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    Subject[RFC, PATCH 6/9] CPU Controller V2 - Handle dont care groups
    Deal with task-groups whose bandwidth hasnt been explicitly set by the
    administrator. Unallocated CPU bandwidth is equally distributed among such
    "don't care" groups.

    Signed-off-by : Srivatsa Vaddagiri <vatsa@in.ibm.com>

    ---

    linux-2.6.18-root/include/linux/sched.h | 2
    linux-2.6.18-root/kernel/sched.c | 92 ++++++++++++++++++++++++++++++--
    2 files changed, 88 insertions(+), 6 deletions(-)

    diff -puN kernel/sched.c~cpu_ctlr_handle_dont_cares kernel/sched.c
    --- linux-2.6.18/kernel/sched.c~cpu_ctlr_handle_dont_cares 2006-09-28 16:40:28.772666712 +0530
    +++ linux-2.6.18-root/kernel/sched.c 2006-09-28 17:23:16.989238448 +0530
    @@ -226,6 +226,12 @@ static DEFINE_PER_CPU(struct task_grp_rq
    /* task-group object - maintains information about each task-group */
    struct task_grp {
    unsigned short ticks, long_ticks; /* bandwidth given to task-group */
    + int left_over_pct;
    + int total_dont_care_grps;
    + int dont_care; /* Does this group care for its bandwidth ? */
    + struct task_grp *parent;
    + struct list_head dont_care_list;
    + struct list_head list;
    struct task_grp_rq *rq[NR_CPUS]; /* runqueue pointer for every cpu */
    };

    @@ -7031,6 +7037,12 @@ void __init sched_init(void)

    init_task_grp.ticks = CPU_CONTROL_SHORT_WINDOW; /* 100% bandwidth */
    init_task_grp.long_ticks = NUM_LONG_TICKS;
    + init_task_grp.left_over_pct = 100; /* 100% unallocated bandwidth */
    + init_task_grp.parent = NULL;
    + init_task_grp.total_dont_care_grps = 1; /* init_task_grp itself */
    + init_task_grp.dont_care = 1;
    + INIT_LIST_HEAD(&init_task_grp.dont_care_list);
    + list_add_tail(&init_task_grp.list, &init_task_grp.dont_care_list);

    for_each_possible_cpu(i) {
    struct rq *rq;
    @@ -7195,8 +7207,31 @@ void set_curr_task(int cpu, struct task_

    #ifdef CONFIG_CPUMETER

    +/* Distribute left over bandwidth equally to all "dont care" task groups */
    +static void recalc_dontcare(struct task_grp *tg_root)
    +{
    + int ticks;
    + struct list_head *entry;
    +
    + if (!tg_root->total_dont_care_grps)
    + return;
    +
    + ticks = ((tg_root->left_over_pct / tg_root->total_dont_care_grps) *
    + CPU_CONTROL_SHORT_WINDOW) / 100;
    +
    + list_for_each(entry, &tg_root->dont_care_list) {
    + struct task_grp *tg;
    + int i;
    +
    + tg = list_entry(entry, struct task_grp, list);
    + tg->ticks = ticks;
    + for_each_possible_cpu(i)
    + tg->rq[i]->ticks = tg->ticks;
    + }
    +}
    +
    /* Allocate runqueue structures for the new task-group */
    -void *sched_alloc_group(void)
    +void *sched_alloc_group(struct task_grp *tg_parent)
    {
    struct task_grp *tg;
    struct task_grp_rq *tgrq;
    @@ -7208,6 +7243,10 @@ void *sched_alloc_group(void)

    tg->ticks = CPU_CONTROL_SHORT_WINDOW;
    tg->long_ticks = NUM_LONG_TICKS;
    + tg->parent = tg_parent;
    + tg->dont_care = 1;
    + tg->left_over_pct = 100;
    + INIT_LIST_HEAD(&tg->dont_care_list);

    for_each_possible_cpu(i) {
    tgrq = kzalloc(sizeof(*tgrq), GFP_KERNEL);
    @@ -7217,6 +7256,15 @@ void *sched_alloc_group(void)
    task_grp_rq_init(tgrq, tg);
    }

    + if (tg->parent) {
    + tg->parent->total_dont_care_grps++;
    + list_add_tail(&tg->list, &tg->parent->dont_care_list);
    + recalc_dontcare(tg->parent);
    + } else {
    + tg->total_dont_care_grps = 1;
    + list_add_tail(&tg->list, &tg->dont_care_list);
    + }
    +
    return tg;
    oom:
    while (i--)
    @@ -7230,6 +7278,16 @@ oom:
    void sched_dealloc_group(struct task_grp *tg)
    {
    int i;
    + struct task_grp *tg_root = tg->parent;
    +
    + if (!tg_root)
    + tg_root = tg;
    +
    + if (tg->dont_care) {
    + tg_root->total_dont_care_grps--;
    + list_del(&tg->list);
    + recalc_dontcare(tg_root);
    + }

    for_each_possible_cpu(i)
    kfree(tg->rq[i]);
    @@ -7240,12 +7298,33 @@ void sched_dealloc_group(struct task_grp
    /* Assign quota to this group */
    int sched_assign_quota(struct task_grp *tg, int quota)
    {
    - int i;
    + int i, old_quota = 0;
    + struct task_grp *tg_root = tg->parent;
    +
    + if (!tg_root)
    + tg_root = tg;
    +
    + if (!tg->dont_care)
    + old_quota = (tg->ticks * 100) / CPU_CONTROL_SHORT_WINDOW;
    +
    + if (quota > (tg_root->left_over_pct - old_quota))
    + return -EINVAL;
    +
    + if (tg->dont_care) {
    + tg->dont_care = 0;
    + tg_root->total_dont_care_grps--;
    + list_del(&tg->list);
    + }

    tg->ticks = (quota * CPU_CONTROL_SHORT_WINDOW) / 100;
    + for_each_possible_cpu(i) {
    + tg->rq[i]->ticks = tg->ticks;
    + tg->rq[i]->long_ticks = tg->long_ticks;
    + }

    - for_each_possible_cpu(i)
    - tg->rq[i]->ticks = tg->ticks;
    + /* xxx: needs some locking */
    + tg_root->left_over_pct -= (quota - old_quota);
    + recalc_dontcare(tg_root);

    return 0;
    }
    @@ -7258,7 +7337,10 @@ static inline int cpu_quota(struct task_
    /* Return assigned quota for this group */
    int sched_get_quota(struct task_grp *tg)
    {
    - return cpu_quota(tg);
    + if (tg->dont_care)
    + return 0;
    + else
    + return cpu_quota(tg);
    }

    /*
    diff -puN include/linux/sched.h~cpu_ctlr_handle_dont_cares include/linux/sched.h
    --- linux-2.6.18/include/linux/sched.h~cpu_ctlr_handle_dont_cares 2006-09-28 16:40:28.777665952 +0530
    +++ linux-2.6.18-root/include/linux/sched.h 2006-09-28 16:40:28.801662304 +0530
    @@ -1615,7 +1615,7 @@ static inline int try_to_freeze(void) {
    #ifdef CONFIG_CPUMETER
    struct task_grp;
    struct task_grp_ops {
    - void *(*alloc_group)(void);
    + void *(*alloc_group)(struct task_grp *grp_parent);
    void (*dealloc_group)(struct task_grp *grp);
    int (*assign_quota)(struct task_grp *grp, int quota);
    int (*pre_move_task)(struct task_struct *tsk, unsigned long *,
    _
    --
    Regards,
    vatsa
    -
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