[dm-devel] Re: IO scheduler based IO controller V10

[Ryo Tsuruta <ryov valinux co jp>]

Hi,

Balbir Singh <balbir linux vnet ibm com> wrote:
> > > I think I must support dirty-ratio in memcg layer. But not yet.
> > 
> 
> We need to add this to the TODO list.
> 
> > OR...I'll add a bufferred-write-cgroup to track bufferred writebacks.
> > And add a control knob as
> >   bufferred_write.nr_dirty_thresh
> > to limit the number of dirty pages generetad via a cgroup.
> > 
> > Because memcg just records a owner of pages but not records who makes them
> > dirty, this may be better. Maybe I can reuse page_cgroup and Ryo's blockio
> > cgroup code.
> 
> Very good point, this is crucial for shared pages.
> 
> > 
> > But I'm not sure how I should treat I/Os generated out by kswapd.
> >
> 
> Account them to process 0 :)

How about accounting them to processes who make pages dirty? I think
that a process which consumes more memory should get penalty. However,
this allows a page request process to use other's bandwidth, but If
a user doesn't want to swap-out the memory, the user should allocate
enough memory for the process by using memcg in advance.

Thanks,
Ryo Tsuruta