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SubjectRe: [PATCH 05/10] cgroups: Ability to stop res charge propagation on bounded ancestor
On Mon, Oct 03, 2011 at 09:07:07PM +0200, Frederic Weisbecker wrote:
> Moving a task from a cgroup to another may require to substract
> its resource charge from the old cgroup and add it to the new one.
>
> For this to happen, the uncharge/charge propagation can just stop
> when we reach the common ancestor for the two cgroups. Further
> the performance reasons, we also want to avoid to temporarily
> overload the common ancestors with a non-accurate resource
> counter usage if we charge first the new cgroup and uncharge the
> old one thereafter. This is going to be a requirement for the coming
> max number of task subsystem.
>
> To solve this, provide a pair of new API that can charge/uncharge
> a resource counter until we reach a given ancestor.
>
> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
> Acked-by: Paul Menage <paul@paulmenage.org>

Acked-by: Kirill A. Shutemov <kirill@shutemov.name>

> Cc: Li Zefan <lizf@cn.fujitsu.com>
> Cc: Johannes Weiner <hannes@cmpxchg.org>
> Cc: Aditya Kali <adityakali@google.com>
> Cc: Oleg Nesterov <oleg@redhat.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Kay Sievers <kay.sievers@vrfy.org>
> Cc: Tim Hockin <thockin@hockin.org>
> Cc: Tejun Heo <tj@kernel.org>
> Cc: Kirill A. Shutemov <kirill@shutemov.name>
> Cc: Containers <containers@lists.linux-foundation.org>
> ---
> Documentation/cgroups/resource_counter.txt | 18 +++++++++++++++++-
> include/linux/res_counter.h | 20 +++++++++++++++++---
> kernel/res_counter.c | 13 ++++++++-----
> 3 files changed, 42 insertions(+), 9 deletions(-)
>
> diff --git a/Documentation/cgroups/resource_counter.txt b/Documentation/cgroups/resource_counter.txt
> index 95b24d7..a2cd05b 100644
> --- a/Documentation/cgroups/resource_counter.txt
> +++ b/Documentation/cgroups/resource_counter.txt
> @@ -83,7 +83,15 @@ to work with it.
> res_counter->lock internally (it must be called with res_counter->lock
> held).
>
> - e. void res_counter_uncharge[_locked]
> + e. int res_counter_charge_until(struct res_counter *counter,
> + struct res_counter *limit, unsigned long val,
> + struct res_counter **limit_fail_at)
> +
> + The same as res_counter_charge(), but the charge propagation to
> + the hierarchy stops at the limit given in the "limit" parameter.
> +
> +
> + f. void res_counter_uncharge[_locked]
> (struct res_counter *rc, unsigned long val)
>
> When a resource is released (freed) it should be de-accounted
> @@ -92,6 +100,14 @@ to work with it.
>
> The _locked routines imply that the res_counter->lock is taken.
>
> +
> + g. void res_counter_uncharge_until(struct res_counter *counter,
> + struct res_counter *limit,
> + unsigned long val)
> +
> + The same as res_counter_charge, but the uncharge propagation to
> + the hierarchy stops at the limit given in the "limit" parameter.
> +
> 2.1 Other accounting routines
>
> There are more routines that may help you with common needs, like
> diff --git a/include/linux/res_counter.h b/include/linux/res_counter.h
> index 109d118..de4ba29 100644
> --- a/include/linux/res_counter.h
> +++ b/include/linux/res_counter.h
> @@ -117,8 +117,16 @@ void res_counter_init(struct res_counter *counter, struct res_counter *parent);
>
> int __must_check res_counter_charge_locked(struct res_counter *counter,
> unsigned long val);
> -int __must_check res_counter_charge(struct res_counter *counter,
> - unsigned long val, struct res_counter **limit_fail_at);
> +int __must_check res_counter_charge_until(struct res_counter *counter,
> + struct res_counter *limit,
> + unsigned long val,
> + struct res_counter **limit_fail_at);
> +static inline int __must_check
> +res_counter_charge(struct res_counter *counter, unsigned long val,
> + struct res_counter **limit_fail_at)
> +{
> + return res_counter_charge_until(counter, NULL, val, limit_fail_at);
> +}
>
> /*
> * uncharge - tell that some portion of the resource is released
> @@ -131,7 +139,13 @@ int __must_check res_counter_charge(struct res_counter *counter,
> */
>
> void res_counter_uncharge_locked(struct res_counter *counter, unsigned long val);
> -void res_counter_uncharge(struct res_counter *counter, unsigned long val);
> +void res_counter_uncharge_until(struct res_counter *counter,
> + struct res_counter *limit, unsigned long val);
> +static inline void res_counter_uncharge(struct res_counter *counter,
> + unsigned long val)
> +{
> + res_counter_uncharge_until(counter, NULL, val);
> +}
>
> /**
> * res_counter_margin - calculate chargeable space of a counter
> diff --git a/kernel/res_counter.c b/kernel/res_counter.c
> index 37abf4e..0cc9c7e 100644
> --- a/kernel/res_counter.c
> +++ b/kernel/res_counter.c
> @@ -35,8 +35,9 @@ int res_counter_charge_locked(struct res_counter *counter, unsigned long val)
> return 0;
> }
>
> -int res_counter_charge(struct res_counter *counter, unsigned long val,
> - struct res_counter **limit_fail_at)
> +int res_counter_charge_until(struct res_counter *counter,
> + struct res_counter *limit, unsigned long val,
> + struct res_counter **limit_fail_at)
> {
> int ret;
> unsigned long flags;
> @@ -44,7 +45,7 @@ int res_counter_charge(struct res_counter *counter, unsigned long val,
>
> *limit_fail_at = NULL;
> local_irq_save(flags);
> - for (c = counter; c != NULL; c = c->parent) {
> + for (c = counter; c != limit; c = c->parent) {
> spin_lock(&c->lock);
> ret = res_counter_charge_locked(c, val);
> spin_unlock(&c->lock);
> @@ -74,13 +75,15 @@ void res_counter_uncharge_locked(struct res_counter *counter, unsigned long val)
> counter->usage -= val;
> }
>
> -void res_counter_uncharge(struct res_counter *counter, unsigned long val)
> +void res_counter_uncharge_until(struct res_counter *counter,
> + struct res_counter *limit,
> + unsigned long val)
> {
> unsigned long flags;
> struct res_counter *c;
>
> local_irq_save(flags);
> - for (c = counter; c != NULL; c = c->parent) {
> + for (c = counter; c != limit; c = c->parent) {
> spin_lock(&c->lock);
> res_counter_uncharge_locked(c, val);
> spin_unlock(&c->lock);
> --
> 1.7.5.4
>

--
Kirill A. Shutemov


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