Messages in this thread | | | Date | Tue, 30 Sep 2008 14:14:36 -0400 | From | Mathieu Desnoyers <> | Subject | Re: [RFC PATCH] LTTng relay buffer allocation, read, write |
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* Martin Bligh (mbligh@google.com) wrote: > On Tue, Sep 30, 2008 at 10:22 AM, Martin Bligh <mbligh@google.com> wrote: > >> A 4 byte dataless payload is useless anyway. > > > > Not at all convinced that's true - we used it for lots of things. > > Start and end of irq event is one frequent example. > > > > Also, in a compact mode, we can record start and end of > > syscalls like this (without parameters). > > Ah, sorry, maybe I misread this. No data with no event ids, etc > is fairly useless. 4 bytes data including space to record event ids is OK.
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.
Mathieu
-- Mathieu Desnoyers OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
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