Re: [RFC PATCH 1/2] Marker probes in futex.c

["K. Prasad" <prasad@linux.vnet.ibm.com>]

On Tue, Apr 15, 2008 at 04:50:09PM +0400, Alexey Dobriyan wrote:
> On Tue, Apr 15, 2008 at 08:32:34AM -0400, Mathieu Desnoyers wrote:
> > * Peter Zijlstra (a.p.zijlstra@chello.nl) wrote:
> > > On Tue, 2008-04-15 at 17:23 +0530, K. Prasad wrote:
> > > 
> > > > +	trace_mark(futex_wait_called, "uaddr:%p fshared:%p val:%u "
> > > > +			"abs_time:%p bitset:%d",
> > > > +			uaddr, fshared, val, abs_time, bitset);
> > > 
> > > This is some seriuosly ugly looking gunk, why would we want stuff like
> > > that scattered across the code?
> > > 
> > 
> > I don't really see how it differs so much from printks, which kernel
> > developers are already familiar with.
> 
> They aren't in every -E codepath, nor they are at the start
> and at the end of every important function (like system call).
> 
> Such printks are usually inserted during debugging when you don't care
> about ugliness and these patches will eventually make kernel looks like
> being permanently debugged one.
>
Wondering how useful would printks be when debugging large systems (say
analysing futex contention on a 32-way CPU system)....also to mention
the inability to do a binary dump of the interested data structures.

--K.Prasad