Re: [tip:sched/core] sched: Add 'autogroup' scheduling feature:automated per session task groups

From: Bharata B Rao
Date: Mon Dec 20 2010 - 08:08:26 EST

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On Tue, Nov 30, 2010 at 9:09 PM, tip-bot for Mike Galbraith
<efault@xxxxxx> wrote:
> Commit-ID: 5091faa449ee0b7d73bc296a93bca9540fc51d0a
> Gitweb: http://git.kernel.org/tip/5091faa449ee0b7d73bc296a93bca9540fc51d0a
> Author: Mike Galbraith <efault@xxxxxx>
> AuthorDate: Tue, 30 Nov 2010 14:18:03 +0100
> Committer: Ingo Molnar <mingo@xxxxxxx>
> CommitDate: Tue, 30 Nov 2010 16:03:35 +0100
>
> sched: Add 'autogroup' scheduling feature: automated per session task groups
>
> diff --git a/kernel/sched_debug.c b/kernel/sched_debug.c
> index e95b774..1dfae3d 100644
> --- a/kernel/sched_debug.c
> +++ b/kernel/sched_debug.c
> @@ -54,8 +54,7 @@ static unsigned long nsec_low(unsigned long long nsec)
> #define SPLIT_NS(x) nsec_high(x), nsec_low(x)
>
> #ifdef CONFIG_FAIR_GROUP_SCHED
> -static void print_cfs_group_stats(struct seq_file *m, int cpu,
> - struct task_group *tg)
> +static void print_cfs_group_stats(struct seq_file *m, int cpu, struct task_group *tg)
> {
> struct sched_entity *se = tg->se[cpu];
> if (!se)
> @@ -110,16 +109,6 @@ print_task(struct seq_file *m, struct rq *rq, struct task_struct *p)
> 0LL, 0LL, 0LL, 0L, 0LL, 0L, 0LL, 0L);
> #endif
>
> -#ifdef CONFIG_CGROUP_SCHED
> - {
> - char path[64];
> -
> - rcu_read_lock();
> - cgroup_path(task_group(p)->css.cgroup, path, sizeof(path));
> - rcu_read_unlock();
> - SEQ_printf(m, " %s", path);
> - }
> -#endif
> SEQ_printf(m, "\n");
> }
>
> @@ -147,19 +136,6 @@ static void print_rq(struct seq_file *m, struct rq *rq, int rq_cpu)
> read_unlock_irqrestore(&tasklist_lock, flags);
> }
>
> -#if defined(CONFIG_CGROUP_SCHED) && \
> - (defined(CONFIG_FAIR_GROUP_SCHED) || defined(CONFIG_RT_GROUP_SCHED))
> -static void task_group_path(struct task_group *tg, char *buf, int buflen)
> -{
> - /* may be NULL if the underlying cgroup isn't fully-created yet */
> - if (!tg->css.cgroup) {
> - buf[0] = '\0';
> - return;
> - }
> - cgroup_path(tg->css.cgroup, buf, buflen);
> -}
> -#endif
> -
> void print_cfs_rq(struct seq_file *m, int cpu, struct cfs_rq *cfs_rq)
> {
> s64 MIN_vruntime = -1, min_vruntime, max_vruntime = -1,
> @@ -168,16 +144,7 @@ void print_cfs_rq(struct seq_file *m, int cpu, struct cfs_rq *cfs_rq)
> struct sched_entity *last;
> unsigned long flags;
>
> -#if defined(CONFIG_CGROUP_SCHED) && defined(CONFIG_FAIR_GROUP_SCHED)
> - char path[128];
> - struct task_group *tg = cfs_rq->tg;
> -
> - task_group_path(tg, path, sizeof(path));
> -
> - SEQ_printf(m, "\ncfs_rq[%d]:%s\n", cpu, path);
> -#else
> SEQ_printf(m, "\ncfs_rq[%d]:\n", cpu);
> -#endif
> SEQ_printf(m, " .%-30s: %Ld.%06ld\n", "exec_clock",
> SPLIT_NS(cfs_rq->exec_clock));
>
> @@ -215,7 +182,7 @@ void print_cfs_rq(struct seq_file *m, int cpu, struct cfs_rq *cfs_rq)
> SEQ_printf(m, " .%-30s: %ld\n", "load_contrib",
> cfs_rq->load_contribution);
> SEQ_printf(m, " .%-30s: %d\n", "load_tg",
> - atomic_read(&tg->load_weight));
> + atomic_read(&cfs_rq->tg->load_weight));
> #endif
>
> print_cfs_group_stats(m, cpu, cfs_rq->tg);
> @@ -224,17 +191,7 @@ void print_cfs_rq(struct seq_file *m, int cpu, struct cfs_rq *cfs_rq)
>
> void print_rt_rq(struct seq_file *m, int cpu, struct rt_rq *rt_rq)
> {
> -#if defined(CONFIG_CGROUP_SCHED) && defined(CONFIG_RT_GROUP_SCHED)
> - char path[128];
> - struct task_group *tg = rt_rq->tg;
> -
> - task_group_path(tg, path, sizeof(path));
> -
> - SEQ_printf(m, "\nrt_rq[%d]:%s\n", cpu, path);
> -#else
> SEQ_printf(m, "\nrt_rq[%d]:\n", cpu);
> -#endif
> -

The above change as well as the recent changes due to tg_shares_up
improvements have two (undesirable ?) side effects on
/proc/sched_debug output.

The autogroup patchset removes the display of cgroup name from
sched_debug output.

On a 16 CPU system, with 2 groups having one task each and one task in
root group, the difference in o/p appears like this:

$ grep while1 sched_debug-2.6.37-rc5
R while1 2208 13610.855787 1960 120
13610.855787 19272.857661 0.000000 /2
R while1 2207 20255.605110 3160 120
20255.605110 31572.634065 0.000000 /1
R while1 2209 63913.721827 1273 120
63913.721827 12604.411880 0.000000 /

$ grep while1 sched_debug-2.6.37-rc5-tip
R while1 2173 17603.479529 2754 120
17603.479529 25818.279858 4.560010
R while1 2174 11435.667691 1669 120
11435.667691 16456.476663 0.000000
R while1 2175 10074.709060 1019 120
10074.709060 10075.915495 0.000000

So you can see in the latter case, it becomes difficult to see which
task belongs to which group.

The group names are also missing from per-CPU rq information. Hence in
the above example of 2 groups, I see 2 blocks of data for 2 cfs_rqs,
but it is not possible to know which group they represent.

Also, with tg_shares_up improvements, the leaf cfs_rqs are maintained
on rq->leaf_cfs_rq_list only if they carry any load. But the code to
display cfs_rq information for sched_debug isn't updated and hence
information from a few cfs_rqs are missing from sched_debug.

$ grep cfs_rq sched_debug-2.6.37-rc5
cfs_rq[0]:/2
cfs_rq[0]:/1
cfs_rq[0]:/
cfs_rq[1]:/2
cfs_rq[1]:/1
cfs_rq[1]:/
cfs_rq[2]:/2
cfs_rq[2]:/1
cfs_rq[2]:/
cfs_rq[3]:/2
cfs_rq[3]:/1
cfs_rq[3]:/
cfs_rq[4]:/2
cfs_rq[4]:/1
cfs_rq[4]:/
cfs_rq[5]:/2
cfs_rq[5]:/1
cfs_rq[5]:/
cfs_rq[6]:/2
cfs_rq[6]:/1
cfs_rq[6]:/
cfs_rq[7]:/2
cfs_rq[7]:/1
cfs_rq[7]:/
cfs_rq[8]:/2
cfs_rq[8]:/1
cfs_rq[8]:/
cfs_rq[9]:/2
cfs_rq[9]:/1
cfs_rq[9]:/
cfs_rq[10]:/2
cfs_rq[10]:/1
cfs_rq[10]:/
cfs_rq[11]:/2
cfs_rq[11]:/1
cfs_rq[11]:/
cfs_rq[12]:/2
cfs_rq[12]:/1
cfs_rq[12]:/
cfs_rq[13]:/2
cfs_rq[13]:/1
cfs_rq[13]:/
cfs_rq[14]:/2
cfs_rq[14]:/1
cfs_rq[14]:/
cfs_rq[15]:/2
cfs_rq[15]:/1
cfs_rq[15]:/

$ grep cfs_rq sched_debug-2.6.37-rc5-tip
cfs_rq[0]:
cfs_rq[0]:
cfs_rq[1]:
cfs_rq[2]:
cfs_rq[3]:
cfs_rq[4]:
cfs_rq[4]:
cfs_rq[5]:
cfs_rq[5]:
cfs_rq[6]:
cfs_rq[7]:
cfs_rq[8]:
cfs_rq[9]:
cfs_rq[10]:
cfs_rq[11]:
cfs_rq[11]:
cfs_rq[12]:
cfs_rq[12]:
cfs_rq[13]:
cfs_rq[13]:
cfs_rq[14]:
cfs_rq[14]:
cfs_rq[15]:
cfs_rq[15]:

Regards,
Bharata.
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Next message: Dan Carpenter: "[patch -next] power/gpio-charger: check for kzalloc() failure"
Previous message: graalfs: "[patch 0/4] OProfile support for System z's hardware sampling"
In reply to: Oleg Nesterov: "Re: [tip:sched/core] sched: Add 'autogroup' scheduling feature:automated per session task groups"
Next in thread: Peter Zijlstra: "Re: [tip:sched/core] sched: Add 'autogroup' scheduling feature:automated per session task groups"
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