Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1185153 > unrolled thread

Re: CONFIG_NO_HZ_FULL restricts cpu usage to the equivalent of one in 4.2

Back to article view | Back to linux.kernel

This discussion starts older than the indexed window; earlier articles aren't shown. The article labeled Started by below is the oldest one visible, not the original post.

Contents

  Re: CONFIG_NO_HZ_FULL restricts cpu usage to the equivalent of one  in 4.2 Ken Moffat <zarniwhoop@ntlworld.com> - 2015-07-16 02:40 +0200

#1185153 — Re: CONFIG_NO_HZ_FULL restricts cpu usage to the equivalent of one in 4.2

On Wed, Jul 15, 2015 at 09:11:46PM +0200, Frederic Weisbecker wrote:
> 2015-07-15 18:27 GMT+02:00 Ken Moffat <zarniwhoop@ntlworld.com>:
> >
> > The config differences follow.  Perhaps it is actually one of the
> > subsequent choices that is the problem.  And I guess it could still
> > be a gcc-5.1 issue.
> >
> > --- config-4.2-initial  2015-07-15 16:25:12.548005751 +0100
> > +++ config-4.2-speed-ok 2015-07-15 17:00:50.919998703 +0100
> > @@ -104,11 +104,8 @@
> >  CONFIG_TICK_ONESHOT=y
> >  CONFIG_NO_HZ_COMMON=y
> >  # CONFIG_HZ_PERIODIC is not set
> > -# CONFIG_NO_HZ_IDLE is not set
> > -CONFIG_NO_HZ_FULL=y
> > -CONFIG_NO_HZ_FULL_ALL=y
> 
> You had CONFIG_NO_HZ_FULL_ALL enabled? Because that would indeed
> produce that effect since it isolates all CPUs but 0 off sched
> domains.
> 
> Which means that basically only CPU 0 runs user tasks unless you
> forces these otherwise.

Thanks.  I'll put it down to a bad .config choice, although it was
fine on early 4.1.  While I was starting to bisect, I noticed that
on the A10 everything was happening on CPU 0 - not sure if that was
happening on the original box, but for the moment it sounds likely.

ĸen
-- 
This one goes up to eleven!
--
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/

[toc] | [standalone]

Back to top | Article view | linux.kernel

csiph-web