Messages in this thread | | | Date | Thu, 24 Feb 2022 09:24:11 +0100 | Subject | Re: [PATCH 2/2] torture: Make thread detection more robust by using lspcu | From | Paul Menzel <> |
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Dear Paul,
Am 22.02.22 um 18:43 schrieb Paul E. McKenney: > 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@molgen.mpg.de> > > 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?
You are right. I guess with 1/2 I just wanted to document clearly, what I learned in #sed@irc.libera.chat, that means, how to avoid using grep, when sed is used.
Kind regards,
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 >>
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