https://github.com/torvalds/linux
Revision 85746e429f8e5dc8c5c0beadc0f099cb1feab93e authored by Linus Torvalds on 07 July 2011, 20:16:21 UTC, committed by Linus Torvalds on 07 July 2011, 20:16:21 UTC
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6: (31 commits)
  sctp: fix missing send up SCTP_SENDER_DRY_EVENT when subscribe it
  net: refine {udp|tcp|sctp}_mem limits
  vmxnet3: round down # of queues to power of two
  net: sh_eth: fix the parameter for the ETHER of SH7757
  net: sh_eth: fix cannot work half-duplex mode
  net: vlan: enable soft features regardless of underlying device
  vmxnet3: fix starving rx ring whenoc_skb kb fails
  bridge: Always flood broadcast packets
  greth: greth_set_mac_add would corrupt the MAC address.
  net: bind() fix error return on wrong address family
  natsemi: silence dma-debug warnings
  net: 8139too: Initial necessary vlan_features to support vlan
  Fix call trace when interrupts are disabled while sleeping function kzalloc is called
  qlge:Version change to v1.00.00.29
  qlge: Fix printk priority so chip fatal errors are always reported.
  qlge:Fix crash caused by mailbox execution on wedged chip.
  xfrm4: Don't call icmp_send on local error
  ipv4: Don't use ufo handling on later transformed packets
  xfrm: Remove family arg from xfrm_bundle_ok
  ipv6: Don't put artificial limit on routing table size.
  ...
2 parent s 4dd1b49 + 9491230
Raw File
Tip revision: 85746e429f8e5dc8c5c0beadc0f099cb1feab93e authored by Linus Torvalds on 07 July 2011, 20:16:21 UTC
Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6
Tip revision: 85746e4
cpuacct.txt
CPU Accounting Controller
-------------------------

The CPU accounting controller is used to group tasks using cgroups and
account the CPU usage of these groups of tasks.

The CPU accounting controller supports multi-hierarchy groups. An accounting
group accumulates the CPU usage of all of its child groups and the tasks
directly present in its group.

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

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

With the above step, the initial or the parent accounting group becomes
visible at /sys/fs/cgroup. At bootup, this group includes all the tasks in
the system. /sys/fs/cgroup/tasks lists the tasks in this cgroup.
/sys/fs/cgroup/cpuacct.usage gives the CPU time (in nanoseconds) obtained
by this group which is essentially the CPU time obtained by all the tasks
in the system.

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

# cd /sys/fs/cgroup
# mkdir g1
# echo $$ > g1

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
can be obtained from g1/cpuacct.usage and the same is accumulated in
/sys/fs/cgroup/cpuacct.usage also.

cpuacct.stat file lists a few statistics which further divide the
CPU time obtained by the cgroup into user and system times. Currently
the following statistics are supported:

user: Time spent by tasks of the cgroup in user mode.
system: Time spent by tasks of the cgroup in kernel mode.

user and system are in USER_HZ unit.

cpuacct controller uses percpu_counter interface to collect user and
system times. This has two side effects:

- It is theoretically possible to see wrong values for user and system times.
  This is because percpu_counter_read() on 32bit systems isn't safe
  against concurrent writes.
- It is possible to see slightly outdated values for user and system times
  due to the batch processing nature of percpu_counter.
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