diff options
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/cgroup-defs.h | 17 | ||||
| -rw-r--r-- | include/linux/sched/signal.h | 4 |
2 files changed, 20 insertions, 1 deletions
diff --git a/include/linux/cgroup-defs.h b/include/linux/cgroup-defs.h index ff3c7d0e3e01..93318fce31f3 100644 --- a/include/linux/cgroup-defs.h +++ b/include/linux/cgroup-defs.h @@ -91,6 +91,12 @@ enum { * cgroup_threadgroup_rwsem. This makes hot path operations such as * forks and exits into the slow path and more expensive. * + * Alleviate the contention between fork, exec, exit operations and + * writing to cgroup.procs by taking a per threadgroup rwsem instead of + * the global cgroup_threadgroup_rwsem. Fork and other operations + * from threads in different thread groups no longer contend with + * writing to cgroup.procs. + * * The static usage pattern of creating a cgroup, enabling controllers, * and then seeding it with CLONE_INTO_CGROUP doesn't require write * locking cgroup_threadgroup_rwsem and thus doesn't benefit from @@ -146,6 +152,9 @@ enum cgroup_attach_lock_mode { /* When pid=0 && threadgroup=false, see comments in cgroup_procs_write_start */ CGRP_ATTACH_LOCK_NONE, + + /* When favordynmods is on, see comments above CGRP_ROOT_FAVOR_DYNMODS */ + CGRP_ATTACH_LOCK_PER_THREADGROUP, }; /* @@ -846,6 +855,7 @@ struct cgroup_subsys { }; extern struct percpu_rw_semaphore cgroup_threadgroup_rwsem; +extern bool cgroup_enable_per_threadgroup_rwsem; struct cgroup_of_peak { unsigned long value; @@ -857,11 +867,14 @@ struct cgroup_of_peak { * @tsk: target task * * Allows cgroup operations to synchronize against threadgroup changes - * using a percpu_rw_semaphore. + * using a global percpu_rw_semaphore and a per threadgroup rw_semaphore when + * favordynmods is on. See the comment above CGRP_ROOT_FAVOR_DYNMODS definition. */ static inline void cgroup_threadgroup_change_begin(struct task_struct *tsk) { percpu_down_read(&cgroup_threadgroup_rwsem); + if (cgroup_enable_per_threadgroup_rwsem) + down_read(&tsk->signal->cgroup_threadgroup_rwsem); } /** @@ -872,6 +885,8 @@ static inline void cgroup_threadgroup_change_begin(struct task_struct *tsk) */ static inline void cgroup_threadgroup_change_end(struct task_struct *tsk) { + if (cgroup_enable_per_threadgroup_rwsem) + up_read(&tsk->signal->cgroup_threadgroup_rwsem); percpu_up_read(&cgroup_threadgroup_rwsem); } diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h index 1ef1edbaaf79..7d6449982822 100644 --- a/include/linux/sched/signal.h +++ b/include/linux/sched/signal.h @@ -226,6 +226,10 @@ struct signal_struct { struct tty_audit_buf *tty_audit_buf; #endif +#ifdef CONFIG_CGROUPS + struct rw_semaphore cgroup_threadgroup_rwsem; +#endif + /* * Thread is the potential origin of an oom condition; kill first on * oom |