diff options
author | Neil Horman <nhorman@tuxdriver.com> | 2011-11-22 05:10:52 +0000 |
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committer | David S. Miller <davem@davemloft.net> | 2011-11-22 15:22:23 -0500 |
commit | 3ee32fee65ef6a4a8a4188e913be7dd90ba9e058 (patch) | |
tree | 5d450d446498258decc755f65c77c9140102a132 /Documentation | |
parent | 5bc1421e34ecfe0bd4b26dc3232b7d5e25179144 (diff) |
net: add documentation for net_prio cgroups (v4)
Add the requisite documentation to explain to new users how net_prio cgroups work
Signed-off-by:Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: John Fastabend <john.r.fastabend@intel.com>
CC: Robert Love <robert.w.love@intel.com>
CC: "David S. Miller" <davem@davemloft.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'Documentation')
-rw-r--r-- | Documentation/cgroups/net_prio.txt | 53 |
1 files changed, 53 insertions, 0 deletions
diff --git a/Documentation/cgroups/net_prio.txt b/Documentation/cgroups/net_prio.txt new file mode 100644 index 000000000000..01b322635591 --- /dev/null +++ b/Documentation/cgroups/net_prio.txt @@ -0,0 +1,53 @@ +Network priority cgroup +------------------------- + +The Network priority cgroup provides an interface to allow an administrator to +dynamically set the priority of network traffic generated by various +applications + +Nominally, an application would set the priority of its traffic via the +SO_PRIORITY socket option. This however, is not always possible because: + +1) The application may not have been coded to set this value +2) The priority of application traffic is often a site-specific administrative + decision rather than an application defined one. + +This cgroup allows an administrator to assign a process to a group which defines +the priority of egress traffic on a given interface. Network priority groups can +be created by first mounting the cgroup filesystem. + +# mount -t cgroup -onet_prio none /sys/fs/cgroup/net_prio + +With the above step, the initial group acting as the parent accounting group +becomes visible at '/sys/fs/cgroup/net_prio'. This group includes all tasks in +the system. '/sys/fs/cgroup/net_prio/tasks' lists the tasks in this cgroup. + +Each net_prio cgroup contains two files that are subsystem specific + +net_prio.prioidx +This file is read-only, and is simply informative. It contains a unique integer +value that the kernel uses as an internal representation of this cgroup. + +net_prio.ifpriomap +This file contains a map of the priorities assigned to traffic originating from +processes in this group and egressing the system on various interfaces. It +contains a list of tuples in the form <ifname priority>. Contents of this file +can be modified by echoing a string into the file using the same tuple format. +for example: + +echo "eth0 5" > /sys/fs/cgroups/net_prio/iscsi/net_prio.ifpriomap + +This command would force any traffic originating from processes belonging to the +iscsi net_prio cgroup and egressing on interface eth0 to have the priority of +said traffic set to the value 5. The parent accounting group also has a +writeable 'net_prio.ifpriomap' file that can be used to set a system default +priority. + +Priorities are set immediately prior to queueing a frame to the device +queueing discipline (qdisc) so priorities will be assigned prior to the hardware +queue selection being made. + +One usage for the net_prio cgroup is with mqprio qdisc allowing application +traffic to be steered to hardware/driver based traffic classes. These mappings +can then be managed by administrators or other networking protocols such as +DCBX. |