Re: [PATCH tip/core/rcu] Make RCU_FAST_NO_HZ respect nohz= bootparameter

[Josh Triplett]

On Thu, Jul 05, 2012 at 03:37:31PM -0700, Paul E. McKenney wrote:
> If the nohz= boot parameter disables nohz, then RCU_FAST_NO_HZ needs to
> also disable itself.  This commit therefore checks for tick_nohz_enabled
> being zero, disabling rcu_prepare_for_idle() if so.  This patch assumes
> that tick_nohz_enabled can change at runtime: If this is not the case,
> then a simpler approach suffices.

Allowing nohz to change at runtime seems like an entirely unnecessary
bit of added complexity.  (So does having a boot parameter for it, but
that one at least seems easier to handle.)

What would the patch look like if you can assume nohz will never change
at runtime?  And does anyone have a use case for changing nohz at
runtime, rather than at boot time?

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