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([2601:188:ca00:a00:f844:fad5:7984:7bd7]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-4635ab5d891sm25609501cf.77.2024.11.15.16.40.14 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 15 Nov 2024 16:40:14 -0800 (PST) From: Waiman Long X-Google-Original-From: Waiman Long Message-ID: <5b8d92f6-0d55-4b43-844c-696e71266978@redhat.com> Date: Fri, 15 Nov 2024 19:40:13 -0500 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: [PATCH v2 1/2] sched/isolation: Exclude dynamically isolated CPUs from housekeeping masks To: =?UTF-8?Q?Michal_Koutn=C3=BD?= Cc: Tejun Heo , Johannes Weiner , Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , Frederic Weisbecker , linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, Costa Shulyupin , Daniel Wagner References: Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 11/15/24 10:45 AM, Michal Koutný wrote: > (Also someone mentioned that this could share lots of code with CPU > offlining/onlining.) Yes, that is true. The simplest way to do that is to offline the CPUs to be isolated, change the housekeeping masks and then online those CPUs again. That is good for managing a single isolated partition. However, Daniel had told me that CPU hotplug code could cause latency spike in existing isolated CPUs. That could be a problem if we have more than one isolated partitions to manage. So more investigation will be needed in this. This is still the direction we are going initially, but first we need to enable dynamic changes to the housekeeping masks first. Cheers, Longman