Messages in this thread | | | Subject | Re: [RFC, PATCH 1/2] sched: allow the CFS group scheduler to have multiple levels | From | Peter Zijlstra <> | Date | Thu, 28 Feb 2008 20:42:46 +0100 |
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On Mon, 2008-02-25 at 19:47 +0530, Dhaval Giani wrote: > This patch makes the group scheduler multi hierarchy aware.
Ok, good thing to do in principle
> Signed-off-by: Dhaval Giani <dhaval@linux.vnet.ibm.com> > > --- > include/linux/sched.h | 2 +- > kernel/sched.c | 41 ++++++++++++++++++++++++----------------- > 2 files changed, 25 insertions(+), 18 deletions(-) > > Index: linux-2.6.25-rc2/include/linux/sched.h > =================================================================== > --- linux-2.6.25-rc2.orig/include/linux/sched.h > +++ linux-2.6.25-rc2/include/linux/sched.h > @@ -2031,7 +2031,7 @@ extern void normalize_rt_tasks(void); > > extern struct task_group init_task_group; > > -extern struct task_group *sched_create_group(void); > +extern struct task_group *sched_create_group(struct task_group *parent); > extern void sched_destroy_group(struct task_group *tg); > extern void sched_move_task(struct task_struct *tsk); > #ifdef CONFIG_FAIR_GROUP_SCHED > Index: linux-2.6.25-rc2/kernel/sched.c > =================================================================== > --- linux-2.6.25-rc2.orig/kernel/sched.c > +++ linux-2.6.25-rc2/kernel/sched.c > @@ -7155,10 +7155,11 @@ static void init_rt_rq(struct rt_rq *rt_ > } > > #ifdef CONFIG_FAIR_GROUP_SCHED > -static void init_tg_cfs_entry(struct rq *rq, struct task_group *tg, > - struct cfs_rq *cfs_rq, struct sched_entity *se, > - int cpu, int add) > +static void init_tg_cfs_entry(struct task_group *tg, struct cfs_rq *cfs_rq, > + struct sched_entity *se, int cpu, int add, > + struct sched_entity *parent) > { > + struct rq *rq = cpu_rq(cpu); > tg->cfs_rq[cpu] = cfs_rq; > init_cfs_rq(cfs_rq, rq); > cfs_rq->tg = tg; > @@ -7170,7 +7171,11 @@ static void init_tg_cfs_entry(struct rq > if (!se) > return; > > - se->cfs_rq = &rq->cfs; > + if (parent == NULL)
!parent ?
> + se->cfs_rq = &rq->cfs; > + else > + se->cfs_rq = parent->my_q; > + > se->my_q = cfs_rq; > se->load.weight = tg->shares; > se->load.inv_weight = div64_64(1ULL<<32, se->load.weight); > @@ -7244,7 +7249,8 @@ void __init sched_init(void) > * We achieve this by letting init_task_group's tasks sit > * directly in rq->cfs (i.e init_task_group->se[] = NULL). > */ > - init_tg_cfs_entry(rq, &init_task_group, &rq->cfs, NULL, i, 1); > + init_tg_cfs_entry(&init_task_group, &rq->cfs, > + NULL, i, 1, NULL); > init_tg_rt_entry(rq, &init_task_group, &rq->rt, NULL, i, 1); > #elif defined CONFIG_USER_SCHED > /* > @@ -7260,7 +7266,7 @@ void __init sched_init(void) > */ > init_tg_cfs_entry(rq, &init_task_group, > &per_cpu(init_cfs_rq, i), > - &per_cpu(init_sched_entity, i), i, 1); > + &per_cpu(init_sched_entity, i), i, 1, NULL); > > #endif > #endif /* CONFIG_FAIR_GROUP_SCHED */ > @@ -7630,7 +7636,8 @@ static void free_fair_sched_group(struct > kfree(tg->se); > } > > -static int alloc_fair_sched_group(struct task_group *tg) > +static int alloc_fair_sched_group(struct task_group *tg, > + struct task_group *parent) > { > struct cfs_rq *cfs_rq; > struct sched_entity *se; > @@ -7658,8 +7665,11 @@ static int alloc_fair_sched_group(struct > GFP_KERNEL|__GFP_ZERO, cpu_to_node(i)); > if (!se) > goto err; > - > - init_tg_cfs_entry(rq, tg, cfs_rq, se, i, 0); > + if (!parent) { > + init_tg_cfs_entry(tg, cfs_rq, se, i, 0, parent->se[i]); > + } else { > + init_tg_cfs_entry(tg, cfs_rq, se, i, 0, NULL); > + }
Looks like you got the cases switched, this looks like an instant NULL deref.
> } > > return 1; > @@ -7788,7 +7798,7 @@ static void free_sched_group(struct task > } > > /* allocate runqueue etc for a new task group */ > -struct task_group *sched_create_group(void) > +struct task_group *sched_create_group(struct task_group *parent) > { > struct task_group *tg; > unsigned long flags; > @@ -7798,7 +7808,7 @@ struct task_group *sched_create_group(vo > if (!tg) > return ERR_PTR(-ENOMEM); > > - if (!alloc_fair_sched_group(tg)) > + if (!alloc_fair_sched_group(tg, parent)) > goto err; > > if (!alloc_rt_sched_group(tg)) > @@ -8049,7 +8059,7 @@ static inline struct task_group *cgroup_ > static struct cgroup_subsys_state * > cpu_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cgrp) > { > - struct task_group *tg; > + struct task_group *tg, *parent; > > if (!cgrp->parent) { > /* This is early initialization for the top cgroup */ > @@ -8057,11 +8067,8 @@ cpu_cgroup_create(struct cgroup_subsys * > return &init_task_group.css; > } > > - /* we support only 1-level deep hierarchical scheduler atm */ > - if (cgrp->parent->parent) > - return ERR_PTR(-EINVAL); > - > - tg = sched_create_group(); > + parent = cgroup_tg(cgrp->parent); > + tg = sched_create_group(parent); > if (IS_ERR(tg)) > return ERR_PTR(-ENOMEM); >
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