Le Thu, Oct 29, 2026 at 02:41:28PM +0800, Peng Wang a écrit : > Hi Frederic, > > > Do you mean that your database runs better when hosts CPUs are in nohz_full? > > Yes. In our database tests, suppressing the host's non-idle > periodic tick improved performance, with the rest of the host > configuration unchanged.
Out of curiosity, for such database tests, only the host tick is off, not the guest tick, right? > > But how does this new interface help? Ie: why is it worse to have all CPUs > > in > > The tick policy itself can therefore affect guest performance. > A large host runs VMs for many customers with different workloads. > Customers create and release VMs independently, so the same host > CPU can be reassigned to a different workload while other VMs > remain running. > > We want to choose whether to retain the non-idle tick or allow its > suppression for the workload currently assigned to each CPU, and > revisit that choice when the CPU is reassigned. Per-CPU control > lets us do this without rebooting or taking CPUs offline. Ok in that case, do you know about the current work in progress to make nohz_full opt-able through cpusets? It implies taking the target CPUs offline shortly but the policy is to be setup before VM is launched, right? Thanks. -- Frederic Weisbecker SUSE Labs
