the code architecture agnostic.
> 
> Morten Rasmussen (4):
>   sched/topology: SD_ASYM_CPUCAPACITY flag detection
>   drivers/base/arch_topology: Rebuild sched_domain hierarchy when
>     capacities change
>   arch/arm64: Rebuild sched_domain hierarchy when cpu capacity changes
>   arch/arm: Rebuild sched_domain hierarchy when cpu capacity changes
> 
>  arch/arm/include/asm/topology.h   |  3 ++
>  arch/arm64/include/asm/topology.h |  3 ++
>  drivers/base/arch_topology.c      | 26 +++++++++++++
>  include/linux/arch_topology.h     |  1 +
>  include/linux/sched/topology.h    |  2 +-
>  kernel/sched/topology.c           | 81 ++++++++++++++++++++++++++++++++++++---
>  6 files changed, 109 insertions(+), 7 deletions(-)

I've picked up the lot; Thanks!