Re: [PATCH v2 9/9] Add documentation about kmem_cgroup

From: Randy Dunlap
Date: Thu Sep 08 2011 - 19:13:25 EST


On 09/06/11 21:23, Glauber Costa wrote:
> Signed-off-by: Glauber Costa <glommer@xxxxxxxxxxxxx>
> CC: David S. Miller <davem@xxxxxxxxxxxxx>
> CC: Hiroyouki Kamezawa <kamezawa.hiroyu@xxxxxxxxxxxxxx>
> CC: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>
> CC: Randy Dunlap <rdunlap@xxxxxxxxxxxx>
> ---
> Documentation/cgroups/kmem_cgroups.txt | 27 +++++++++++++++++++++++++++
> 1 files changed, 27 insertions(+), 0 deletions(-)
> create mode 100644 Documentation/cgroups/kmem_cgroups.txt
>
> diff --git a/Documentation/cgroups/kmem_cgroups.txt b/Documentation/cgroups/kmem_cgroups.txt
> new file mode 100644
> index 0000000..930e069
> --- /dev/null
> +++ b/Documentation/cgroups/kmem_cgroups.txt
> @@ -0,0 +1,27 @@
> +Kernel Memory Cgroup
> +====================
> +
> +This document briefly describes the kernel memory cgroup, or "kmem cgroup".
> +Unlike user memory, kernel memory cannot be swapped. This effectively means
> +that rogue processes can start operations that pin kernel objects permanently
> +into memory, exhausting resources of all other processes in the system.
> +
> +kmem_cgroup main goal is to control the amount of memory a group of processes

kmem_cgroup's main goal

> +can pin at any given point in time. Other uses of this infrastructure are
> +expected to come up with time. Right now, the only resource effectively limited

resources

> +are tcp send and receive buffers.

or:
the only resource effectively limited
is TCP network buffers.

> +
> +TCP network buffers
> +===================
> +
> +TCP network buffers, both on the send and receive sides, can be controlled
> +by the kmem cgroup. Once a socket is created, it is attached to the cgroup of
> +the controller process, where it stays until the end of its lifetime.
> +
> +Files
> +=====
> + kmem.tcp_maxmem: control the maximum amount in bytes that can be used by

controls the maximum amount of memory in bytes ...


> + tcp sockets inside the cgroup.
> +
> + kmem.tcp_current_memory: current amount in bytes used by all sockets in

current amount of memory in bytes ...

> + this cgroup


--
~Randy
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