Messages in this thread Patch in this message | | | Subject | Re: [PATCH] cpu-topology: warn if NUMA configurations conflicts with lower layer | From | Dietmar Eggemann <> | Date | Mon, 13 Jan 2020 13:22:17 +0100 |
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On 13.01.20 13:08, Zengtao (B) wrote: >> -----Original Message----- >> From: Valentin Schneider [mailto:valentin.schneider@arm.com] >> Sent: Monday, January 13, 2020 7:17 PM >> To: Zengtao (B); Morten Rasmussen >> Cc: Sudeep Holla; Linuxarm; Greg Kroah-Hartman; Rafael J. Wysocki; >> linux-kernel@vger.kernel.org >> Subject: Re: [PATCH] cpu-topology: warn if NUMA configurations >> conflicts with lower layer >> >> On 13/01/2020 06:51, Zengtao (B) wrote: >>> I have tried both, this previous one don't work. But this one seems >> work >>> correctly with the warning message printout as expected. >>> >> >> Thanks for trying it out. >> >>> This patch is based on the fact " non-NUMA spans shouldn't overlap ", >> I am >>> not quite sure if this is always true? >>> >> >> I think this is required for get_group() to work properly. Otherwise, >> successive get_group() calls may override (and break) the sd->groups >> linking as you initially reported. >> >> In your example, for MC level we have >> >> tl->mask(3) == 3-7 >> tl->mask(4) == 4-7 >> >> Which partially overlaps, causing the relinking of '7->3' to '7->4'. Valid >> configurations would be >> >> wholly disjoint: >> tl->mask(3) == 0-3 >> tl->maks(4) == 4-7 >> >> equal: >> tl->mask(3) == 3-7 >> tl->mask(4) == 3-7 >> >>> Anyway, Could you help to raise the new patch? >>> >> >> Ideally I'd like to be able to reproduce this locally first (TBH I'd like >> to get my first suggestion to work since it's less intrusive). Could you >> share how you were able to trigger this? Dietmar's been trying to >> reproduce >> this with qemu but I don't think he's there just yet. > > Do you have got a hardware platform with clusters?what's the hardware > Cpu topology?
I can test this with:
sudo qemu-system-aarch64 -kernel ./Image -hda ./qemu-image-aarch64.img -append 'root=/dev/vda console=ttyAMA0 loglevel=8 sched_debug' -smp cores=8 --nographic -m 512 -cpu cortex-a53 -machine virt -numa node,cpus=0-2,nodeid=0 -numa node,cpus=3-7,nodeid=1
and
diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c index 1eb81f113786..e941a402e5f1 100644 --- a/drivers/base/arch_topology.c +++ b/drivers/base/arch_topology.c @@ -465,6 +465,9 @@ void update_siblings_masks(unsigned int cpuid) if (cpuid_topo->package_id != cpu_topo->package_id) continue;
+ if ((cpu < 4 && cpuid > 3) || (cpu > 3 && cpuid < 4)) + continue; + cpumask_set_cpu(cpuid, &cpu_topo->core_sibling); cpumask_set_cpu(cpu, &cpuid_topo->core_sibling);
on mainline qemu. I do need the hack in update_siblings_masks() since the topology detection via -smp cores=X, sockets=Y doesn't work yet.
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