> On Fri, Apr 30, 2010 at 12:16:45PM -0400,
Valdis.Kletnieks@vt.edu wrote:
> > On Fri, 30 Apr 2010 11:33:34 EDT, Mathieu Desnoyers said:
> >
> > > I recommend creating a kernel command line parameter that would tweak
> > > the number of messages printed by lockdep. The default would indeed by 1
> > > message, but people in a debugging marathon can specify a larger value
> > > so they won't have to reboot between each individual lockdep error.
> >
> > Yeah, that would rock for development kernels - playing whack-a-mole with
> > a half-dozen new lockdep whinges can easily stretch out for quite some time.
>
> The RCU-lockdep splats are a bit different in nature than the
> deadlock-related splats that lockdep normally prints. The RCU-lockdep
> splats are transient in nature, and it is easy to apply WARN_ON_ONCE().
> In contrast, if you permit multiple deadlock-related lockdep splats,
> you tend to get lots of warnings about the same deadlock cycle.
>
> So how about an additional kernel configuration variable, default
> disabled, perhaps named CONFIG_PROVE_RCU_MULTIPLE, that allows a
> single boot to see multiple messages? Unlike the dyntick-idle
> WARN_ON()s that generated multi-gigabyte console logs in a great
> hurry, I haven't yet seen excessive quantities of RCU-lockdep splats,
> so I don't see the need for an integer limit.
>
> Thoughts?
