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[2.102.14.151]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3b79c3c33fesm27226884f8f.29.2025.08.07.06.23.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 07 Aug 2025 06:23:35 -0700 (PDT) Date: Thu, 7 Aug 2025 14:23:33 +0100 From: Juri Lelli To: Kuyo Chang Cc: Ingo Molnar , Peter Zijlstra , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , Matthias Brugger , AngeloGioacchino Del Regno , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org Subject: Re: [PATCH] sched/deadline: Add DL server activated message Message-ID: References: <20250805155347.1693676-1-kuyo.chang@mediatek.com> <9f91f77e5f39857aa84373fe1ae504de2a881533.camel@mediatek.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <9f91f77e5f39857aa84373fe1ae504de2a881533.camel@mediatek.com> On 07/08/25 15:52, Kuyo Chang wrote: > On Thu, 2025-08-07 at 08:15 +0100, Juri Lelli wrote: > > > > External email : Please do not click links or open attachments until > > you have verified the sender or the content. > > > > > > Hi, > > > > On 05/08/25 23:53, Kuyo Chang wrote: > > > From: kuyo chang > > > > > > The DL server is introduced as a replacement for realtime > > > throttling. > > > When RT throttling is activated, a message > > > "sched: RT throttling activated" is shown. However, it is currently > > > difficult for users to know when the DL server is activated. > > > > > > This patch adds a similar message to indicate when the DL server > > > is activated, which helps users debug RT/CFS contention issues. > > > > > > Signed-off-by: kuyo chang > > > --- > > >  kernel/sched/deadline.c | 3 +++ > > >  1 file changed, 3 insertions(+) > > > > > > diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c > > > index e2d51f4306b3..8e0de6cdb980 100644 > > > --- a/kernel/sched/deadline.c > > > +++ b/kernel/sched/deadline.c > > > @@ -2042,6 +2042,9 @@ enqueue_dl_entity(struct sched_dl_entity > > > *dl_se, int flags) > > >       } > > > > > >       __enqueue_dl_entity(dl_se); > > > + > > > +     if (dl_server(dl_se)) > > > +             printk_deferred_once("sched: dl_server activated\n"); > > >  } > > > > Not sure if we want/need this, but, if we do, I believe > > fair_server_pick_task() might be a better place to put it, as it's > > really when the dl-server is called to do its job. > > > > Thanks for your suggestion, maybe the minor patch as below > > diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c > index e2d51f4306b3..82d1091e56f5 100644 > --- a/kernel/sched/deadline.c > +++ b/kernel/sched/deadline.c > @@ -2395,6 +2395,7 @@ static struct task_struct *__pick_task_dl(struct > rq *rq) > goto again; > } > rq->dl_server = dl_se; > + printk_deferred_once("sched: dl_server activated\n"); Guess it could work. If we are going to add this, maybe printing information about the task dl-server is servicing might also be interesting.