Messages in this thread | | | Date | Sat, 23 Feb 2019 19:17:39 +0100 (CET) | From | Thomas Gleixner <> | Subject | Re: [PATCH v12 3/3] Documentation/filesystems/proc.txt: add AVX512_elapsed_ms |
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On Sat, 23 Feb 2019, Thomas Gleixner wrote: > On Thu, 21 Feb 2019, Aubrey Li wrote: > Something like this instead of this conglomorate of useful, irrelevant and > misleading information: > > The AVX512_elapsed_ms entry shows the milliseconds elapsed since the last > time AVX512 usage was recorded. The recording happens on a best effort > basis when a task is scheduled out. This means that the value depends on > two factors: > > 1) The time which the task spent on the CPU without being scheduled > out. With CPU isolation and a single runnable task this can take > several seconds. > > 2) The time since the task was scheduled out last. Depending on the > reason for being scheduled out (time slice exhausted, syscall ...) > this can be arbitrary long time. > > As a consequence the value cannot be considered precise and authoritive > information. The application which uses this information has to be aware > of the overall scenario on the system in order to determine whether a > task is a real AVX512 user or not. > > See? No jiffies, no code snippets, no absolute numbers and no magic > recommendation which might be correct for your test scenario, but > completely bogus for some other scenario. > > Instead it contains the things which a application programmer who wants to > use that value needs to know. He then has to map it to his scenario and > build the crystal ball logic which makes it perhaps useful.
And of course the special value -1 needs to be documented as well....
Thanks,
tglx
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