On Wed, Oct 03, 2012 at 03:36:53PM -0400, Dave Jones wrote: > On Wed, Oct 03, 2012 at 07:46:18PM +0200, Frederic Weisbecker wrote: > > > it in the kernel tree, unless we wanted people to use the option? > > > > A solution could be to add that option under CONFIG_DEBUG_KERNEL and > specify > > that it must only be enabled by developers for specific reasons (overhead, > > security). CONFIG_PROVE_LOCKING falls into that category, right? > > > > We have CONFIG_RCU_USER_QS that is a specific case. It's an intermediate > state > > before we implement a true CONFIG_NO_HZ_FULL. But the option is useless on > its > > own for users. Worse, it introduces a real overhead. OTOH we want it to be > upstream > > to make the development of full tickless feature more incremental. > > > > Perhaps we should put that under CONFIG_DEBUG_KERNEL. > > Overloading an existing config option for something unrelated seems > unpleasant to me. > It will only take a few people to start doing this, before it turns into a > landslide > where everyone ends up with DEBUG_KERNEL set. > And what of people who already have DEBUG_KERNEL set ?
Sorry, by wording wasn't clear. I didn't mean overloading CONFIG_DEBUG_KERNEL but rather depend on it. > > Just state what you wrote above in the kconfig. > Currently, RCU_USER_QS says nothing about the fact that it's work in progress. Yeah I much prefer that. I'll add some details on the Kconfig. > The missing part that I don't have an answer for however, is what happens > when you deem this production ready? Distro maintainers won't notice the > kconfig text changing. But perhaps that's a good thing, and will lead to > things > only being enabled when people explicitly ask for them in distros. That Kconfig option is likely going to disappear inside a new CONFIG_NO_HZ_FULL that will enables individual features like RCU user mode and stuffs. And if it stays, it will be enabled by CONFIG_NO_HZ_FULL. So it's not an option anybody will ever have to deal with directly. > Alternatively, if you really do want to go the path of a new config option, > perhaps CONFIG_NOT_DISTRO_READY would spell things out more clearly. > EXPERIMENTAL is such a wasteland it would take too much manpower to audit > every case, and update accordingly, but scorching the earth and starting > afresh might be feasible. CONFIG_STAGING already does that kind of thing I guess. Although I suspect people are reluctant with core features in -staging. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
