[dm-devel] Re: [PATCH] io-controller: optimization for iog deletion when elevator exiting

[Vivek Goyal <vgoyal redhat com>]

On Tue, Jun 30, 2009 at 10:14:48AM -0700, Nauman Rafique wrote:
> On Mon, Jun 29, 2009 at 7:06 AM, Vivek Goyal<vgoyal redhat com> wrote:
> > On Mon, Jun 29, 2009 at 01:27:47PM +0800, Gui Jianfeng wrote:
> >> Hi Vivek,
> >>
> >> There's no need to travel the iocg->group_data for each iog
> >> when exiting a elevator, that costs too much. An alternative
> >> solution is reseting iocg_id as soon as an io group unlinking
> >> from a iocg. Make a decision that whether it's need to carry
> >> out deleting action by checking iocg_id.
> >>
> >
> > Thanks Gui. This makes sense to me. We can check iog->iocg_id to determine
> > wheter group is still on iocg list or not instead of traversing the list.
> >
> > Nauman, do you see any issues with the patch?
> 
> Looks like this should work. The only iog with zero id is associated
> with root group, which gets deleted outside of this function anyways.
> 

Minor correction. Even root group has id "1" and not zero. 0 is associated
with error when cgroup is not present.

Thanks
Vivek