arno/linux-insides
1
0
Fork 0
mirror of https://github.com/0xAX/linux-insides.git synced 2024-12-21 22:28:08 +00:00
Code Issues Releases Wiki Activity

fix: ccs to css (cgroup subsystem stage)

Browse Source
This commit is contained in:
唐一 2017-09-02 12:04:58 +08:00
parent d0c8fc5c01
commit 0045771415
1 changed files with 3 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
Cgroups/cgroups1.md
View File

@ -275,7 +275,7 @@ struct cgroup_subsys {
}
```
Where for example `ccs_online` and `ccs_offline` callbacks are called after a cgroup successfully will complete all allocations and a cgroup will be before releasing respectively. The `early_init` flags marks subsystems which may/should be initialized early. The `id` and `name` fields represents unique identifier in the array of registered subsystems for a cgroup and `name` of a subsystem respectively. The last - `root` fields represents pointer to the root of of a cgroup hierarchy.
Where for example `css_online` and `css_offline` callbacks are called after a cgroup successfully will complete all allocations and a cgroup will be before releasing respectively. The `early_init` flags marks subsystems which may/should be initialized early. The `id` and `name` fields represents unique identifier in the array of registered subsystems for a cgroup and `name` of a subsystem respectively. The last - `root` fields represents pointer to the root of of a cgroup hierarchy.
Of course the `cgroup_subsys` structure bigger and has other fields, but it is enough for now. Now as we got to know important structures related to `cgroups` mechanism, let's return to the `cgroup_init_early` function. Main purpose of this function is to do early initialization of some subsystems. As you already may guess, these `early` subsystems should have `cgroup_subsys->early_init = 1`. Let's look what subsystems may be initialized early.
@ -292,7 +292,7 @@ Here we may see call of the `init_cgroup_root` function which will execute initi
struct cgroup_root cgrp_dfl_root;
```
Its `cgrp` field represented by the `cgroup` structure which represents a `cgroup` as you already may guess and defined in the [include/linux/cgroup-defs.h](https://github.com/torvalds/linux/blob/16f73eb02d7e1765ccab3d2018e0bd98eb93d973/include/linux/cgroup-defs.h) header file. We already know that a process which is represented by the `task_struct` in the Linux kernel. The `task_struct` does not contain direct link to a `cgroup` where this task is attached. But it may be reached via `ccs_set` field of the `task_struct`. This `ccs_set` structure holds pointer to the array of subsystem states:
Its `cgrp` field represented by the `cgroup` structure which represents a `cgroup` as you already may guess and defined in the [include/linux/cgroup-defs.h](https://github.com/torvalds/linux/blob/16f73eb02d7e1765ccab3d2018e0bd98eb93d973/include/linux/cgroup-defs.h) header file. We already know that a process which is represented by the `task_struct` in the Linux kernel. The `task_struct` does not contain direct link to a `cgroup` where this task is attached. But it may be reached via `css_set` field of the `task_struct`. This `css_set` structure holds pointer to the array of subsystem states:
```C
struct css_set {
@ -358,7 +358,7 @@ So, the overall picture of `cgroups` related data structure is following:
So, the `init_cgroup_root` fills the `cgrp_dfl_root` with the default values. The next thing is assigning initial `ccs_set` to the `init_task` which represents first process in the system:
So, the `init_cgroup_root` fills the `cgrp_dfl_root` with the default values. The next thing is assigning initial `css_set` to the `init_task` which represents first process in the system:
```C
RCU_INIT_POINTER(init_task.cgroups, &init_css_set);