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[87.17.196.109]) by smtp.gmail.com with ESMTPSA id y6sm535432wrt.80.2020.09.23.10.54.21 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 23 Sep 2020 10:54:22 -0700 (PDT) Subject: Re: [PATCH 7/9] sched: Add migrate_disable() To: peterz@infradead.org, Thomas Gleixner Cc: mingo@kernel.org, linux-kernel@vger.kernel.org, bigeasy@linutronix.de, qais.yousef@arm.com, swood@redhat.com, valentin.schneider@arm.com, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, vincent.donnefort@arm.com References: <20200921163557.234036895@infradead.org> <20200921163845.769861942@infradead.org> <87v9g7aqjd.fsf@nanos.tec.linutronix.de> <86929eee-36da-93a5-5280-00e6df1ef496@redhat.com> <87v9g4ao8h.fsf@nanos.tec.linutronix.de> <20200923170809.GY1362448@hirez.programming.kicks-ass.net> From: Daniel Bristot de Oliveira Message-ID: Date: Wed, 23 Sep 2020 19:54:20 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.11.0 MIME-Version: 1.0 In-Reply-To: <20200923170809.GY1362448@hirez.programming.kicks-ass.net> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 9/23/20 7:08 PM, peterz@infradead.org wrote: > On Wed, Sep 23, 2020 at 10:31:10AM +0200, Thomas Gleixner wrote: >> In practice migrate disable could be taken into account on placement >> decisions, but yes we don't have anything like that at the moment. > I think at the very least we should do some of that. > > The premise is wanting to run the M highest priority tasks, when a CPU > drops priority, it tries to PULL a higher priority task towards itself. > If this PULL selects a migrate_disable() tasks, it means the task is in > the M highest prio tasks. > > Since obviously that task cannot get pulled, we should then pull the > current running task of that CPU, this would then allow the > migrate_disable() task to resume execution. > > I'll go try and cook up something along those lines... > sounds promising... -- Daniel