Re: [ltt-dev] hybrid mode questions

* Jerry Hom ([email protected]) wrote:
> 
> Hi!  I'm revisiting the issue of hybrid mode.  I've been testing
> recently with kernel 2.6.18.3, LTTng 0.6.33, LTTV 0.8.72.  Since I'm
> mainly interested in process info (which currently seems to be in the
> medium rate channel) and don't need the high rate stuff, I tried
> running in hybrid mode and then stopping without dumping the flight
> recorder buffers.  The advantage with keeping only the medium and low
> rate channel is the much smaller log size.
> 
> However, the problem is that a bunch of process names and pids are
> missing.  The processes seem to be those which start after the initial
> kernel statedump, and they become generically named "swapper".  Also,
> their pids become '0'.  Can this be fixed easily?  Could you please
> point me in the direction to help fix this?
> 

Oh, I guess I have put the exec and compat_exec events in the high rate
channel right ? Should be in medium rate. Those events stamp the process
names.

I will dig into this soon. A patch would be welcome though :)

Mathieu

> On Thu, 14 Sep 2006, Mathieu Desnoyers wrote:
> 
> > * Jerry Hom ([email protected]) wrote:
> > > 
> > > I'm excited about the new hybrid mode, thanks!  It seems to address
> > > what I've been thinking.  Namely, I'm trying to gather a day long
> > > trace (eg, 8 hours), but the file sizes can reach 10GB+.  I have a
> > > question though about the high rate events in the flight recorder
> > > buffer.  Will that buffer always be dumped when the tracing is
> > > stopped?
> > > 
> > 
> > Only is the lttd daemon for reading (only) the flight recorder buffers is
> > spawned before the trace channel are destroyed. In the lttctl sequence of
> > operation I explained in the email earlier, yes, the flight recorder channels
> > are dumped and only then the trace channels are destroyed.
> > 
> > > Actually, for my purposes, I'm much more interested in the low rate
> > > events such as processes.  Perhaps a nice feature would be a toggle
> > > switch to turn on/off the high/medium/low rate events individually?
> > > 
> > 
> > Yes, and eventually, it would be great to multiplex them on the fly per event or
> > per facility. I guess it will eventually come as an extension to the filter
> > kernel module for dynamic event filtering (it's not implemented at all yet).
> > 
> > I'm glad it suits your needs!
> > 
> > Mathieu
> > 
> > 
> > > -- 
> > > Jerry Hom
> > > 
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> 
> -- 
> Jerry Hom
> 
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-- 
Mathieu Desnoyers
Computer Engineering Ph.D. Candidate, Ecole Polytechnique de Montreal
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68