Messages in this thread | | | Subject | Re: [ANNOUNCE] New utility: 'trace' | From | Peter Zijlstra <> | Date | Wed, 17 Nov 2010 15:18:25 +0100 |
| |
On Wed, 2010-11-17 at 15:11 +0100, Peter Zijlstra wrote: > The idea was to not let the filter engine work on the trace data (once > its gathered) but on the trace argument right at the beginning of the > tracepoint callchain, since some of the trace data is an expression of > the trace argument (say next->prio instead of next), the trace > expression wouldn't stay invariant, you'd have to write a different > filter for the same effect. > > So I think it would be wise to make this change sooner rather than > later.
Also, I see a lot of overlap with the dynamic probes stuff which needs the help of magic dwarves to come up with the right data to gather.
Merging the dynamic tracepoint and filter stuff would be nice, there's no way you can express next->prio without the help of these short buggers with large axes.
The trouble is that the dynamic tracepoint stuff is privileged for good reasons, try next+0x1000000 and you're out in the woods, priv. only filters otoh just doesn't sound too hot.
Another nasty thing is that you actually need to have these dwarves present, which means having the -debug package installed.
| |