On Tue, 10 Jan 2023 08:50:28 -0300 Marcelo Tosatti <mtosatti@xxxxxxxxxx> > On Tue, Jan 10, 2023 at 10:43:56AM +0800, Hillf Danton wrote: > > On 9 Jan 2023 11:12:49 -0300 Marcelo Tosatti <mtosatti@xxxxxxxxxx> > > > > > > Yes, but if you do not return to userspace, then the per-CPU vm > > > statistics can be dirty indefinitely. > > > > Could you specify the reasons for failing to return to userspace, > > given it is undesired intereference for the shepherd to queue work > > on the isolated CPUs. > > Any system call that takes longer than the threshold to sync vmstats. Which ones? If schedule() occurs during syscall because of acquiring mutex for instance then anything on the isolated runqueue, including workqueue worker shepherd wakes up, can burn CPU cycles without undesired intereference produced. > > Or a long running kernel thread, for example: It is a buggyyyy example. > > https://stackoverflow.com/questions/65111483/long-running-kthread-and-synchronize-net
