diff options
| author | Colin Cross <ccross@android.com> | 2010-11-23 21:37:04 -0800 |
|---|---|---|
| committer | Jonas ABERG <jonas.aberg@stericsson.com> | 2011-04-01 13:30:52 +0200 |
| commit | b0071d59dfe203a7d7364588b4fcf109167efb0f (patch) | |
| tree | 7e8700f1010fcf9b32c2e7f3b63facb56919d588 /include | |
| parent | 54eefaf5f25ef9a531e37b30ec90d2d567ed65d0 (diff) | |
cgroup: Remove call to synchronize_rcu in cgroup_attach_task
synchronize_rcu can be very expensive, averaging 100 ms in
some cases. In cgroup_attach_task, it is used to prevent
a task->cgroups pointer dereferenced in an RCU read side
critical section from being invalidated, by delaying the
call to put_css_set until after an RCU grace period.
To avoid the call to synchronize_rcu, make the put_css_set
call rcu-safe by moving the deletion of the css_set links
into free_css_set_work, scheduled by the rcu callback
free_css_set_rcu.
The decrement of the cgroup refcount is no longer
synchronous with the call to put_css_set, which can result
in the cgroup refcount staying positive after the last call
to cgroup_attach_task returns. To allow the cgroup to be
deleted with cgroup_rmdir synchronously after
cgroup_attach_task, have rmdir check the refcount of all
associated css_sets. If cgroup_rmdir is called on a cgroup
for which the css_sets all have refcount zero but the
cgroup refcount is nonzero, reuse the rmdir waitqueue to
block the rmdir until free_css_set_work is called.
Signed-off-by: Colin Cross <ccross@android.com>
Change-Id: If12ca64cd978752a8e3a37a6230fb0bd485f63f9
Reviewed-on: http://gerrit.lud.stericsson.com/gerrit/19515
Tested-by: Piotr TOMASZEWSKI <piotr.tomaszewski@stericsson.com>
Reviewed-by: Jonas ABERG <jonas.aberg@stericsson.com>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/cgroup.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index eb56ba0a753..e82e721e10b 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -275,6 +275,7 @@ struct css_set { /* For RCU-protected deletion */ struct rcu_head rcu_head; + struct work_struct work; }; /* |