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authorLinus Torvalds <torvalds@linux-foundation.org>2019-07-16 12:21:41 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2019-07-16 12:21:41 -0700
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Merge tag 'docs/v5.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media
Pull rst conversion of docs from Mauro Carvalho Chehab: "As agreed with Jon, I'm sending this big series directly to you, c/c him, as this series required a special care, in order to avoid conflicts with other trees" * tag 'docs/v5.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media: (77 commits) docs: kbuild: fix build with pdf and fix some minor issues docs: block: fix pdf output docs: arm: fix a breakage with pdf output docs: don't use nested tables docs: gpio: add sysfs interface to the admin-guide docs: locking: add it to the main index docs: add some directories to the main documentation index docs: add SPDX tags to new index files docs: add a memory-devices subdir to driver-api docs: phy: place documentation under driver-api docs: serial: move it to the driver-api docs: driver-api: add remaining converted dirs to it docs: driver-api: add xilinx driver API documentation docs: driver-api: add a series of orphaned documents docs: admin-guide: add a series of orphaned documents docs: cgroup-v1: add it to the admin-guide book docs: aoe: add it to the driver-api book docs: add some documentation dirs to the driver-api book docs: driver-model: move it to the driver-api book docs: lp855x-driver.rst: add it to the driver-api book ...
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+==================
+Control Groupstats
+==================
+
+Control Groupstats is inspired by the discussion at
+http://lkml.org/lkml/2007/4/11/187 and implements per cgroup statistics as
+suggested by Andrew Morton in http://lkml.org/lkml/2007/4/11/263.
+
+Per cgroup statistics infrastructure re-uses code from the taskstats
+interface. A new set of cgroup operations are registered with commands
+and attributes specific to cgroups. It should be very easy to
+extend per cgroup statistics, by adding members to the cgroupstats
+structure.
+
+The current model for cgroupstats is a pull, a push model (to post
+statistics on interesting events), should be very easy to add. Currently
+user space requests for statistics by passing the cgroup path.
+Statistics about the state of all the tasks in the cgroup is returned to
+user space.
+
+NOTE: We currently rely on delay accounting for extracting information
+about tasks blocked on I/O. If CONFIG_TASK_DELAY_ACCT is disabled, this
+information will not be available.
+
+To extract cgroup statistics a utility very similar to getdelays.c
+has been developed, the sample output of the utility is shown below::
+
+ ~/balbir/cgroupstats # ./getdelays -C "/sys/fs/cgroup/a"
+ sleeping 1, blocked 0, running 1, stopped 0, uninterruptible 0
+ ~/balbir/cgroupstats # ./getdelays -C "/sys/fs/cgroup"
+ sleeping 155, blocked 0, running 1, stopped 0, uninterruptible 2