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As a result, both servers permanently contribute to global > > > bandwidth accounting, regardless of whether a BPF scheduler is active. > > > > > > While unused bandwidth can still be reclaimed at runtime by other classes, this > > > static reservation prevents RT from fully utilizing available headroom in > > > situations where one of the sched_ext or fair class is guaranteed to be inactive > > > (for example, when no BPF scheduler is loaded, or when sched_ext runs in full > > > mode and replaces fair). > > > > > > As discussed at the VIII OSPM summit in Cambridge [1], a better solution would > > > be to dynamically register and unregister deadline server bandwidth based on the > > > active sched_ext state. This allows the kernel to automatically enable bandwidth > > > accounting only for the scheduling class that is currently active, while > > > disabling it for inactive ones. > > > > > > This patch series implements this automatic register/unregister logic. Moreover, > > > the sched_ext total_bw kselftest is also modified to validate the correct > > > behavior across the different scheduling configurations and ensure that > > > bandwidth accounting follows the expected state transitions. > > > > > > [1] https://retis.santannapisa.it/ospm-summit/ > > > > > > Git tree: git://git.kernel.org/pub/scm/linux/kernel/git/arighi/linux.git dl-server-bw-v3 > > > > > > Changes in v3: > > > - Don't bypass __dl_overflow() for detached servers in dl_server_apply_params() > > > to reject oversized configs up front (reported by Sashiko) > > > - A potential divide-by-zero in dl_server_apply_params() reported by Sashiko > > > has been fixed in a separate patch (not introduced by this patch set): > > > https://lore.kernel.org/all/20260526100502.575774-1-arighi@nvidia.com/ > > > - Link to v2: https://lore.kernel.org/all/20260526082954.550958-1-arighi@nvidia.com/ > > > > This looks now good to me. > > > > Acked-by: Juri Lelli > > Thanks!, I've stuck them in queue:sched/core for the robots to chew on. > There was an absolutely trivial reject in ext.c that I fixed up, so > something moved around there. FYI, I re-ran all my tests with queue:sched/core, everything looks good on my side. Thanks, -Andrea