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Mon, 20 Apr 2026 09:02:07 +0000 Message-ID: Date: Mon, 20 Apr 2026 17:01:53 +0800 User-Agent: Mozilla Thunderbird Subject: Re: [Patch v4 00/22] Cache aware scheduling To: Qais Yousef , Tim Chen CC: Peter Zijlstra , Ingo Molnar , "K Prateek Nayak" , "Gautham R . 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I am not certain which strategy is preferable, as it largely depends on the use case and workload. We intend to evaluate push-based load balancing on top of the existing lb-based cache-aware placement logic. > I think in practice admins will care about specific applications to > be kept within a single LLC, and if they are willing to spend the effort, they > can tag specific tasks of a specific application. > It seems to me that there are multiple use cases. In one scenario, the administrator (including daemons) is responsible for tagging workloads. In another, users prefer the OS to handle automatic placement without any userspace involvement. > Also QoS IMHO should be viewed as a scarce resource. For best effort delivery > (which is the best we can do in reality, this is not hard real time system), it > is easier to provide good best effort when the average noise level is low, ie: > few tasks are required to be kept within the same LLC. If we overcommit often, > we will crumble often. So IMHO the key is to delegate to userspace to tag, and I suppose there are two scenarios. The first is enabling/disabling aggregation for a group of tasks, and the second is task tagging. For the first scenario, this can be applied either process-wide or cgroup-wide by providing a flag, without requiring users to explicitly tag individual tasks. The second scenario is an enhancement to support fine-grained control over a specific task. If schedqos only supports scenario2, the user has to tag every task to support scenario1. thanks, Chenyu