On Tue, Feb 22, 2022 at 01:07:17PM +0100, Paul Menzel wrote:
> For consecutive numbers *lscpu* collapses the output and just shows the
> range with start and end. The processors are numbered that way on POWER8.
>
> $ sudo ppc64_cpu --smt=8
> $ lscpu | grep '^NUMA node'
> NUMA node(s): 2
> NUMA node0 CPU(s): 0-79
> NUMA node8 CPU(s): 80-159
>
> This causes the heuristic to detect the number threads per core, looking
> for the number after the first comma, to fail, and QEMU aborts because of
> invalid arguments.
>
> $ lscpu | sed -n -e '/^NUMA node0/s/^[^,]*,\([0-9]*\),.*$/\1/p'
> $
>
> (Before the last patch, the whole line was returned.)
>
> $ lscpu | grep '^NUMA node0' | sed -e 's/^[^,-]*(,|\-)\([0-9]*\),.*$/\1/'
> NUMA node0 CPU(s): 0-79
>
> *lscpu* shows the number of threads per core, so use that value directly.
>
> $ sudo ppc64_cpu --smt=8
> $ lscpu | grep 'Thread(s) per core'
> Thread(s) per core: 8
> $ sudo ppc64_cpu --smt=off
> $ lscpu | grep 'Thread(s) per core'
> Thread(s) per core: 1
>
> Note, the replaced heuristic is also incorrect for that case, where the
> threads per core are disabled.
>
> $ lscpu | sed -n -e '/^NUMA node0/s/^[^,]*,\([0-9]*\),.*$/\1/p'
> 8
>
> Signed-off-by: Paul Menzel <pmenzel@xxxxxxxxxxxxx>
Makes sense, and thank you for chasing this down and for the fix!
But should this patch and 1/2 be merged? Or am I confused and they
are somehow affecting two different lines of scripting?
Thanx, Paul
> ---
> tools/testing/selftests/rcutorture/bin/functions.sh | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tools/testing/selftests/rcutorture/bin/functions.sh b/tools/testing/selftests/rcutorture/bin/functions.sh
> index 5cff520955e6..66d0414d8e4b 100644
> --- a/tools/testing/selftests/rcutorture/bin/functions.sh
> +++ b/tools/testing/selftests/rcutorture/bin/functions.sh
> @@ -301,7 +301,7 @@ specify_qemu_cpus () {
> echo $2 -smp $3
> ;;
> qemu-system-ppc64)
> - nt="`lscpu | sed -n -e '/^NUMA node0/s/^[^,]*,\([0-9]*\),.*$/\1/p'`"
> + nt="`lscpu | sed -n 's/^Thread(s) per core:\s*//p'`"
> echo $2 -smp cores=`expr \( $3 + $nt - 1 \) / $nt`,threads=$nt
> ;;
> esac
> --
> 2.35.1
>
