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Thu, 17 Jul 2025 02:05:18 -0700 (PDT) X-Google-Smtp-Source: AGHT+IGKzBA+nIDslTzLBOt+Y6PtFpV+b9Z3/qQFQH4pOsV0FRQTn4v1SAc/e4McY4He/aMxKQlALw== X-Received: by 2002:a05:6000:4719:b0:3b5:dbd8:ad5f with SMTP id ffacd0b85a97d-3b60dd91d5amr4584054f8f.58.1752743118149; Thu, 17 Jul 2025 02:05:18 -0700 (PDT) Received: from jlelli-thinkpadt14gen4.remote.csb ([151.43.229.86]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3b5e8bd1647sm20068276f8f.1.2025.07.17.02.05.16 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 17 Jul 2025 02:05:17 -0700 (PDT) Date: Thu, 17 Jul 2025 11:05:14 +0200 From: Juri Lelli To: markus.stockhausen@gmx.de Cc: peterz@infradead.org, 'Chris Packham' , bjorn@mork.no, mingo@redhat.com, vincent.guittot@linaro.org, anna-maria@linutronix.de, frederic@kernel.org, tglx@linutronix.de, linux-kernel@vger.kernel.org Subject: Re: task_non_contending() for fair_server leads to timer retries Message-ID: References: <085d01dbf596$44286880$cc793980$@gmx.de> 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=us-ascii Content-Disposition: inline In-Reply-To: <085d01dbf596$44286880$cc793980$@gmx.de> Hi, On 15/07/25 16:39, markus.stockhausen@gmx.de wrote: > Hi Peter, > > I'm currently investigating issues with the timer-rtl-otto driver in > 6.12 longterm on the Realtek MIPS switch platform (Chris is working > hard to upstream this). While doing so I observed that timer retries > continually increase (~6/second) according to /proc/timer_list. The > system is otherwise totally idle. 6.6 longterm does not show that issue. > I'm unsure if this is related but documentation reads like "that's bad". > > To be sure about this one I nailed it down to the fair server. Apologies for interjecting before Peter had a chance to reply, but I had a first look and I wonder if this recent patch from Peter (on tip/sched/core atm) can already help with the issue, as it should reduce the number of dl-server dequeues: cccb45d7c4295 ("sched/deadline: Less agressive dl_server handling") Can you please check what you see with it? Thanks! Juri