Re: [PATCH v6 1/3] x86/fpu: track AVX-512 usage of tasks

Andi Kleen
2018-12-18T21:38:29Z

> I misunderstood, you mean 32bit kernel, not 32bit machine. Theoretically 32bit
> kernel can use AVX512, but not sure if anyone use it like this. get_jiffies_64()
> includes jiffies_lock ops so not good in context switch. So I want to use raw
> jiffies_64 here. jiffies is a good candidate but it has wraparound overflow issue.
> Other time source are expensive here.
>
> Should I limit the code only running on 64bit kernel?

Yes making it 64bit only should be fine.

Other alternative would be to use 32bit jiffies on 32bit. I assume
wrapping is not that big a problem here.

-Andi