[ltt-dev] [RFC] Common Trace Format Requirements (v1.3)

[Michel Dagenais]

> I have been hoping that as a part of this standard that we will end up
> with common schemas for meta-data that are shared by various use cases,
> so that things that are common concepts to many OS'es for example could
> in fact be shared and thus you could have a trace analyzer that works
> for OS'es that have similar models and generate data in a compatible
> schema.  In practice this may be difficult, but it seems like a noble
> goal to aim for.  If we can get a fixed schema for the fundamental types
> that will be a step in the right direction.

The event related to "scheduling change" may still differ quite a bit 
from one OS to the other. We have been thinking about that and the 
notion of "synthetic event" may act as an interface layer in the 
analysis tool. A trace on Linux has sched_change events in its own way, 
and a BSD system may have something somewhat different. A plugin in the 
trace analysis system specific to Linux traces would generate from the 
"sched_change" event two synthetic events "process p1 stopped running on 
cpu 0" and "process p2 started running on cpu 0". Similarly, a BSD 
plugin in the trace visualizer would generate similar synthetic events 
from the BSD specific scheduling event.

Thus, it could be useful to have some base events identical between OSes 
but it may not be a strong requirement after all.