User`s guide

Networking

• Charge the pages dirtied by an exited process to random dirtying tasks. (3.3)

• Allow the poll time and call intervals to balance dirty pages to be controlled by the value of the

max_pause parameter. (3.3)

• Fix dirtied pages accounting on sub-page writes. (3.3)

• Introduce the dirty rate limit to compensate a task's think time when computing the final pause time. (3.3)

• Reduce dirty throttling polls and CPU overhead. (3.3)

• Avoid tiny dirty poll intervals. (3.3)

• Make swap-in read-ahead skip over holes, allowing the system to swap back in at several MB/s, instead

of a few hundred kB/s. (3.4)

• Introduce bit-optimized iterator and radix tree cleanup in the core page cache. (3.4)

• Improve allocation of contiguous memory chunks by adding DMA mapping helper functions. (3.5)

• Remove swap token code and lumpy reclaim. (3.5)

• Improve throughput and reduce CPU overhead by allowing swap read-ahead to be merged. (3.6)

• Add cgroup controller that allows HugeTLB usage per control group to be limited and enforces the limit

during page faults. (3.6)

A.9 Networking

• Add CPU fanout policies for hashing to the packet interface based on mapping socket buffers to Rx

hashes, and a pure round-robin scheme. (3.1)

• Improve the client announcement mechanism in the Better Approach To Mobile Adhoc Networking

(B.A.T.M.A.N.) routing protocol. The change resolves performance and latency issues with the previous

implementation by appending client changes (new client joined or client left) to the OGM. System

overhead is reduced by allowing nodes to modify their global tables by means of updates. The new

ROAMING_ADVERTISEMENT packet type eliminates latency and packet drop issues seen with OGM

broadcasting. (3.1)

• Add support for zero-copy socket buffers. Adds user-space buffer support in the socket buffer shared

information. (3.1)

• Use MD5 to compute protocol sequence numbers and fragment IDs per RFC1948. Update code to take

into account current CPU speeds and to use a full 32-bit sequence number. (3.1)

• Add a multicast group for DCB to provide a clean method for disseminating kernel DCB link attributes to

user space. (3.1)

• Add SELinux context support to the AUDIT target of netfilter. (3.1)

• Add range support for IPv4 to netfilter. (3.1)

• Lower the default init retransmission timeout (RTO) from 3 seconds to 1 second per RFC2988bis. The

RTO falls back to 3 seconds if a SYN or SYN-ACK packet has been retransmitted and the TCP time

stamp option is not on. (3.1)

• Implement support for Auto-ASCONF (see RFC5061) in the Stream Control Transmission Protocol

(SCTP) stack. The change includes features for enabling and configuring settings. (3.1)