Messages in this thread | | | Date | Fri, 14 Oct 2022 09:14:39 +0800 | From | Feng Tang <> | Subject | Re: [PATCH v2] x86/tsc: Extend watchdog check exemption to 4-Sockets platform |
| |
On Fri, Oct 14, 2022 at 08:37:18AM +0800, Feng Tang wrote: > 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.
Sorry, I was wrong about this. 'numa=off' will still boot all CPUs up, but skip SRAT table init and only show one node. so this is another case that the fix patch can't cover.
Thanks, Feng
| |