Re: [PATCH V2 3/3] sched/deadline: Tracepoints for deadline scheduler

[Steven Rostedt]

On Tue, 29 Mar 2016 22:11:45 +0200
Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:


> > Yes, we don't want to get rid of the old one. But it shouldn't break
> > anything if we extend it. I'm thinking of extending it with a dynamic
> > array to store the deadline task values (runtime, period). And for non
> > deadline tasks, the array would be empty (size zero). I think that
> > could be doable and maintain backward compatibility.  
> 
> Why the complexity? Why not just tack those 32 bytes on and get on with
> life?

32 bytes that are zero and meaningless for 99.999% of scheduling?

The scheduling tracepoint is probably the most common tracepoint used,
and one of the frequent ones. 32bytes of wasted space per event can
cause a lot of tracing to be missed.

-- Steve