Messages in this thread | | | Date | Tue, 30 Sep 2008 14:35:31 -0400 | From | Mathieu Desnoyers <> | Subject | Re: [RFC PATCH] LTTng relay buffer allocation, read, write |
| |
* Steven Rostedt (rostedt@goodmis.org) wrote: > > On Tue, 30 Sep 2008, Mathieu Desnoyers wrote: > > > > In Steven's scheme, the event IDs in the 4 bytes are reserved for > > (useless) internal use ;) They can therefore not be used for specific > > tracer event IDs, which I think is a misuse of the precious bits > > otherwise available to store really useful event IDs. > > I'm using them, so they must not be totally useless. ;-) > > But ftrace has its own event ids and I don't want the ring buffer to ever > have to know about them. > > -- Steve >
You are actually using them to put redundant information that could be encoded differently and thus save 4 bits per event records, more or less what will be needed by most tracers (15 IDs, 1 reserved for an extended ID field).
So the fact that you use them does not mean they are really required, and I don't think such duplicated information actually makes things more solid. Maybe just more obscure ?
Mathieu
-- Mathieu Desnoyers OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
| |