Messages in this thread | | | Date | Tue, 5 Jul 2022 21:07:37 +0100 | From | Sudeep Holla <> | Subject | Re: [PATCH v6 00/21] arch_topology: Updates to add socket support and fix cluster ids |
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On Tue, Jul 05, 2022 at 07:06:17PM +0000, Conor.Dooley@microchip.com wrote: > [Adding back the CC list from the original thread] > > On 05/07/2022 13:27, Brice Goglin wrote: > > [You don't often get email from brice.goglin@inria.fr. Learn why this is important at https://aka.ms/LearnAboutSenderIdentification ] > > > > EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe > > > > Hello Conor > > > > I am the main developer of hwloc [1] which is used by many people to > > detect the topology of servers. We're started to see some users of hwloc > > on RISC-V and we got some reports about the topology exposed by > > Linux/sysfs being wrong on some platforms. > > > > For instance https://github.com/open-mpi/hwloc/issues/536 says HiFive > > Unmatched with SiFive Freedom U740 running Linux 5.15 exposes a single > > core with 4 threads instead of 4 cores, while StarFive VisionFive v1 > > with JH7100 running 5.18.5 correctly exposes 2 cores. > > And with Sudeep's patches applied I get (next-20220704): > # hwloc-calc -N core all > 1 > # hwloc-calc -N pu all > 4 > On a PolarFire SoC (so the same as a SiFive U540). > So unfortunately, these patches are not the fix you seek! >
Not sure what you mean by that ?
> Wracked my brains for a bit, but could not see any differences > between the U740 and the JH7100. Culprit seems to be the lack > of a cpu-map node (which is only present in the downstream dt). >
Indeed, the topology depends on /cpu-map node. However on ARM64 we do have fallback settings in absence of /cpu-map node so that it is handled correctly. I wasn't sure what was or can be done on RISC-V as /cpu-map is optional.
> I've sent patches for the upstream devicetrees: > https://lore.kernel.org/linux-riscv/20220705190435.1790466-1-mail@conchuod.ie/ >
I will take a look.
> > Does it depend a lot on the platform because > > device-tree and/or ACPI aren't always properly filled by vendors?
Absolutely.
> > Does it depend a lot on the Linux kernel version?
Ideally not much, but hey we had some issues on Arm64 too which this series is addressing.
> > Should I expect significant improvements for both in the next months?
Not much in topology or nothing planned. I have no idea on NUMA
Hi Conor,
I would have preferred you to add me to the original thread and referred this thread from there. I don't want to derail the discussion in this thread as nothing much can be done here.
-- Regards, Sudeep
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