lkml.org 
[lkml]   [2022]   [Sep]   [3]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v2] arch_topology: Make cluster topology span at least SMT CPUs
On Thu, Aug 25, 2022 at 05:20:07PM +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>
> Cc: Vincent Guittot <vincent.guittot@linaro.org>
> Cc: Ionela Voinescu <ionela.voinescu@arm.com>
> Fixes: bfcc4397435d ("arch_topology: Limit span of cpu_clustergroup_mask()")
> Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
> Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
> Reviewed-by: Ionela Voinescu <ionela.voinescu@arm.com>
> ---
> Change since v1:
> - mention the kernel config CONFIG_SCHED_CLUSTER=y, per Ionela
> Link:https://lore.kernel.org/lkml/20220823073044.58697-1-yangyicong@huawei.com/
>
> drivers/base/arch_topology.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c
> index 0424b59b695e..0056a1273275 100644
> --- a/drivers/base/arch_topology.c
> +++ b/drivers/base/arch_topology.c
> @@ -724,7 +724,7 @@ const struct cpumask *cpu_clustergroup_mask(int cpu)
> */
> if (cpumask_subset(cpu_coregroup_mask(cpu),
> &cpu_topology[cpu].cluster_sibling))
> - return get_cpu_mask(cpu);
> + return cpu_smt_mask(cpu);

As the kernel-test robot reported, this breaks the build on some
architectures, so I'll go and revert it from my tree now.

thanks,

greg k-h

\
 
 \ /
  Last update: 2022-09-03 09:08    [W:0.051 / U:0.376 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site