Messages in this thread | | | Subject | Re: [PATCH] x86, sched: Allow NUMA nodes to share an LLC on Intel platforms | From | Dave Hansen <> | Date | Wed, 10 Feb 2021 07:22:03 -0800 |
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On 2/10/21 12:05 AM, Peter Zijlstra wrote: >> + if (IS_ENABLED(CONFIG_NUMA)) >> + set_cpu_bug(c, X86_BUG_NUMA_SHARES_LLC); >> } > This seens wrong too, it shouldn't be allowed pre SKX. And ideally only > be allowed when SNC is enabled.
Originally, this just added a few more models to the list of CPUs with SNC. I was hoping for something a bit more durable that we wouldn't have to go back and poke at every year or two.
> Please make this more specific than: all Intel CPUs. Ofcourse, since you > all knew this was an issue, you could've made it discoverable > _somewhere_ :-(
You're totally right, of course. The hardware could enumerate SNC as a feature explicitly somewhere. But, that's a little silly because all of the information that it's enumerating about the CPU caches and NUMA nodes present and correct is *correct*. The secondary information would only be for the CPU to say, "yeah, I'm really sure about that other stuff".
I think this sanity check has outlived its usefulness.
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