Re: [PATCH tip/core/rcu 24/24] rcu: Conditionally compile RCU's eqs warnings

From	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH tip/core/rcu 24/24] rcu: Conditionally compile RCU's eqs warnings
Date	2015-06-29 23:00 +0200
Message-ID	<pGOjM-5WS-15@gated-at.bofh.it> (permalink)
References	<ppr0d-5FE-3@gated-at.bofh.it> <ppr0d-5FE-5@gated-at.bofh.it> <ppr0e-5FE-27@gated-at.bofh.it> <pGDHI-7uP-7@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Show all headers | View raw

On Mon, Jun 29, 2015 at 11:39:13AM +0200, Geert Uytterhoeven wrote:
> Hi Paul,
> 
> On Wed, May 13, 2015 at 12:30 AM, Paul E. McKenney
> <paulmck@linux.vnet.ibm.com> wrote:
> > --- a/lib/Kconfig.debug
> > +++ b/lib/Kconfig.debug
> > @@ -1373,6 +1373,17 @@ config RCU_TRACE
> >           Say Y here if you want to enable RCU tracing
> >           Say N if you are unsure.
> >
> > +config RCU_EQS_DEBUG
> > +       bool "Use this when adding any sort of NO_HZ support to your arch"
> 
> This sounds a bit fuzzy. Can you please provide a better one-line description?
> Thanks!

So the point of this Kconfig option is to provide WARN_ON()s that catch
bug such as telling RCU that a given CPU entered idle, but failing to
tell RCU when that CPU later leaves idle.  So how about this?

+       bool "Provide debugging asserts for adding NO_HZ support to an arch"

							Thanx, Paul

> > +       depends on DEBUG_KERNEL
> > +       help
> > +         This option provides consistency checks in RCU's handling of
> > +         NO_HZ.  These checks have proven quite helpful in detecting
> > +         bugs in arch-specific NO_HZ code.
> > +
> > +         Say N here if you need ultimate kernel/user switch latencies
> > +         Say Y if you are unsure
> 
> Gr{oetje,eeting}s,
> 
>                         Geert
> 
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
> 
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
>                                 -- Linus Torvalds
> 

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Back to linux.kernel | Previous | Next | Find similar | Unroll thread

Thread

Re: [PATCH tip/core/rcu 24/24] rcu: Conditionally compile RCU's eqs  warnings "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-06-29 23:00 +0200

csiph-web