Re: [RFC PATCH] LTTng relay buffer allocation, read, write

Martin Bligh
2008-09-30T20:50:10Z

> I am not saying anything about the actual number of events with 0 bytes
> payload I actually have in my own instrumentation, if this is what you
> mean. I am just saying that it leaves this room available for such
> events.

It would, yes. Are they useful?

> Even if there is a 32 bits payload associated with those events, the
> fact that we can encode the event ID in the 32 bits header will bring
> those events from 96 bits (due to 32 bits alignment) down to 64 bits.

That's true. So do we have a bunch of stuff that we really really need
that'd fit into 32 bits, but not 28 bits?

>> This is all over 1 bit of information, right? Since you need at least 1 for
>> the timestamp stuff.
>
> 4 bits of information could be added to the 32-bits header if we allow
> tracers to register their first 15 event IDs in those 4 bits.
>
> But well... let's keep that for v2. ;)

Sounds like a plan ;-) All this stuff is internal representations anyway.