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[79.51.196.100]) by smtp.gmail.com with ESMTPSA id w19-20020a1709061f1300b00a4e03823107sm6925730ejj.210.2024.04.10.05.24.14 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 10 Apr 2024 05:24:15 -0700 (PDT) Message-ID: <88144494-33f1-4f43-88c0-885ea6b87e07@redhat.com> Date: Wed, 10 Apr 2024 14:24:14 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH 0/2] Disable RT-throttling for idle-inject threads Content-Language: en-US, pt-BR, it-IT To: Peter Zijlstra , Atul Kumar Pant Cc: mingo@redhat.com, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com, rafael@kernel.org, daniel.lezcano@linaro.org, kernel@quicinc.com, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org References: <20240410045417.3048209-1-quic_atulpant@quicinc.com> <20240410085441.GA21455@noisy.programming.kicks-ass.net> <20240410112933.GA3190796@hu-atulpant-hyd.qualcomm.com> <20240410114609.GA40213@noisy.programming.kicks-ass.net> From: Daniel Bristot de Oliveira In-Reply-To: <20240410114609.GA40213@noisy.programming.kicks-ass.net> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 4/10/24 13:46, Peter Zijlstra wrote: > Also, we'll be replacing the throttling code with DL servers 'soonish' > at which point all this will stop working anyway, since DL will preempt > anything FIFO, including your idle injection crud. +1 also, given that the code spins with preempt disabled, with dl server it could even become a non-rt thread... FIFO RUNNING DL_SERVER activates their loop disables preemption() run() enable preemption() DL_SERVE throttled FIFO BACK So, there will be no need for this busy loop to be RT. Anyways, it breaks RT and DL if it keeps running for too long... It can also cause complaints like RCU stalls and loong wait on locks, e.g., on kworkers... -- Daniel