Re: LTTng kernel integration roadmap, update

[Lai Jiangshan <laijs@cn.fujitsu.com>]

Mathieu Desnoyers wrote:

> - Marker ID management
>   Background :
>   The markers are currently used to identify the numerical event IDs
>   associated with a named event as well as the event types (format
>   string) associated with that event. Those two informations are kept in
>   a table written in the metadata channel. A "channel" could be thought
>   as being a set of per-cpu buffers, where information transits. This
>   information would typically be related to a specific tracer. Note,
>   however, that the information generated by a tracer should always be
>   parseable generically and be transformable into text output by a
>   simple parser, because we want to permit analysis across information
>   logged by the various tracer.
> 
>   Action item :
>   The current event IDs are global to the whole kernel. It would be
>   beneficial to change their scope so they are per-channel instead,
>   because we can then encode most events in the low-order bits of the
>   event ID bits, therefore keeping events as small as possible.
> 

Hi, Mathieu Desnoyers:

It also required by ASCII text output.

ASCII text output needs get name&fmt from eID, but In current code,
I cannot find a reliable way to get name&fmt from eID. And also,
in the kernel space, we must get name&fmt from eID as fast as possible
by reason of performance. So I cannot use metadata channel for it.

When "Add periodical subbuffer flush for streaming" and "Marker ID management"
will done?

Thanks, Lai.