This patch adds a document of the SUBCPUSETS.
Signed-off-by: KUROSAWA Takahiro <[email protected]>
--- /dev/null
+++ to-work/Documentation/subcpuset.txt 2005-09-08 11:44:47.994331730 +0900
@@ -0,0 +1,129 @@
+Addition to the cpuset filesystem: "subcpuset"
+
+ "subcpuset" directories are incorporated in order to subdivide system
+ resources (ex. cpu, memory) into finer granularity. We must declare
+ the toplevel directory of subcpuset before creating subcpuset
+ directories. This declaration can be done by writing "1" to the
+ "subcpuset_top" file in that directory.
+
+ Subcpuset directories have different attributes (files) from normal
+ cpuset directories.
+
+
+ File added to the normal cpuset directory:
+
+ - subcpuset_top (file, read/write, boolean value):
+
+ This file controls whether the parent directory should become the toplevel
+ directory of subcpuset or not.
+
+ If the content of this file is "1", then mkdir's in the directory create
+ subcpuset directories. If the content is "0" (default), then mkdir's
+ create normal cpuset directories.
+
+ The contents of cpus, mems, cpu_exclusive, mem_exclusive, and
+ notify_release in the directory can not be modified when the content
+ of the subcpuset_top is "1". The content of subcpuset_top can't be
+ changed if the directory already has subdirectories. Also, "1" can't
+ be written to subcpuset_top if cpus or mems is unset.
+
+ Files in the subcpuset directory:
+
+ - <resource>_guar (file, read/write, integer value):
+
+ Writing to this file sets the guarantee value of the <resource>
+ for the subcpuset specified by the directory that this file resides in.
+ This file is optional and does not exist for some resource controllers.
+
+ - <resource>_lim (file, read/write, integer value):
+
+ Writing to this file sets the limit value of the <resource>
+ for the subcpuset specified by the directory that this file resides in.
+ This file is optional and does not exist for some resource controllers.
+
+ - <resource>_cur (file, readonly, integer value):
+
+ Reading this file gets the current amount of the <resource>
+ assigned to the subcpuset specified by the directory that this file
+ resides in.
+ This file is optional and does not exist for some resource controllers.
+
+ - notify_on_release:
+ - tasks:
+
+ These two files have the same functionality as the normal cpusets.
+
+
+Internal interface for the resource controller provided by subcpusets
+
+ - int subcpuset_register_controller(struct subcpuset_ctlr *ctlr);
+
+ The resource controller must register itself by calling this function.
+ This function must be called before the cpuset filesystem is mounted
+ for the first time since boot.
+
+ The argument ctlr should describe the controller information:
+
+ struct subcpuset_ctlr {
+ char *name;
+ int idx;
+ void *(*create_toplevel)(struct cpuset *cs, cpumask_t cpus,
+ nodemask_t mems);
+ void (*destroy_toplevel)(void *top);
+ void *(*create)(void *top, struct cpuset *cs);
+ void (*destroy)(void *ctldata);
+ int (*set_lim)(void *ctldata, unsigned long val);
+ int (*set_guar)(void *ctldata, unsigned long val);
+ int (*get_cur)(void *ctldata, unsigned long *valp);
+ };
+
+ - name:
+ The name of controller, for example: "cpu", "mem_anon", "mem_cache."
+ This string is used for creating <name>_guar file and <name>_lim
+ under the subcpuset directory.
+
+ - idx:
+ This member is used in the subcpuset core code. Resource controllers
+ must not change this value.
+
+ - create_toplevel:
+ Pointer to the function that creates the toplevel resource data
+ of each subcpuset. The function is called when the content of
+ the subcpuset_top file is set to 1.
+
+ - destroy_toplevel:
+ Pointer to the function that frees the area created by the
+ "create_toplevel" function.
+
+ - create:
+ Pointer to the function that is called when a subcpuset directory
+ is created. The function should return the value that can be
+ used to identify the subcpuset and/or control its resource usage.
+ The caller can get this value by calling
+ subcpuset_get_controller_data():
+
+ void *subcpuset_get_controller_data(struct cpuset *cs,
+ struct subcpuset_ctlr *ctlr);
+
+ The resource controller can get the toplevel resource data of the
+ subcpuset by the following function, specifying the "cs" argument
+ as the argument of the "create" function:
+
+ void *subcpuset_get_toplevel_data(struct cpuset *cs,
+ struct subcpuset_ctlr *ctlr);
+
+ - destroy:
+ Pointer to the function that frees the area created by the "create"
+ function.
+
+ - set_lim:
+ Pointer to the function called when the resource limit is set
+ (i.e. write access to the <resource>_lim).
+
+ - set_guar:
+ Pointer to the function called when the resource guarantee is set
+ (i.e. write access to the <resource>_guar).
+
+ - get_cur:
+ Pointer to the function called when the current amount of the
+ resource is queried (i.e. read access to the <resource>_cur).