Re: [PATCH] sched/rt: Fix rq->clock_update_flags < RQCF_ACT_SKIP warning

From: Matt Fleming <matt@codeblueprint.co.uk>
To: Davidlohr Bueso <dave@stgolabs.net>
Cc: peterz@infradead.org, mingo@kernel.org, efault@gmx.de,
	rostedt@goodmis.org, linux-kernel@vger.kernel.org,
	Davidlohr Bueso <dbueso@suse.de>
Subject: Re: [PATCH] sched/rt: Fix rq->clock_update_flags < RQCF_ACT_SKIP warning
Date: Tue, 3 Apr 2018 13:39:48 +0100	[thread overview]
Message-ID: <20180403123948.GA4771@codeblueprint.co.uk> (raw)
In-Reply-To: <20180402164954.16255-1-dave@stgolabs.net>

On Mon, 02 Apr, at 09:49:54AM, Davidlohr Bueso wrote:
> 
> We can get rid of it be the "traditional" means of adding an update_rq_clock() call
> after acquiring the rq->lock in do_sched_rt_period_timer().
> 
> The case for the rt task throttling (which this workload also hits) can be ignored in
> that the skip_update call is actually bogus and quite the contrary (the request bits
> are removed/reverted). By setting RQCF_UPDATED we really don't care if the skip is
> happening or not and will therefore make the assert_clock_updated() check happy.
> 
> Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
> ---
>  kernel/sched/rt.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
> index 86b77987435e..ad13e6242481 100644
> --- a/kernel/sched/rt.c
> +++ b/kernel/sched/rt.c
> @@ -839,6 +839,8 @@ static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun)
>  			continue;
>  
>  		raw_spin_lock(&rq->lock);
> +		update_rq_clock(rq);
> +
>  		if (rt_rq->rt_time) {
>  			u64 runtime;

Looks good to me.

Reviewed-by: Matt Fleming <matt@codeblueprint.co.uk>