Re: [PATCH 05/10] Make total_forks per-cgroup

[Glauber Costa]

On 10/05/2011 01:05 PM, Peter Zijlstra wrote:
> On Sun, 2011-10-02 at 23:21 +0400, Glauber Costa wrote:
> > This patch counts the total number of forks per-cgroup.
> > The information is propagated to the parent, so the total
> > number of forks in the system, is the parent cgroup's one.
> >
> > To achieve that, total_forks is made per-cpu. There is no
> > particular reason to do that, but by doing this, we are
> > able to bundle it inside the cpustat structure already
> > present.
>
> I think fweisbec is also doing something with forks and cgroups.

I am all ears...

Frederic, does it conflict with what you're doing ?

> > Signed-off-by: Glauber Costa<glommer@xxxxxxxxxxxxx>
> > ---
> >   include/linux/kernel_stat.h |    1 +
> >   include/linux/sched.h       |    1 +
> >   kernel/fork.c               |    7 ++-----
> >   kernel/sched.c              |    9 ++++++++-
> >   4 files changed, 12 insertions(+), 6 deletions(-)
> >
> > diff --git a/include/linux/kernel_stat.h b/include/linux/kernel_stat.h
> > index 71a69a0..9fb0dda 100644
> > --- a/include/linux/kernel_stat.h
> > +++ b/include/linux/kernel_stat.h
> > @@ -29,6 +29,7 @@ enum cpu_usage_stat {
> >   	GUEST_NICE,
> >   	IDLE_BASE,
> >   	IOWAIT_BASE,
> > +	TOTAL_FORKS,
> >   	NR_STATS,
> >   };
> >
> > diff --git a/include/linux/sched.h b/include/linux/sched.h
> > index 64c5ba5..4ba9dde 100644
> > --- a/include/linux/sched.h
> > +++ b/include/linux/sched.h
> > @@ -2716,6 +2716,7 @@ struct cgroup;
> >   struct cftype;
> >   int cpu_cgroup_proc_stat(struct cgroup *cgrp, struct cftype *cft,
> >   			 struct seq_file *p);
> > +void task_group_new_fork(struct task_struct *p);
> >   #endif /* __KERNEL__ */
> >
> >   #endif
> > diff --git a/kernel/fork.c b/kernel/fork.c
> > index 8e6b6f4..ec2b729 100644
> > --- a/kernel/fork.c
> > +++ b/kernel/fork.c
> > @@ -76,10 +76,6 @@
> >
> >   #include<trace/events/sched.h>
> >
> > -/*
> > - * Protected counters by write_lock_irq(&tasklist_lock)
> > - */
> > -unsigned long total_forks;	/* Handle normal Linux uptimes. */
> >   int nr_threads;			/* The idle threads do not count.. */
> >
> >   int max_threads;		/* tunable limit on nr_threads */
> > @@ -1372,7 +1368,8 @@ static struct task_struct *copy_process(unsigned long clone_flags,
> >   		nr_threads++;
> >   	}
> >
> > -	total_forks++;
> > +	task_group_new_fork(p);
> > +
> >   	spin_unlock(&current->sighand->siglock);
> >   	write_unlock_irq(&tasklist_lock);
> >   	proc_fork_connector(p);
> > diff --git a/kernel/sched.c b/kernel/sched.c
> > index 89d2248..5a8181e 100644
> > --- a/kernel/sched.c
> > +++ b/kernel/sched.c
> > @@ -691,6 +691,11 @@ static inline void task_group_account_field(struct task_struct *p,
> >   }
> >   #endif /* CONFIG_CGROUP_SCHED */
> >
> > +void task_group_new_fork(struct task_struct *p)
> > +{
> > +	task_group_account_field(p, 1, TOTAL_FORKS);
> > +}
> > +
> >   static void update_rq_clock_task(struct rq *rq, s64 delta);
> >
> >   static void update_rq_clock(struct rq *rq)
> > @@ -9161,6 +9166,7 @@ int cpu_cgroup_proc_stat(struct cgroup *cgrp, struct cftype *cft,
> >   	u64 guest, guest_nice;
> >   	u64 sum = 0;
> >   	u64 sum_softirq = 0;
> > +	u64 total_forks = 0;
> >   	unsigned int per_softirq_sums[NR_SOFTIRQS] = {0};
> >   	struct timespec boottime;
> >   #ifdef CONFIG_CGROUP_SCHED
> > @@ -9201,6 +9207,7 @@ int cpu_cgroup_proc_stat(struct cgroup *cgrp, struct cftype *cft,
> >   		steal += kstat->cpustat[STEAL];
> >   		guest += kstat->cpustat[GUEST];
> >   		guest_nice += kstat->cpustat[GUEST_NICE];
> > +		total_forks += kstat->cpustat[TOTAL_FORKS];
> >   		sum += kstat_cpu_irqs_sum(i);
> >   		sum += arch_irq_stat_cpu(i);
> >
> > @@ -9272,7 +9279,7 @@ int cpu_cgroup_proc_stat(struct cgroup *cgrp, struct cftype *cft,
> >   	seq_printf(p,
> >   		"\nctxt %llu\n"
> >   		"btime %lu\n"
> > -		"processes %lu\n"
> > +		"processes %llu\n"
> >   		"procs_running %lu\n"
> >   		"procs_blocked %lu\n",
> >   		nr_context_switches(),

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