On Wed 13-01-21 19:20:17, Muchun Song wrote: > On Wed, Jan 13, 2021 at 7:15 PM Oscar Salvador <osalvador@xxxxxxx> wrote: > > > > On Wed, Jan 13, 2021 at 07:11:06PM +0800, Muchun Song wrote: > > > If there is no task to be scheduled. Here is just a while loop. > > > The cpu_relax is a good thing to insert into busy-wait loops, > > > right? > > > > But if the race window is that small, does it make sense? > > Actually, there is one exception. The race window could > become larger. If the page is freed via a workqueue (see > free_huge_page()). In this case, the cpu_relax() can > make sense. Right? The system would have to be under serious stress for WQ to clog. I do not expect there would be nothing runable at that stage. Possible? Maybe but if that matters than a short sleep would be more preferable than cpu_relax. -- Michal Hocko SUSE Labs
