On Sat, 23 Jan 2021 at 19:31, Qais Yousef <qais.yousef@xxxxxxx> wrote: > > On 01/20/21 15:46, Vincent Guittot wrote: > > > +.TP > > > +For example: > > > +.B uclampset \-s > > > +.I -m\ 512 > > > +.I -M\ 700 > > > +.PP > > > +will prevent any task from being boosted higher than 512. And all tasks in the > > > > will prevent any task from being boosted higher than 700 > > 700 or 512 you mean here? > > > or > > will ensure any task to be boosted higher than 512 > > It is certainly not that. That's the confusion I was trying to clear up in this > note. The system values are _constraints_. It sets an upper bound on the > maximum uclamp_min/max value the system will apply. > > For example if a task::uclamp_min=1024 but the system::uclamp_min=512 512, then > effectively the task will only be boosted to 512. Once this restriction is left > by setting system::uclamp_min=1024 again, then the task will get the boost > value it requested. ok, I got confused because uclamp -p PID -min 512 - M 700 and uclamp -s -min 512 - M 700 look quite similar but their behaviors are quite different. I mean uclamp -p PID -min 512 - M 700 will ensure that the task's utilization will be always reported in the range [512:700] The behavior is the same for the cgroup with cpu.uclamp.min and cpu.uclamp.max whereas uclamp -s -min 512 - M 700 will do the opposite; i.e. the min of task's utilization range will never be above 512 TBH I don't know how to make it clear that the behavior of -min is the opposite between -p and -s > > I'm open to suggestions on how to better explain this.. > > Thanks > > -- > Qais Yousef
