Messages in this thread | | | Date | Fri, 14 Oct 2022 08:37:18 +0800 | From | Feng Tang <> | Subject | Re: [PATCH v2] x86/tsc: Extend watchdog check exemption to 4-Sockets platform |
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On Thu, Oct 13, 2022 at 09:02:43AM -0700, Dave Hansen wrote: > On 10/13/22 06:12, Feng Tang wrote: > > @@ -1217,7 +1217,7 @@ static void __init check_system_tsc_reliable(void) > > if (boot_cpu_has(X86_FEATURE_CONSTANT_TSC) && > > boot_cpu_has(X86_FEATURE_NONSTOP_TSC) && > > boot_cpu_has(X86_FEATURE_TSC_ADJUST) && > > - nr_online_nodes <= 2) > > + nr_online_nodes <= 4) > > tsc_disable_clocksource_watchdog(); > > I still don't think we should perpetuate this hack. > > This just plain doesn't work in numa=off numa=fake=... or presumably in > cases where NUMA is disabled in the firmware and memory is interleaved > across all sockets. > > It also presumably doesn't work on two-socket systems that have > Cluster-on-Die or Sub-NUMA-Clustering where a single socket is chopped > up into multiple nodes.
Yes, after you raised the 'nr_online_nodes' issue, Peter, Rui and I have discussed the problem, and plan to post a RFC patch as in https://lore.kernel.org/lkml/Y0UgeUIJSFNR4mQB@feng-clx/
Which can cover: - numa=fake=... case - platform has DRAM nodes and cpu-less HBM/PMEM nodes
and 'sub-numa-clustering' can't be covered, and the tsc will be watchdoged as before.
For numa=off case, there is only one CPU up, and I think lifting this watchdog for tsc is fine.
Thanks, Feng
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