Re: [PATCH 0/3] Add walltime support for ring-buffer

Ingo Molnar
2009-08-03T07:23:12Z

* KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> wrote:

> It can. but I don't think it is sufficient. On flight recorder
> use-case, The tracing run more than one year. And, Administrator
> only see last N sec log. (previous logs were overwritten by
> ring-buffer go-around)

That's definitely something we want to enable ASAP.

I'm wondering why a single u64 timestamp is not enough to express
the full, absolute range of time elapsed since bootup, in
nanoseconds.

That would make walltime a matter of pretty-printing only - we'd
have to convert the u64 nsec timestamp into a walltime format,
right?

In fact we could change all the timestamps to be standardized along
'nanoseconds elapsed since 1970' or so - not nanoseconds since the
last bootup. That still fits just fine within 64 bits - u64
nanoseconds has a scope of 500+ years.

Ingo