Messages in this thread | | | Date | Mon, 15 Jul 2013 13:24:23 -0400 | From | Dave Jones <> | Subject | Re: nohz: Warn if the machine can not perform nohz_full |
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On Mon, Jul 15, 2013 at 07:18:02PM +0200, Frederic Weisbecker wrote:
> > So I guess you guys never want this to be enabled on distro kernels ? > > If that's the case, can you add something to that effect in Kconfig ? > > I believe we want it to be enabled on distros in the long term. But right now it would > be a bad idea until the off case (nohz_full= parameter empty) is carefully optimized. > I'm currently working on that. > > Now for the unstable tsc, which is what it's about on the above code block, we need > the tick to be there to leverage the sched clock madness. May be there could be some > other solution that could work along full dynticks but for now we chose the easy path. > > Are broken TSCs that common?
I just hit one apparently. http://paste.fedoraproject.org/25421/73907845/raw/ That's a fairly recent Atom board, so I suspect it's not uncommon on that platform.
> Also what is the preffered way to tell the distros that they shouldn't enable that option > for now? Here is what we currently have in the tail of the related Kconfig help: > > This is implemented at the expense of some overhead in user <-> kernel > transitions: syscalls, exceptions and interrupts. Even when it's > dynamically off.
"This feature is not ready to be deployed" ?
"This will taint the kernel if it decides it can't work" ?
Dave
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