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SubjectRe: [RFC PATCH 2/2] cgroup/freezer: add per freezer duty ratio control
On Wed, Dec 01, 2010 at 11:00:12AM -0800, jacob.jun.pan@linux.intel.com wrote:
> From: Jacob Pan <jacob.jun.pan@linux.intel.com>
>
> Freezer subsystem is used to manage batch jobs which can start
> stop at the same time. However, sometime it is desirable to let
> the kernel manage the freezer state automatically with a given
> duty ratio.
> For example, if we want to reduce the time that backgroup apps
> are allowed to run we can put them into a freezer subsystem and
> set the kernel to turn them THAWED/FROZEN at given duty ratio.
>
> This patch introduces two file nodes
> freezer.duty_ratio and freezer.period_ms
> Usage example, set period to be 50 ms and frozen duty ratio 90%
> [root@localhost aoa]# echo 90 > freezer.duty_ratio
> [root@localhost aoa]# echo 50 > freezer.period_ms
>
> Each freezer will be controlled by its own kernel thread which is
> in sleep unless there is a state/parameter change.
>
> Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
> ---
> kernel/cgroup_freezer.c | 157 ++++++++++++++++++++++++++++++++++++++++++++++-
> 1 files changed, 155 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/cgroup_freezer.c b/kernel/cgroup_freezer.c
> index e7bebb7..07941fa 100644
> --- a/kernel/cgroup_freezer.c
> +++ b/kernel/cgroup_freezer.c
> @@ -21,6 +21,7 @@
> #include <linux/uaccess.h>
> #include <linux/freezer.h>
> #include <linux/seq_file.h>
> +#include <linux/kthread.h>
>
> enum freezer_state {
> CGROUP_THAWED = 0,
> @@ -28,12 +29,23 @@ enum freezer_state {
> CGROUP_FROZEN,
> };
>
> +struct freezer_duty {
> + u32 ratio; /* percentage of time allowed to run */
> + u32 period; /* period in seconds */

miliseconds, I guess.
And why do you use u32, not int?

> +};
> +
> struct freezer {
> struct cgroup_subsys_state css;
> enum freezer_state state;
> + struct freezer_duty duty;
> + struct task_struct *fkh;
> spinlock_t lock; /* protects _writes_ to state */
> };
>
> +static struct task_struct *freezer_task;
> +static int try_to_freeze_cgroup(struct cgroup *cgroup, struct freezer *freezer);
> +static void unfreeze_cgroup(struct cgroup *cgroup, struct freezer *freezer);
> +
> static inline struct freezer *cgroup_freezer(
> struct cgroup *cgroup)
> {
> @@ -63,6 +75,34 @@ int cgroup_freezing_or_frozen(struct task_struct *task)
> return result;
> }
>
> +static DECLARE_WAIT_QUEUE_HEAD(freezer_wait);
> +
> +static int freezer_kh(void *data)
> +{
> + struct cgroup *cgroup = (struct cgroup *)data;
> + struct freezer *freezer = cgroup_freezer(cgroup);
> +
> + do {
> + if (freezer->duty.ratio < 100 && freezer->duty.ratio >= 0 &&
> + freezer->duty.period) {
> + if (try_to_freeze_cgroup(cgroup, freezer))
> + pr_info("cannot freeze\n");
> + msleep(freezer->duty.period * freezer->duty.ratio);
> + unfreeze_cgroup(cgroup, freezer);
> + msleep(freezer->duty.period *
> + (100 - freezer->duty.ratio));
> + } else if (freezer->duty.ratio == 100) {
> + if (try_to_freeze_cgroup(cgroup, freezer))
> + pr_info("cannot freeze\n");
> + sleep_on(&freezer_wait);
> + } else {
> + sleep_on(&freezer_wait);
> + pr_debug("freezer thread wake up\n");
> + }
> + } while (!kthread_should_stop());
> + return 0;
> +}
> +
> /*
> * cgroups_write_string() limits the size of freezer state strings to
> * CGROUP_LOCAL_BUFFER_SIZE
> @@ -150,7 +190,11 @@ static struct cgroup_subsys_state *freezer_create(struct cgroup_subsys *ss,
> static void freezer_destroy(struct cgroup_subsys *ss,
> struct cgroup *cgroup)
> {
> - kfree(cgroup_freezer(cgroup));
> + struct freezer *freezer;
> +
> + freezer = cgroup_freezer(cgroup);
> + kthread_stop(freezer->fkh);
> + kfree(freezer);
> }
>
> /*
> @@ -282,6 +326,51 @@ static int freezer_read(struct cgroup *cgroup, struct cftype *cft,
> return 0;
> }
>
> +static int freezer_read_duty_ratio(struct cgroup *cgroup, struct cftype *cft,
> + struct seq_file *m)
> +{
> + struct freezer *freezer;
> + u32 duty_ratio;
> + char result[8];
> +
> + if (!cgroup_lock_live_group(cgroup))
> + return -ENODEV;
> +
> + freezer = cgroup_freezer(cgroup);
> + spin_lock_irq(&freezer->lock);
> + duty_ratio = freezer->duty.ratio;
> + spin_unlock_irq(&freezer->lock);
> + cgroup_unlock();
> +
> + sprintf(result, "%d", duty_ratio);
> + seq_puts(m, result);
> + seq_putc(m, '\n');
> + return 0;
> +}
> +
> +static int freezer_read_period(struct cgroup *cgroup, struct cftype *cft,
> + struct seq_file *m)
> +{
> + struct freezer *freezer;
> + u32 period;
> + char result[8];
> +
> + if (!cgroup_lock_live_group(cgroup))
> + return -ENODEV;
> +
> + freezer = cgroup_freezer(cgroup);
> + spin_lock_irq(&freezer->lock);
> + period = freezer->duty.period;
> + spin_unlock_irq(&freezer->lock);
> + cgroup_unlock();
> +
> + sprintf(result, "%d", period);
> + seq_puts(m, result);
> + seq_putc(m, '\n');
> +
> + return 0;
> +}
> +
> static int try_to_freeze_cgroup(struct cgroup *cgroup, struct freezer *freezer)
> {
> struct cgroup_iter it;
> @@ -368,19 +457,83 @@ static int freezer_write(struct cgroup *cgroup,
> return retval;
> }
>
> +static int freezer_write_duty_ratio(struct cgroup *cgroup,
> + struct cftype *cft,
> + const char *buffer)
> +{
> + struct freezer *freezer;
> + unsigned long ratio;
> +
> + if (strict_strtoul(buffer, 10, &ratio) < 0)
> + return -EINVAL;
> +
> + if (ratio > 100) {
> + pr_err("Out of range, ratio should be < 100\n");
> + return -EINVAL;
> + }
> +
> + freezer = cgroup_freezer(cgroup);
> + spin_lock_irq(&freezer->lock);
> + freezer->duty.ratio = ratio;
> + spin_unlock_irq(&freezer->lock);
> + wake_up(&freezer_wait);
> +
> + return 0;
> +}
> +
> +static int freezer_write_period(struct cgroup *cgroup,
> + struct cftype *cft,
> + const char *buffer)
> +{
> + struct freezer *freezer;
> +
> + freezer = cgroup_freezer(cgroup);
> + spin_lock_irq(&freezer->lock);
> + if (strict_strtoul(buffer, 10, &freezer->duty.period) < 0)
> + return -EINVAL;

spin_unlock_irq() is missed on error handling.

> + spin_unlock_irq(&freezer->lock);
> + wake_up(&freezer_wait);
> +
> + return 0;
> +}
> +
> static struct cftype files[] = {
> {
> .name = "state",
> .read_seq_string = freezer_read,
> .write_string = freezer_write,
> },
> + {
> + .name = "duty_ratio",
> + .read_seq_string = freezer_read_duty_ratio,
> + .write_string = freezer_write_duty_ratio,
> + },
> + {
> + .name = "period_ms",
> + .read_seq_string = freezer_read_period,
> + .write_string = freezer_write_period,
> + },
> };
>
> +#define FREEZER_KH_PREFIX "freezer_"
> static int freezer_populate(struct cgroup_subsys *ss, struct cgroup *cgroup)
> {
> + int ret = 0;
> + char thread_name[32];
> + struct freezer *freezer;
> +
> if (!cgroup->parent)
> return 0;
> - return cgroup_add_files(cgroup, ss, files, ARRAY_SIZE(files));
> +
> + freezer = cgroup_freezer(cgroup);
> + ret = cgroup_add_files(cgroup, ss, files, ARRAY_SIZE(files));
> +
> + snprintf(thread_name, 32, "%s%s", FREEZER_KH_PREFIX,
> + cgroup->dentry->d_name.name);
> + freezer->fkh = kthread_run(freezer_kh, (void *)cgroup, thread_name);
> + if (!IS_ERR(freezer_task))
> + return 0;
> + return ret;

Why do you create on freezer_populate, not on freezer_create?
And error handling is broken here.

> }
>
> struct cgroup_subsys freezer_subsys = {
> --
> 1.7.0.4
>
> _______________________________________________
> Containers mailing list
> Containers@lists.linux-foundation.org
> https://lists.linux-foundation.org/mailman/listinfo/containers

--
Kirill A. Shutemov


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