> On 4/1/08, Pavel Machek <pavel@ucw.cz> wrote:
>  > > > > --- a/include/linux/cgroup_subsys.h
>  > > > > +++ b/include/linux/cgroup_subsys.h
>  > > > > @@ -42,3 +42,9 @@ SUBSYS(mem_cgroup)
>  > > > > #endif
>  > > > >
>  > > > > /* */
>  > > > > +
>  > > > > +#ifdef CONFIG_CGROUP_DEVICE
>  > > > > +SUBSYS(devices)
>  > > > > +#endif
>  > > > > +
>  > > > > +/* */
>  > > >
>  > > > I don't know what this is, but it does not look like C...
>  > >
>  > > Huh?
>  >
>  > Empty comments as separators?
> 
>  They help when multiple people add such SUBSYS things and
>  do not have to fight rejects.
> 

Why not provide a interface to add subsystems at run-time instead?
Are there any reason for not letting a subsystem to be implemented as a
loadable module? IOW make cgroups usable by modules?

Thanks
Nikanth Karthikesan


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On Mon, 2008-04-07 at 22:43 -0700, Paul Menage wrote:
> On Mon, Apr 7, 2008 at 10:39 PM, Nikanth Karthikesan <knikanth@suse.de> wrote:
> >
> >  Why not provide a interface to add subsystems at run-time instead?
> >  Are there any reason for not letting a subsystem to be implemented as a
> >  loadable module? IOW make cgroups usable by modules?
> >
> 
> Having all the subsystems declared at compile time makes a lot of
> things (number of subsystems, size of css_set, etc) statically known,
> which makes the code clearer and more importantly eliminates a bunch
> of locking/synchronization overhead.
> 

true

> It would be possible to make cgroups support dynamically-loaded
> subsystems, and in fact, some of the earliest cgroups patches did
> support this, for a predefined max number of subsystems. But it would
> introduce more complexity and overhead.
> 
> I'd rather not add support for this without a strong case of a
> subsystem that really needs to be dynamically loaded.

There were some band-width control patches based on cfq + cgroups, which
I guess will mandate cfq to be built-in?

Thanks
Nikanth Karthikesan

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