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Date:   Mon, 5 Sep 2022 18:07:23 +0100
From:   Sudeep Holla <sudeep.holla@arm.com>
To:     Yicong Yang <yangyicong@huawei.com>
Cc:     vincent.guittot@linaro.org, ionela.voinescu@arm.com,
        gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org,
        rafael@kernel.org, 21cnbao@gmail.com, jonathan.cameron@huawei.com,
        linuxarm@huawei.com, prime.zeng@huawei.com,
        yangyicong@hisilicon.com
Subject: Re: [PATCH v3] arch_topology: Make cluster topology span at least
 SMT CPUs
Message-ID: <20220905170723.ppikgcjtjwe2nj63@bogus>
References: <20220905122615.12946-1-yangyicong@huawei.com>
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On Mon, Sep 05, 2022 at 08:26:15PM +0800, Yicong Yang wrote:
> From: Yicong Yang <yangyicong@hisilicon.com>
> 
> Currently cpu_clustergroup_mask() will return CPU mask if cluster span more
> or the same CPUs as cpu_coregroup_mask(). This will result topology borken
> on non-Cluster SMT machines when building with CONFIG_SCHED_CLUSTER=y.
> 
> Test with:
> qemu-system-aarch64 -enable-kvm -machine virt \
>  -net none \
>  -cpu host \
>  -bios ./QEMU_EFI.fd \
>  -m 2G \
>  -smp 48,sockets=2,cores=12,threads=2 \
>  -kernel $Image \
>  -initrd $Rootfs \
>  -nographic
>  -append "rdinit=init console=ttyAMA0 sched_verbose loglevel=8"
> 
> We'll get below error:
> [    3.084568] BUG: arch topology borken
> [    3.084570]      the SMT domain not a subset of the CLS domain
> 
> Since cluster is a level higher than SMT, fix this by making cluster
> spans at least SMT CPUs.
> 
> Cc: Sudeep Holla <sudeep.holla@arm.com>

Sorry for missing to figure this out earlier and thanks for fixing it.
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>

-- 
Regards,
Sudeep