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? -- Regards Gui Jianfeng -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel