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

From: Li, Aubrey
Date: Tue Dec 18 2018 - 19:26:35 EST

On 2018/12/19 5:38, Andi Kleen wrote:
>> 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.

Thomas, is this acceptable?