pid start time and new display field in proc pid stat

[jim.cromie at gmail.com]

On Thu, Mar 25, 2021 at 6:53 AM Navin P <navinp0304 at gmail.com> wrote:

> Hi,
>
>  As of 5.11 kernel (pid,pid_start_time) is not unique /monotonic even
> though the underlying counters are .
>  I chose start_boottime because i wanted the counter to increase
> during suspend as well.
>
> 1. Is there any case where task->start_boottime or
> ktime_get_boottime_ns doesn't become monotonic i.e increasing ?
>
> 2.  If start_boottime is not monotonic which counter to use ?
>
> 3.  If i create a new field in task_struct , then i can use a
> atomic_add_return(1,&v) to fill in the task->new_field. Will this also
> work ?
>
>
Its my understanding that task-struct is a highly "contended" resource.

its a basic element, its size matters
everybody wants a bit/byte for something special,
conflicts ensue (or could).
nobody gets them without a real good reason.

I dont know what youre trying to achieve, but i suspect that
youll need to find a more subtle way of doing it.
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