On 11/23/2010 09:37 PM, Colin Cross wrote: > Changes the meaning of CGRP_RELEASABLE to be set on any cgroup > that has ever had a task or cgroup in it, or had css_get called > on it. The bit is set in cgroup_attach_task, cgroup_create, > and __css_get. It is not necessary to set the bit in > cgroup_fork, as the task is either in the root cgroup, in > which can never be released, or the task it was forked from > already set the bit in croup_attach_task. > > Signed-off-by: Colin Cross <[email protected]> > --- > include/linux/cgroup.h | 12 +-------- > kernel/cgroup.c | 54 ++++++++++++++++++++--------------------------- > 2 files changed, 25 insertions(+), 41 deletions(-) > > diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h > index ed4ba11..9e13078 100644 > --- a/include/linux/cgroup.h > +++ b/include/linux/cgroup.h > @@ -84,12 +84,6 @@ enum { > CSS_REMOVED, /* This CSS is dead */ > }; > > -/* Caller must verify that the css is not for root cgroup */ > -static inline void __css_get(struct cgroup_subsys_state *css, int count) > -{ > - atomic_add(count, &css->refcnt); > -} > - > /* > * Call css_get() to hold a reference on the css; it can be used > * for a reference obtained via: > @@ -97,6 +91,7 @@ static inline void __css_get(struct cgroup_subsys_state > *css, int count) > * - task->cgroups for a locked task > */ > > +extern void __css_get(struct cgroup_subsys_state *css, int count); > static inline void css_get(struct cgroup_subsys_state *css) > { > /* We don't need to reference count the root state */ > @@ -143,10 +138,7 @@ static inline void css_put(struct cgroup_subsys_state > *css) > enum { > /* Control Group is dead */ > CGRP_REMOVED, > - /* > - * Control Group has previously had a child cgroup or a task, > - * but no longer (only if CGRP_NOTIFY_ON_RELEASE is set) > - */ > + /* Control Group has ever had a child cgroup or a task */ > CGRP_RELEASABLE, > /* Control Group requires release notifications to userspace */ > CGRP_NOTIFY_ON_RELEASE, > diff --git a/kernel/cgroup.c b/kernel/cgroup.c > index 66a416b..34e855e 100644 > --- a/kernel/cgroup.c > +++ b/kernel/cgroup.c > @@ -338,7 +338,15 @@ static void free_css_set_rcu(struct rcu_head *obj) > * compiled into their kernel but not actually in use */ > static int use_task_css_set_links __read_mostly; > > -static void __put_css_set(struct css_set *cg, int taskexit) > +/* > + * refcounted get/put for css_set objects > + */ > +static inline void get_css_set(struct css_set *cg) > +{ > + atomic_inc(&cg->refcount); > +} > + > +static void put_css_set(struct css_set *cg) > { > struct cg_cgroup_link *link; > struct cg_cgroup_link *saved_link; > @@ -364,12 +372,8 @@ static void __put_css_set(struct css_set *cg, int > taskexit) > struct cgroup *cgrp = link->cgrp; > list_del(&link->cg_link_list); > list_del(&link->cgrp_link_list); > - if (atomic_dec_and_test(&cgrp->count) && > - notify_on_release(cgrp)) { > - if (taskexit) > - set_bit(CGRP_RELEASABLE, &cgrp->flags); > + if (atomic_dec_and_test(&cgrp->count)) > check_for_release(cgrp); > - } > > kfree(link); > } > @@ -379,24 +383,6 @@ static void __put_css_set(struct css_set *cg, int > taskexit) > } > > /* > - * refcounted get/put for css_set objects > - */ > -static inline void get_css_set(struct css_set *cg) > -{ > - atomic_inc(&cg->refcount); > -} > - > -static inline void put_css_set(struct css_set *cg) > -{ > - __put_css_set(cg, 0); > -} > - > -static inline void put_css_set_taskexit(struct css_set *cg) > -{ > - __put_css_set(cg, 1); > -} > - > -/* > * compare_css_sets - helper function for find_existing_css_set(). > * @cg: candidate css_set being tested > * @old_cg: existing css_set for a task > @@ -1801,7 +1787,7 @@ int cgroup_attach_task(struct cgroup *cgrp, struct > task_struct *tsk) > if (ss->attach) > ss->attach(ss, cgrp, oldcgrp, tsk, false); > } > - set_bit(CGRP_RELEASABLE, &oldcgrp->flags); > + set_bit(CGRP_RELEASABLE, &cgrp->flags); > synchronize_rcu(); > put_css_set(cg); > > @@ -3427,6 +3413,8 @@ static long cgroup_create(struct cgroup *parent, struct > dentry *dentry, > if (err < 0) > goto err_remove; > > + set_bit(CGRP_RELEASABLE, &parent->flags); > + > /* The cgroup directory was pre-locked for us */ > BUG_ON(!mutex_is_locked(&cgrp->dentry->d_inode->i_mutex)); > > @@ -3645,7 +3633,6 @@ again: > cgroup_d_remove_dir(d); > dput(d); > > - set_bit(CGRP_RELEASABLE, &parent->flags); > check_for_release(parent); > > /* > @@ -4240,7 +4227,7 @@ void cgroup_exit(struct task_struct *tsk, int > run_callbacks) > tsk->cgroups = &init_css_set; > task_unlock(tsk); > if (cg) > - put_css_set_taskexit(cg); > + put_css_set(cg); > } > > /** > @@ -4410,6 +4397,14 @@ static void check_for_release(struct cgroup *cgrp) > } > > /* Caller must verify that the css is not for root cgroup */ > +void __css_get(struct cgroup_subsys_state *css, int count) > +{ > + atomic_add(count, &css->refcnt); > + set_bit(CGRP_RELEASABLE, &css->cgroup->flags); > +} > +EXPORT_SYMBOL_GPL(__css_get); > + > +/* Caller must verify that the css is not for root cgroup */ > void __css_put(struct cgroup_subsys_state *css, int count) > { > struct cgroup *cgrp = css->cgroup; > @@ -4417,10 +4412,7 @@ void __css_put(struct cgroup_subsys_state *css, int > count) > rcu_read_lock(); > val = atomic_sub_return(count, &css->refcnt); > if (val == 1) { > - if (notify_on_release(cgrp)) { > - set_bit(CGRP_RELEASABLE, &cgrp->flags); > - check_for_release(cgrp); > - } > + check_for_release(cgrp); > cgroup_wakeup_rmdir_waiter(cgrp); > } > rcu_read_unlock();
Tested-by: Mike Bohan <[email protected]> I'm responding on Mike's behalf and adding him to this thread. This patch improves launch time of a test app from ~700ms to ~250ms on MSM, with much lower variance across tests. We also see UI latency improvements, but have not quantified the gains. - Bryan -- Sent by an employee of the Qualcomm Innovation Center, Inc. The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum. _______________________________________________ Containers mailing list [email protected] https://lists.linux-foundation.org/mailman/listinfo/containers _______________________________________________ Devel mailing list [email protected] https://openvz.org/mailman/listinfo/devel
