Re: nohz: Warn if the machine can not perform nohz_full

From: Steven Rostedt
Date: Mon Jul 15 2013 - 15:30:32 EST


On Mon, 2013-07-15 at 14:56 -0400, Dave Jones wrote:
> On Mon, Jul 15, 2013 at 02:49:42PM -0400, Steven Rostedt wrote:
>
> Is a printk not enough for that purpose ? Tainting the kernel is kinda anti-social.
>

printk's don't usually get peoples attention. Taints and warnings do. If
the hardware doesn't allow for nohz-full, and the only way to enable it
is via kernel command line, how do you scream to the user that it isn't
going to work.

We could do a large banner saying:

***************************************************************
***************************************************************
***************************************************************
***************************************************************
*** UNSTABLE TSC ***
*** NO_HZ_FULL disabled ***
***************************************************************
***************************************************************
***************************************************************
***************************************************************


And not do the warning. Maybe that will get peoples attentions?

But then again, this could be lost in the boot up if the box prints a
lot of data.

-- Steve


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