Re: [RFC PATCH 1/3] Unified trace buffer

[Jeremy Fitzhardinge <jeremy@goop.org>]

Linus Torvalds wrote:
> As for C2/C3 - that's just an argument for *not* doing anything at trace 
> time. What do you think happens when you try to trace through those 
> things? You're much better off trying to sort out the problems later, when 
> you don't hold critical locks and are possibly deep down in some buggy 
> ACPI code, and you're trying to trace it exactly _because_ it is buggy.
>   

That suggests that frequency changes should be recorded at a lower layer
as well, along with full timestamps and deltas, so that a log parser can
correctly generate the timestamps without having to parse higher-level
trace records.  Maybe the simplest thing to do is make the full
timestamp records also include frequency and offset information (to deal
with discontinuities caused by things like a vcpu switching between
physical cpus with unsynced tscs).

    J