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It also > has to do the CID space consolidation work from a task work in the exit to > user space path. As that work is assigned to a random task related to a MM > this can inflict unwanted exit latencies. > > Implement the context switch parts of a strict ownership mechanism to > address this. > > This removes most of the work from the task which schedules out. Only > during transitioning from per CPU to per task ownership it is required to > drop the CID when leaving the CPU to prevent CID space exhaustion. Other > than that scheduling out is just a single check and branch. Same comment as for prior patch. [...] > struct mm_mm_cid { > + /* Hotpath read mostly members */ > struct mm_cid_pcpu __percpu *pcpu; > + unsigned int percpu; > + unsigned int transit; [...] > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -10495,6 +10495,7 @@ void mm_init_cid(struct mm_struct *mm, s > per_cpu_ptr(pcpu, cpu)->cid = MM_CID_UNSET; > > mm->mm_cid.max_cids = 0; > + mm->mm_cid.percpu = 0; I'm unsure where it appears (maybe later in the series ?), but I would have expected: mm->mm_cid.transit = 0; here. Other than those comments: Reviewed-by: Mathieu Desnoyers -- Mathieu Desnoyers EfficiOS Inc. https://www.efficios.com