On Mon, Jul 06, 2009 at 10:46:19AM +0800, Gui Jianfeng wrote:
> Vivek Goyal wrote:
> ...
> > +static struct io_group *
> > +io_group_chain_alloc(struct request_queue *q, void *key, struct cgroup *cgroup)
> > +{
> > + struct io_cgroup *iocg;
> > + struct io_group *iog, *leaf = NULL, *prev = NULL;
> > + gfp_t flags = GFP_ATOMIC | __GFP_ZERO;
> > +
> > + for (; cgroup != NULL; cgroup = cgroup->parent) {
> > + iocg = cgroup_to_io_cgroup(cgroup);
> > +
> > + iog = io_cgroup_lookup_group(iocg, key);
> > + if (iog != NULL) {
> > + /*
> > + * All the cgroups in the path from there to the
> > + * root must have a io_group for efqd, so we don't
> > + * need any more allocations.
> > + */
> > + break;
> > + }
> > +
> > + iog = kzalloc_node(sizeof(*iog), flags, q->node);
> > + if (!iog)
> > + goto cleanup;
> > +
> > + iog->iocg_id = css_id(&iocg->css);
>
> Hi Vivek,
>
> IMHO, The io_cgroup id is nothing more than keeping track the corresponding iocg.
> So why not just store iocg pointer in io_group and just get rid of this complexity.
> I'd like to post a patch to do this change, what's your opinion?
>
Hi Gui,
You can try that but I suspect that there not much to be gained in
terms of number of lines of code or code complexity. Do try it out though
and we can then have a look at the patch.
Thanks
Vivek
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