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author | David S. Miller <davem@davemloft.net> | 2013-08-27 22:11:18 -0400 |
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committer | David S. Miller <davem@davemloft.net> | 2013-08-27 22:11:18 -0400 |
commit | 5b2941b18dc5f60a5c14a5c15693f9c58b0dd922 (patch) | |
tree | 30351cd35586f3acf9907aa0f3b4ab9d4f7be81f /Documentation/networking | |
parent | b6750b4056720629e4c1e2e0d05f63692bffad27 (diff) | |
parent | 5828cd9a68873df1340b420371c02c47647878fb (diff) | |
download | linux-5b2941b18dc5f60a5c14a5c15693f9c58b0dd922.tar.bz2 |
Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/jesse/openvswitch
Jesse Gross says:
====================
A number of significant new features and optimizations for net-next/3.12.
Highlights are:
* "Megaflows", an optimization that allows userspace to specify which
flow fields were used to compute the results of the flow lookup.
This allows for a major reduction in flow setups (the major
performance bottleneck in Open vSwitch) without reducing flexibility.
* Converting netlink dump operations to use RCU, allowing for
additional parallelism in userspace.
* Matching and modifying SCTP protocol fields.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'Documentation/networking')
-rw-r--r-- | Documentation/networking/openvswitch.txt | 40 |
1 files changed, 40 insertions, 0 deletions
diff --git a/Documentation/networking/openvswitch.txt b/Documentation/networking/openvswitch.txt index 8fa2dd1e792e..37c20ee2455e 100644 --- a/Documentation/networking/openvswitch.txt +++ b/Documentation/networking/openvswitch.txt @@ -91,6 +91,46 @@ Often we ellipsize arguments not important to the discussion, e.g.: in_port(1), eth(...), eth_type(0x0800), ipv4(...), tcp(...) +Wildcarded flow key format +-------------------------- + +A wildcarded flow is described with two sequences of Netlink attributes +passed over the Netlink socket. A flow key, exactly as described above, and an +optional corresponding flow mask. + +A wildcarded flow can represent a group of exact match flows. Each '1' bit +in the mask specifies a exact match with the corresponding bit in the flow key. +A '0' bit specifies a don't care bit, which will match either a '1' or '0' bit +of a incoming packet. Using wildcarded flow can improve the flow set up rate +by reduce the number of new flows need to be processed by the user space program. + +Support for the mask Netlink attribute is optional for both the kernel and user +space program. The kernel can ignore the mask attribute, installing an exact +match flow, or reduce the number of don't care bits in the kernel to less than +what was specified by the user space program. In this case, variations in bits +that the kernel does not implement will simply result in additional flow setups. +The kernel module will also work with user space programs that neither support +nor supply flow mask attributes. + +Since the kernel may ignore or modify wildcard bits, it can be difficult for +the userspace program to know exactly what matches are installed. There are +two possible approaches: reactively install flows as they miss the kernel +flow table (and therefore not attempt to determine wildcard changes at all) +or use the kernel's response messages to determine the installed wildcards. + +When interacting with userspace, the kernel should maintain the match portion +of the key exactly as originally installed. This will provides a handle to +identify the flow for all future operations. However, when reporting the +mask of an installed flow, the mask should include any restrictions imposed +by the kernel. + +The behavior when using overlapping wildcarded flows is undefined. It is the +responsibility of the user space program to ensure that any incoming packet +can match at most one flow, wildcarded or not. The current implementation +performs best-effort detection of overlapping wildcarded flows and may reject +some but not all of them. However, this behavior may change in future versions. + + Basic rule for evolving flow keys --------------------------------- |