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On 07/16/2012 05:16 PM, Michael Wang wrote:
> From: Michael Wang <wangyun@xxxxxxxxxxxxxxxxxx>
>
> This patch is trying to provide a way for user to dynamically change
> the behaviour of load balance by setting flags of schedule domain.
>
> Currently it's rely on cpu cgroup and only SD_LOAD_BALANCE was
> implemented, usage:
>
> 1. /sys/fs/cgroup/domain/domain.config_level
> the default config_level is 0, which means we currenlty configure
> the sibling domain for all cpus, we can use:
> echo 'number' > /sys/fs/cgroup/domain/domain.config_level
> to change the level.
>
> 2. /sys/fs/cgroup/domain/domain.topology
> this will help to show the SD_LOAD_BALANCE status of all the cpu's
> all domain level, we can use:
> cat /sys/fs/cgroup/domain/domain.topology
>
> 3. /sys/fs/cgroup/domain/domain.SD_LOAD_BALANCE
> this will help us to change the bit SD_LOAD_BALANCE in the flag of
> schedule domain on level 'config_level', we can use:
> echo 1 > /sys/fs/cgroup/domain/domain.SD_LOAD_BALANCE
> to enable this bit, and:
> echo 0 > /sys/fs/cgroup/domain/domain.SD_LOAD_BALANCE
> to disable it.
>
> It may not works well now(may be even not work at all as I can't see any
> changes on my server even after disabled SD_LOAD_BALANCE on all domains),
> but it is interesting and should be liked by some people who desire a
> way to 'kill' the load balance by their own hands if we can implement it.
>
> Comments and questions are very welcomed ;-)
>
> Signed-off-by: Michael Wang <wangyun@xxxxxxxxxxxxxxxxxx>
> ---
> include/linux/cgroup_subsys.h | 1 +
> kernel/sched/core.c | 143 +++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 144 insertions(+), 0 deletions(-)
>
> diff --git a/include/linux/cgroup_subsys.h b/include/linux/cgroup_subsys.h
> index 0bd390c..25eb842 100644
> --- a/include/linux/cgroup_subsys.h
> +++ b/include/linux/cgroup_subsys.h
> @@ -21,6 +21,7 @@ SUBSYS(debug)
>
> #ifdef CONFIG_CGROUP_SCHED
> SUBSYS(cpu_cgroup)
> +SUBSYS(domain_cgroup)
> #endif
>
> /* */
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index 3987b9d..544bf78 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -8423,6 +8423,149 @@ struct cgroup_subsys cpu_cgroup_subsys = {
> .early_init = 1,
> };
>
> +static struct cgroup_subsys_state domain_cgroup_css;
> +static struct cgroup_subsys_state *domain_cgroup_create(struct cgroup *cgrp)
> +{
> + if (!cgrp->parent) {
> + /* This is early initialization for the top cgroup */
> + return &domain_cgroup_css;
> + }
> +
> + return ERR_PTR(-EPERM);
> +}
> +
> +static void domain_cgroup_destroy(struct cgroup *cgrp)
> +{
> + return;
> +}
> +
> +static int domain_cgroup_can_attach(struct cgroup *cgrp,
> + struct cgroup_taskset *tset)
> +{
> + return -EINVAL;
> +}
> +
> +static void domain_cgroup_attach(struct cgroup *cgrp,
> + struct cgroup_taskset *tset)
> +{
> + return;
> +}
> +
> +static void domain_cgroup_exit(struct cgroup *cgrp,
> + struct cgroup *old_cgrp,
> + struct task_struct *task)
> +{
> + return;
> +}
> +
> +static int domain_config_level;
> +
> +static int domain_cl_write_u64(struct cgroup *cgrp,
> + struct cftype *cftype,
> + u64 shareval)
> +{
> + domain_config_level = shareval;
> + return 0;
> +}
> +
> +static u64 domain_cl_read_u64(struct cgroup *cgrp, struct cftype *cft)
> +{
> + return (u64)domain_config_level;
> +}
> +
> +static int domain_slb_write_u64(struct cgroup *cgrp,
> + struct cftype *cftype,
> + u64 shareval)
> +{
> + int cpu;
> + struct sched_domain *sd;
> + if (shareval != 0 && shareval != 1)
> + return -EINVAL;
> +
> + mutex_lock(&sched_domains_mutex);
> + for_each_cpu(cpu, cpu_active_mask) {
> + for (sd = cpu_rq(cpu)->sd; sd; sd = sd->parent) {
> + if (sd->level == domain_config_level) {
> + if (shareval)
> + sd->flags |= SD_LOAD_BALANCE;
> + else
> + sd->flags &= ~SD_LOAD_BALANCE;
> + }
> + }
> + }
> + mutex_unlock(&sched_domains_mutex);
> + return 0;
> +}
> +
> +static u64 domain_slb_read_u64(struct cgroup *cgrp, struct cftype *cft)
> +{
> + int cpu, ret = 0;
> + struct sched_domain *sd;
> + mutex_lock(&sched_domains_mutex);
> + for_each_cpu(cpu, cpu_active_mask) {
> + for (sd = cpu_rq(cpu)->sd; sd; sd = sd->parent) {
> + if (sd->level == domain_config_level) {
> + if (sd->flags & SD_LOAD_BALANCE)
> + ret = 1;
> + goto out;
> + }
> + }
> + }
> +out:
> + mutex_unlock(&sched_domains_mutex);
> + return ret;
> +}
> +
> +static int domain_topology_show(struct cgroup *cgrp,
> + struct cftype *cft,
> + struct cgroup_map_cb *cb)
> +{
> + int cpu;
> + struct sched_domain *sd;
> + mutex_lock(&sched_domains_mutex);
> + for_each_cpu(cpu, cpu_active_mask) {
> + cb->fill(cb, "cpu", cpu);
> + for (sd = cpu_rq(cpu)->sd; sd; sd = sd->parent) {
> + cb->fill(cb, "\tlevel", sd->level);
> + cb->fill(cb, "\t\tSD_LOAD_BALANCE",
> + sd->flags & SD_LOAD_BALANCE);
> + }
> + }
> + mutex_unlock(&sched_domains_mutex);
> +
> + return 0;
> +}
> +
> +static struct cftype domain_files[] = {
> + {
> + .name = "config_level",
> + .read_u64 = domain_cl_read_u64,
> + .write_u64 = domain_cl_write_u64,
> + },
> + {
> + .name = "SD_LOAD_BALANCE",
> + .read_u64 = domain_slb_read_u64,
> + .write_u64 = domain_slb_write_u64,
> + },
> + {
> + .name = "topology",
> + .read_map = domain_topology_show,
> + },
> + { } /* terminate */
> +};
> +
> +struct cgroup_subsys domain_cgroup_subsys = {
> + .name = "domain",
> + .create = domain_cgroup_create,
> + .destroy = domain_cgroup_destroy,
> + .can_attach = domain_cgroup_can_attach,
> + .attach = domain_cgroup_attach,
> + .exit = domain_cgroup_exit,
> + .subsys_id = domain_cgroup_subsys_id,
> + .base_cftypes = domain_files,
> + .early_init = 1,
> +};
> +
> #endif /* CONFIG_CGROUP_SCHED */
>
> #ifdef CONFIG_CGROUP_CPUACCT
>
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