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Commit f6e07d38 authored by Jörg Sommer's avatar Jörg Sommer Committed by Linus Torvalds
Browse files

Documentation: update cgroupfs mount point 



According to commit 676db4af ("cgroupfs: create /sys/fs/cgroup to
mount cgroupfs on") the canonical mountpoint for the cgroup filesystem
is /sys/fs/cgroup.  Hence, this should be used in the documentation.

Signed-off-by: default avatarJörg Sommer <joerg@alea.gnuu.de>
Acked-by: default avatarPaul Menage <menage@google.com>
Signed-off-by: default avatarRandy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 06a2c45d

Documentation/accounting/cgroupstats.txt

+2 −2
Original line number Original line Diff line number Diff line
@@ -21,7 +21,7 @@ information will not be available. 
To extract cgroup statistics a utility very similar to getdelays.c

To extract cgroup statistics a utility very similar to getdelays.c

has been developed, the sample output of the utility is shown below

has been developed, the sample output of the utility is shown below





~/balbir/cgroupstats # ./getdelays  -C "/cgroup/a"

~/balbir/cgroupstats # ./getdelays  -C "/sys/fs/cgroup/a"

sleeping 1, blocked 0, running 1, stopped 0, uninterruptible 0

sleeping 1, blocked 0, running 1, stopped 0, uninterruptible 0

~/balbir/cgroupstats # ./getdelays  -C "/cgroup"

~/balbir/cgroupstats # ./getdelays  -C "/sys/fs/cgroup"

sleeping 155, blocked 0, running 1, stopped 0, uninterruptible 2
 
sleeping 155, blocked 0, running 1, stopped 0, uninterruptible 2

Documentation/cgroups/blkio-controller.txt

+16 −13
Original line number Original line Diff line number Diff line
@@ -28,16 +28,19 @@ cgroups. Here is what you can do. 
- Enable group scheduling in CFQ

- Enable group scheduling in CFQ

	CONFIG_CFQ_GROUP_IOSCHED=y

	CONFIG_CFQ_GROUP_IOSCHED=y





- Compile and boot into kernel and mount IO controller (blkio).

- Compile and boot into kernel and mount IO controller (blkio); see

  cgroups.txt, Why are cgroups needed?.





	mount -t cgroup -o blkio none /cgroup

	mount -t tmpfs cgroup_root /sys/fs/cgroup

	mkdir /sys/fs/cgroup/blkio

	mount -t cgroup -o blkio none /sys/fs/cgroup/blkio





- Create two cgroups

- Create two cgroups

	mkdir -p /cgroup/test1/ /cgroup/test2

	mkdir -p /sys/fs/cgroup/blkio/test1/ /sys/fs/cgroup/blkio/test2





- Set weights of group test1 and test2

- Set weights of group test1 and test2

	echo 1000 > /cgroup/test1/blkio.weight

	echo 1000 > /sys/fs/cgroup/blkio/test1/blkio.weight

	echo 500 > /cgroup/test2/blkio.weight

	echo 500 > /sys/fs/cgroup/blkio/test2/blkio.weight





- Create two same size files (say 512MB each) on same disk (file1, file2) and

- Create two same size files (say 512MB each) on same disk (file1, file2) and

  launch two dd threads in different cgroup to read those files.

  launch two dd threads in different cgroup to read those files.
@@ -46,12 +49,12 @@ cgroups. Here is what you can do. 
	echo 3 > /proc/sys/vm/drop_caches

	echo 3 > /proc/sys/vm/drop_caches





	dd if=/mnt/sdb/zerofile1 of=/dev/null &

	dd if=/mnt/sdb/zerofile1 of=/dev/null &

	echo $! > /cgroup/test1/tasks

	echo $! > /sys/fs/cgroup/blkio/test1/tasks

	cat /cgroup/test1/tasks

	cat /sys/fs/cgroup/blkio/test1/tasks





	dd if=/mnt/sdb/zerofile2 of=/dev/null &

	dd if=/mnt/sdb/zerofile2 of=/dev/null &

	echo $! > /cgroup/test2/tasks

	echo $! > /sys/fs/cgroup/blkio/test2/tasks

	cat /cgroup/test2/tasks

	cat /sys/fs/cgroup/blkio/test2/tasks





- At macro level, first dd should finish first. To get more precise data, keep

- At macro level, first dd should finish first. To get more precise data, keep

  on looking at (with the help of script), at blkio.disk_time and

  on looking at (with the help of script), at blkio.disk_time and
@@ -68,13 +71,13 @@ Throttling/Upper Limit policy 
- Enable throttling in block layer

- Enable throttling in block layer

	CONFIG_BLK_DEV_THROTTLING=y

	CONFIG_BLK_DEV_THROTTLING=y





- Mount blkio controller

- Mount blkio controller (see cgroups.txt, Why are cgroups needed?)

        mount -t cgroup -o blkio none /cgroup/blkio

        mount -t cgroup -o blkio none /sys/fs/cgroup/blkio





- Specify a bandwidth rate on particular device for root group. The format

- Specify a bandwidth rate on particular device for root group. The format

  for policy is "<major>:<minor>  <byes_per_second>".

  for policy is "<major>:<minor>  <byes_per_second>".





        echo "8:16  1048576" > /cgroup/blkio/blkio.read_bps_device

        echo "8:16  1048576" > /sys/fs/cgroup/blkio/blkio.read_bps_device





  Above will put a limit of 1MB/second on reads happening for root group

  Above will put a limit of 1MB/second on reads happening for root group

  on device having major/minor number 8:16.

  on device having major/minor number 8:16.
@@ -149,7 +152,7 @@ Proportional weight policy files 




	  Following is the format.

	  Following is the format.





	  #echo dev_maj:dev_minor weight > /path/to/cgroup/blkio.weight_device

	  # echo dev_maj:dev_minor weight > blkio.weight_device

	  Configure weight=300 on /dev/sdb (8:16) in this cgroup

	  Configure weight=300 on /dev/sdb (8:16) in this cgroup

	  # echo 8:16 300 > blkio.weight_device

	  # echo 8:16 300 > blkio.weight_device

	  # cat blkio.weight_device

	  # cat blkio.weight_device

Documentation/cgroups/cgroups.txt

+35 −23
Original line number Original line Diff line number Diff line
@@ -138,7 +138,7 @@ With the ability to classify tasks differently for different resources 
the admin can easily set up a script which receives exec notifications

the admin can easily set up a script which receives exec notifications

and depending on who is launching the browser he can

and depending on who is launching the browser he can





       # echo browser_pid > /mnt/<restype>/<userclass>/tasks

    # echo browser_pid > /sys/fs/cgroup/<restype>/<userclass>/tasks





With only a single hierarchy, he now would potentially have to create

With only a single hierarchy, he now would potentially have to create

a separate cgroup for every browser launched and associate it with

a separate cgroup for every browser launched and associate it with
@@ -153,9 +153,9 @@ apps enhanced CPU power, 
With ability to write pids directly to resource classes, it's just a

With ability to write pids directly to resource classes, it's just a

matter of :

matter of :





       # echo pid > /mnt/network/<new_class>/tasks

       # echo pid > /sys/fs/cgroup/network/<new_class>/tasks

       (after some time)

       (after some time)

       # echo pid > /mnt/network/<orig_class>/tasks

       # echo pid > /sys/fs/cgroup/network/<orig_class>/tasks





Without this ability, he would have to split the cgroup into

Without this ability, he would have to split the cgroup into

multiple separate ones and then associate the new cgroups with the

multiple separate ones and then associate the new cgroups with the
@@ -310,21 +310,24 @@ subsystem, this is the case for the cpuset. 
To start a new job that is to be contained within a cgroup, using

To start a new job that is to be contained within a cgroup, using

the "cpuset" cgroup subsystem, the steps are something like:

the "cpuset" cgroup subsystem, the steps are something like:





 1) mkdir /dev/cgroup

 1) mount -t tmpfs cgroup_root /sys/fs/cgroup

 2) mount -t cgroup -ocpuset cpuset /dev/cgroup

 2) mkdir /sys/fs/cgroup/cpuset

 3) Create the new cgroup by doing mkdir's and write's (or echo's) in

 3) mount -t cgroup -ocpuset cpuset /sys/fs/cgroup/cpuset

    the /dev/cgroup virtual file system.

 4) Create the new cgroup by doing mkdir's and write's (or echo's) in

 4) Start a task that will be the "founding father" of the new job.

    the /sys/fs/cgroup virtual file system.

 5) Attach that task to the new cgroup by writing its pid to the

 5) Start a task that will be the "founding father" of the new job.

    /dev/cgroup tasks file for that cgroup.

 6) Attach that task to the new cgroup by writing its pid to the

 6) fork, exec or clone the job tasks from this founding father task.

    /sys/fs/cgroup/cpuset/tasks file for that cgroup.

 7) fork, exec or clone the job tasks from this founding father task.





For example, the following sequence of commands will setup a cgroup

For example, the following sequence of commands will setup a cgroup

named "Charlie", containing just CPUs 2 and 3, and Memory Node 1,

named "Charlie", containing just CPUs 2 and 3, and Memory Node 1,

and then start a subshell 'sh' in that cgroup:

and then start a subshell 'sh' in that cgroup:





  mount -t cgroup cpuset -ocpuset /dev/cgroup

  mount -t tmpfs cgroup_root /sys/fs/cgroup

  cd /dev/cgroup

  mkdir /sys/fs/cgroup/cpuset

  mount -t cgroup cpuset -ocpuset /sys/fs/cgroup/cpuset

  cd /sys/fs/cgroup/cpuset

  mkdir Charlie

  mkdir Charlie

  cd Charlie

  cd Charlie

  /bin/echo 2-3 > cpuset.cpus

  /bin/echo 2-3 > cpuset.cpus
@@ -345,7 +348,7 @@ Creating, modifying, using the cgroups can be done through the cgroup 
virtual filesystem.

virtual filesystem.





To mount a cgroup hierarchy with all available subsystems, type:

To mount a cgroup hierarchy with all available subsystems, type:

# mount -t cgroup xxx /dev/cgroup

# mount -t cgroup xxx /sys/fs/cgroup





The "xxx" is not interpreted by the cgroup code, but will appear in

The "xxx" is not interpreted by the cgroup code, but will appear in

/proc/mounts so may be any useful identifying string that you like.

/proc/mounts so may be any useful identifying string that you like.
@@ -354,23 +357,32 @@ Note: Some subsystems do not work without some user input first. For instance, 
if cpusets are enabled the user will have to populate the cpus and mems files

if cpusets are enabled the user will have to populate the cpus and mems files

for each new cgroup created before that group can be used.

for each new cgroup created before that group can be used.





As explained in section `1.2 Why are cgroups needed?' you should create

different hierarchies of cgroups for each single resource or group of

resources you want to control. Therefore, you should mount a tmpfs on

/sys/fs/cgroup and create directories for each cgroup resource or resource

group.



# mount -t tmpfs cgroup_root /sys/fs/cgroup

# mkdir /sys/fs/cgroup/rg1



To mount a cgroup hierarchy with just the cpuset and memory

To mount a cgroup hierarchy with just the cpuset and memory

subsystems, type:

subsystems, type:

# mount -t cgroup -o cpuset,memory hier1 /dev/cgroup

# mount -t cgroup -o cpuset,memory hier1 /sys/fs/cgroup/rg1





To change the set of subsystems bound to a mounted hierarchy, just

To change the set of subsystems bound to a mounted hierarchy, just

remount with different options:

remount with different options:

# mount -o remount,cpuset,blkio hier1 /dev/cgroup

# mount -o remount,cpuset,blkio hier1 /sys/fs/cgroup/rg1





Now memory is removed from the hierarchy and blkio is added.

Now memory is removed from the hierarchy and blkio is added.





Note this will add blkio to the hierarchy but won't remove memory or

Note this will add blkio to the hierarchy but won't remove memory or

cpuset, because the new options are appended to the old ones:

cpuset, because the new options are appended to the old ones:

# mount -o remount,blkio /dev/cgroup

# mount -o remount,blkio /sys/fs/cgroup/rg1





To Specify a hierarchy's release_agent:

To Specify a hierarchy's release_agent:

# mount -t cgroup -o cpuset,release_agent="/sbin/cpuset_release_agent" \

# mount -t cgroup -o cpuset,release_agent="/sbin/cpuset_release_agent" \

  xxx /dev/cgroup

  xxx /sys/fs/cgroup/rg1





Note that specifying 'release_agent' more than once will return failure.

Note that specifying 'release_agent' more than once will return failure.
@@ -379,17 +391,17 @@ when the hierarchy consists of a single (root) cgroup. Supporting 
the ability to arbitrarily bind/unbind subsystems from an existing

the ability to arbitrarily bind/unbind subsystems from an existing

cgroup hierarchy is intended to be implemented in the future.

cgroup hierarchy is intended to be implemented in the future.





Then under /dev/cgroup you can find a tree that corresponds to the

Then under /sys/fs/cgroup/rg1 you can find a tree that corresponds to the

tree of the cgroups in the system. For instance, /dev/cgroup

tree of the cgroups in the system. For instance, /sys/fs/cgroup/rg1

is the cgroup that holds the whole system.

is the cgroup that holds the whole system.





If you want to change the value of release_agent:

If you want to change the value of release_agent:

# echo "/sbin/new_release_agent" > /dev/cgroup/release_agent

# echo "/sbin/new_release_agent" > /sys/fs/cgroup/rg1/release_agent





It can also be changed via remount.

It can also be changed via remount.





If you want to create a new cgroup under /dev/cgroup:

If you want to create a new cgroup under /sys/fs/cgroup/rg1:

# cd /dev/cgroup

# cd /sys/fs/cgroup/rg1

# mkdir my_cgroup

# mkdir my_cgroup





Now you want to do something with this cgroup.

Now you want to do something with this cgroup.

Documentation/cgroups/cpuacct.txt

+10 −11
Original line number Original line Diff line number Diff line
@@ -10,26 +10,25 @@ directly present in its group. 




Accounting groups can be created by first mounting the cgroup filesystem.

Accounting groups can be created by first mounting the cgroup filesystem.





# mkdir /cgroups

# mount -t cgroup -ocpuacct none /sys/fs/cgroup

# mount -t cgroup -ocpuacct none /cgroups





With the above step, the initial or the parent accounting group becomes

With the above step, the initial or the parent accounting group

visible at /sys/fs/cgroup. At bootup, this group includes all the tasks in

becomes visible at /cgroups. At bootup, this group includes all the

the system. /sys/fs/cgroup/tasks lists the tasks in this cgroup.

tasks in the system. /cgroups/tasks lists the tasks in this cgroup.

/sys/fs/cgroup/cpuacct.usage gives the CPU time (in nanoseconds) obtained

/cgroups/cpuacct.usage gives the CPU time (in nanoseconds) obtained by

by this group which is essentially the CPU time obtained by all the tasks

this group which is essentially the CPU time obtained by all the tasks

in the system.

in the system.





New accounting groups can be created under the parent group /cgroups.

New accounting groups can be created under the parent group /sys/fs/cgroup.





# cd /cgroups

# cd /sys/fs/cgroup

# mkdir g1

# mkdir g1

# echo $$ > g1

# echo $$ > g1





The above steps create a new group g1 and move the current shell

The above steps create a new group g1 and move the current shell

process (bash) into it. CPU time consumed by this bash and its children

process (bash) into it. CPU time consumed by this bash and its children

can be obtained from g1/cpuacct.usage and the same is accumulated in

can be obtained from g1/cpuacct.usage and the same is accumulated in

/cgroups/cpuacct.usage also.

/sys/fs/cgroup/cpuacct.usage also.





cpuacct.stat file lists a few statistics which further divide the

cpuacct.stat file lists a few statistics which further divide the

CPU time obtained by the cgroup into user and system times. Currently

CPU time obtained by the cgroup into user and system times. Currently

Documentation/cgroups/cpusets.txt

+14 −14
Original line number Original line Diff line number Diff line
@@ -661,21 +661,21 @@ than stress the kernel. 




To start a new job that is to be contained within a cpuset, the steps are:

To start a new job that is to be contained within a cpuset, the steps are:





 1) mkdir /dev/cpuset

 1) mkdir /sys/fs/cgroup/cpuset

 2) mount -t cgroup -ocpuset cpuset /dev/cpuset

 2) mount -t cgroup -ocpuset cpuset /sys/fs/cgroup/cpuset

 3) Create the new cpuset by doing mkdir's and write's (or echo's) in

 3) Create the new cpuset by doing mkdir's and write's (or echo's) in

    the /dev/cpuset virtual file system.

    the /sys/fs/cgroup/cpuset virtual file system.

 4) Start a task that will be the "founding father" of the new job.

 4) Start a task that will be the "founding father" of the new job.

 5) Attach that task to the new cpuset by writing its pid to the

 5) Attach that task to the new cpuset by writing its pid to the

    /dev/cpuset tasks file for that cpuset.

    /sys/fs/cgroup/cpuset tasks file for that cpuset.

 6) fork, exec or clone the job tasks from this founding father task.

 6) fork, exec or clone the job tasks from this founding father task.





For example, the following sequence of commands will setup a cpuset

For example, the following sequence of commands will setup a cpuset

named "Charlie", containing just CPUs 2 and 3, and Memory Node 1,

named "Charlie", containing just CPUs 2 and 3, and Memory Node 1,

and then start a subshell 'sh' in that cpuset:

and then start a subshell 'sh' in that cpuset:





  mount -t cgroup -ocpuset cpuset /dev/cpuset

  mount -t cgroup -ocpuset cpuset /sys/fs/cgroup/cpuset

  cd /dev/cpuset

  cd /sys/fs/cgroup/cpuset

  mkdir Charlie

  mkdir Charlie

  cd Charlie

  cd Charlie

  /bin/echo 2-3 > cpuset.cpus

  /bin/echo 2-3 > cpuset.cpus
@@ -710,14 +710,14 @@ Creating, modifying, using the cpusets can be done through the cpuset 
virtual filesystem.

virtual filesystem.





To mount it, type:

To mount it, type:

# mount -t cgroup -o cpuset cpuset /dev/cpuset

# mount -t cgroup -o cpuset cpuset /sys/fs/cgroup/cpuset





Then under /dev/cpuset you can find a tree that corresponds to the

Then under /sys/fs/cgroup/cpuset you can find a tree that corresponds to the

tree of the cpusets in the system. For instance, /dev/cpuset

tree of the cpusets in the system. For instance, /sys/fs/cgroup/cpuset

is the cpuset that holds the whole system.

is the cpuset that holds the whole system.





If you want to create a new cpuset under /dev/cpuset:

If you want to create a new cpuset under /sys/fs/cgroup/cpuset:

# cd /dev/cpuset

# cd /sys/fs/cgroup/cpuset

# mkdir my_cpuset

# mkdir my_cpuset





Now you want to do something with this cpuset.

Now you want to do something with this cpuset.
@@ -765,12 +765,12 @@ wrapper around the cgroup filesystem. 




The command

The command





mount -t cpuset X /dev/cpuset

mount -t cpuset X /sys/fs/cgroup/cpuset





is equivalent to

is equivalent to





mount -t cgroup -ocpuset,noprefix X /dev/cpuset

mount -t cgroup -ocpuset,noprefix X /sys/fs/cgroup/cpuset

echo "/sbin/cpuset_release_agent" > /dev/cpuset/release_agent

echo "/sbin/cpuset_release_agent" > /sys/fs/cgroup/cpuset/release_agent





2.2 Adding/removing cpus

2.2 Adding/removing cpus

------------------------

------------------------