Re: [PATCH v4 2/4] sched/isolation: Extend nohz_full to isolate managed IRQs

[Peter Zijlstra]

On Mon, Sep 28, 2020 at 02:35:27PM -0400, Nitesh Narayan Lal wrote:
> Extend nohz_full feature set to include isolation from managed IRQS. This

So you say it's for managed-irqs, the feature is actually called
MANAGED_IRQ, but, AFAICT, it does *NOT* in fact affect managed IRQs.

Also, as per Thomas' earlier points, managed-irqs are in fact perfectly
fine and don't need help at at...

> is required specifically for setups that only uses nohz_full and still
> requires isolation for maintaining lower latency for the listed CPUs.
> 
> Suggested-by: Frederic Weisbecker <frederic@xxxxxxxxxx>
> Signed-off-by: Nitesh Narayan Lal <nitesh@xxxxxxxxxx>
> ---
>  kernel/sched/isolation.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c
> index 5a6ea03f9882..9df9598a9e39 100644
> --- a/kernel/sched/isolation.c
> +++ b/kernel/sched/isolation.c
> @@ -141,7 +141,7 @@ static int __init housekeeping_nohz_full_setup(char *str)
>  	unsigned int flags;
>  
>  	flags = HK_FLAG_TICK | HK_FLAG_WQ | HK_FLAG_TIMER | HK_FLAG_RCU |
> -		HK_FLAG_MISC | HK_FLAG_KTHREAD;
> +		HK_FLAG_MISC | HK_FLAG_KTHREAD | HK_FLAG_MANAGED_IRQ;
>  
>  	return housekeeping_setup(str, flags);
>  }
> -- 
> 2.18.2
>