On Mon 13-09-21 21:32:25, Shakeel Butt wrote: > On Mon, Sep 13, 2021 at 1:37 AM Michal Hocko <mhocko@xxxxxxxx> wrote: > > > [...] > > > However Shakeel Butt pointed that there are much more popular objects > > > with the same life time and similar memory consumption, the accounting > > > of which was decided to be rejected for performance reasons. > > > > Is there any measurable performance impact in this particular case? > > > > I don't think there was any regression report or any performance > evaluation. Linus raised the concern on the potential performance > impact. I suggested to backoff for this allocation for now and revisit > again once we have improved the memcg accounting for kernel memory. I am fine with the change, I am just not satisfied with the justification. It is not really clear what the intention is except that Linus wanted it. I have already asked Vasily to provide more explanation. E.g. this part really begs for clarification " This object can consume up to 2 pages, syscall is sleeping one, size and duration can be controlled by user, and this allocation can be repeated by many thread at the same time. " It sounds like a problem, except it is not because? A worst case scenario evaluation would be beneficial for example Thanks! -- Michal Hocko SUSE Labs
